Native Gardens in Canberra ö.AJ. Butler This book was published by ANU Press between 1965–1991. This republication is part of the digitisation project being carried out by Scholarly Information Services/Library and ANU Press. This project aims to make past scholarly works published by The Australian National University available to a global audience under its open-access policy. Native Gardens in Canberra
G.A.J. Butler
Australian National University Press, Canberra, ACT, London, UK and Norwalk, Conn. 1979 First published in Australia 1979 Printed in Hong Kong for the Australian National University Press, Canberra
® G.A.J. Butler 1979 This book is copyright. Apart from any fair dealing for the purpose of private study, research, criticism, or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission. Inquiries should be made to the publisher. National Library of Australia Cataloguing-in-Publication entry Butler, G.A.J. Native gardens in Canberra. (Canberra companions) ISBN 0 7081 1079 7 1. Wild flower gardening - Canberra. I. Title. (Series)
635.9676'0994'7[ 1 ]
Library of Congress No. 79-54190 United Kingdom, Europe, Middle East, and Africa: Books Australia, 3 Henrietta St, London WC2E 8LU, England North America: Books Australia, Norwalk, Conn., USA Southeast Asia: Angus & Robertson (S.E. Asia) Ptv Ltd, Singapore Japan: United Publishers Services Ltd, Tokyo Foreword
Canberra, the Garden City, challenges gardeners because of its extremes of climate. Plants that grow in Canberra successfully are likely to be adaptable to many other places in Australia and overseas with similar climates. Many excellent books have been published on Australian plants over the years but much of the information is not entirely applicable to our conditions. Geoff Butler relates his experiences on the cultural require ments in growing Australian plants in the ACT. His knowledge, experience, willingness to help and his encouragement of the aims of the Society for Growing Australian Plants, ‘To preserve Australian native flora by promoting its introduction into home gardens, to improve existing species by breeding and selection and to publish this information’, has been greatly appreciated by the Society. This book is one of a series related to this region and has been designed as an easy reference, a take it into the garden with you, book. It will be of great assistance to all Australian gardeners.
John Pike Federal President, S.G.A.P. Canberra 1979 Acknowledgments
My deepest thanks go to my wife, Jean, for her patience and understanding while this book was being prepared, Also thanks to Marcia Else and Heather Maxwell respectively, for manu script reading and typing, and to Nancy Carriage for some of the line drawings. Without their efforts this book would not have been finished.
iv Contents
Foreword
Acknowledgments
Introduction 1 Myths Surrounding Australian Plants 2 Canberra’s Climate 9 Fertilising 12 Weeds and Weed Control 19 Pruning 25 Watering 36 Mulches and Mulching 39 Propagation 44 Pests 60 Diseases 67 Australian Plants for Pond Use 74 Indoor Plants 79 Suitable Plants 86
v Introduction
When I was first approached to compile this book I was eager to put pen to paper and write of my experiences of gardeningwith Australian plants in a cold climate. On further consideration I thought: What else could be said about Australian plants in cultivation? So much has been written by various authors from many areas of Australia and overseas. However, much of this information is contained in journals and papers that are not freely available to the public and in many instances only touch on one or two aspects of this subject. Also remembering what some authors have written I hoped I might be able to contribute some more modern ideas on cultivation and help to dispel many of the myths that have surrounded, and continue to surround, Australian plants when grown in a garden. The book has been based on my personal experiences with Australian plants grown in a cool climate, of which Canberra and environs is a good example. I expect some of the ideas expressed in the following chapters to cause some consternation amongst more ‘traditional’ native plant gardeners and horticul turists. If it does this I have achieved my aim. To initiate new ideas and perhaps contribute towards more experimentation amongst more experienced gardeners and to provide a guide for new gardeners is the basic reason for which it has been written. The book is, I hope, written in an easy to read style. This is for the benefit of the novice gardener. I have thus tried to keep all terms used non-technical. The book was also undertaken because of the continued rising interest in Australian plants. As people have started to take an increased interest in conservation issues over the last five to ten years, a corresponding interest in Australian plants has occurred. They are now wanting to plant more Australian species in their gardens to attract the local and to an extent migratory fauna in their area. I hope the book will be of some use as a guide as to what to plant for this purpose. I feel that I must stress again that the book is based on my personal experiences and is aimed at cool temperate regions of Australia. Geoff Butler Canberra, 1979
1 Myths Surrounding Australian Plants
This seems to be the obvious point to start a book on Australian plants in cultivation. In the past there have been many myths surrounding this subject. These myths are now fading as our knowledge of Australian plants is increasing and many species are proving their worth in cultivation and their worth of cultivation. The Australian continent is extremely large, the distance from Sydney to Perth being nearly as great as that from London to Moscow. Within this continent are many different environ ments ranging from deserts to rainforests, alps to coastal plains, wet forests to drv forests, marshes and heaths. Many species of Australian plants are found only in certain environments or localities and many have been able to adapt themselves to varying environments. As diverse as these environments and climatic zones are, so are our plants. So it can be seen that many species will be hard to grow in the Canberra environment, that all Australian plants cannot be grouped, as they quite often are, as easy-to-grow, low maintenance plants. What must be remembered is that the more popular exotic species grown in Canberra, as in any other climatic conditions, have in many cases been selected and bred for particular requirements such as hardiness, reliability, showiness, resilience to pests and diseases, and many other factors. This work has been carried out over many centuries and, in some cases, thousands of years. On the other hand Australian plants have not yet been in cultivation for 200 years, and even during this time verv little work has been done on the selection of certain forms or characteristics, nor has planned breeding work for cultivars been carried out to any great extent. We have only just begun to sheathe the axe, put the bulldozer into neutral and start to look at and explore the bountiful supply and potential of our own flora. Some work is being done by such interested groups as the Society for Growing Australian Plants and institutions such as the National Botanic Gardens in Canberra, but as yet the field has hardly been tapped. Perhaps the most provocative way to write this chapter is to quote some of the common myths and then provide a short
2 answer to each. Native plants have to be planted close together to provide mutual support and to hold one another up. This seems to be one of the most common statements made about Australian plants. It may well be the main reason that so many of the older Australian plant gardens in Canberra are of the ‘bush’ type, although I would like to think that they have simply been overplanted because the owners wished to have the greatest variety of species possible in their garden. Some of these gardens have been overplanted to the extent that it has led to an impenetrable mass of vegetation. The initial idea probably stemmed from observations of plants growing in the wild, where they often do grow close together. Plants growing in this situation are usually poorer specimens as they have to compete for light, water and soil nutrients. The same species seen growing in a more open situation or in an open garden is far better than a crowded specimen. Close competition usually leads to a water stressed, etiolated and generally ragged appearance and a plant in this condition probably needs holding up! Australian plant gardens are maintenance free. It appears to me that manv people who believe that they do not have ‘green fingers’ want to plant native gardens because they believe them to be maintenance free. I have regular communication with many highly experienced Australian plant gardeners who jokingly say they are still trying to establish that sort of garden. No garden is maintenance free. With a few simple procedures a garden can be a lower-maintenance prospect but, unfortunately, pests, diseases, weeds and the climate have already heard what you are trying to do and do their best to prevent you. Some control or prevention measures against these factors have to be carried out to keep the garden looking reasonably respectable. Native plants attract insects. A great variety of insects are attracted to Australian plants as they are equally to many exotic species. These include nectar feeders, sap sucking bugs, leaf chew'ers and defoliators and a host of others. Not all insects are harmful to plants and most are certainly not offensive to humans in any way. Exotic species also attract and harbour many insect species and succumb to some form of damage by pestiferous species just as many Australian plants do. Various control measures are readily available to the home gardener if insect pests do become a problem by causing damage to plants or by entering the house This totally unjustified criticism is all too often levelled solely at Australian plants. Native plants are pest free. This is also often heard stated by
3 staunch proponents of Australian plants and it is adequately answered by the previous paragraph. Do not touch or disturb Australian plants once they are growing satisfactorily. 1 sometimes feel that some people think that Australian plants are in a different category from all other forms of plant material. Vegetative material is basically the same no matter which part of the world it may have originated from, and it will respond to certain treatments in much the same manner. Some Australian plants have a tendency to dislike cultivation in their near vicinity due to the disturbance of their feeder root systems, which can be close to the soil surface and thus easily damaged (Some exotic species are in this same category.) The Rutaceae family including Boronia, Correa, Phebalium and Zieria is one example which readily comes to mind. Most Australian plants respond favourably to normal horticultural practices. Native plants are not neatly shaped and Native plants will not tolerate pruning. These statements are closely allied with the previous one. Some Australian plants, if left to grow in a natural way, do become straggly and sparse with age. Others have very attractive natural shapes and forms. The same can be said of exotic species. In my years of experience with Australian plants I have come across only one plant which has shown adverse affects when pruned, Myoporum floribundum. Lateral regrowth just does not appear. All other species I have dealt with respond well to pruning or, in the case of monocotyledons, division of the rootstocks. Most of the more common Australian plants in cultivation benefit enormously from at least one pruning per year. The type of pruning varies from species to species, as explained later. Certain other species will never need to be pruned. Many exotic species are also untidy in appearance or are adversely affected if left unpruned. For example roses must be pruned annually to produce vigorous new flowering wood for the next season and to keep the plants in good shape. Butterfly Bush (Buddleia sp.) tolerates hard pruning at least biennially to produce more flowering wood and to keep it more compact. So pruning improves both Australian plants and exotic species, helping to keep a tidy appearance and produce more flowering wood. Native plants are all spring flowering, Native plants have short flowering seasons, Native plants do not flower at all. This is a series of very rash statements. They can be made only by someone totally lacking in observation or unwilling to see what is available from the huge range of Australian plants suitable for this climate. Many
4 books and articles on Australian plants, from many sources, give details of flowering times, flower colours, length of flowering. A simple reading of this literature nullifies all of the above statements. I would be so bold as to say that in recent years there has been more newly published information accessible to the average gardener on this subject than there has been for exotic species. With such a variety of plants to choose from species can be found with varying flowering times and colours and for flowers in various seasons or over a number of seasons. The flowers of some species may be insignificant but they are usually grown for a different reason, e.g. Zieria cytisoides. It is grown for its delightful shape and grey foliage rather than for its flower display. Native plants fall down in strong winds. Any plant that has been weakened by some external or internal source such as pest or disease, environmental circumstances or even incorrect planting or simply being caught in exceptionally strong winds can suffer this fate. Most instances I have seen can be traced back to poor planting techniques. In the case of existing trees old age or root damage during construction of a dwelling can be a major cause. Bad planting technique usually results in poorly formed root systems usually found after blowing over to resemble very closely the shape of the container from which they were planted. People like to buy big plants for their ‘instant’ garden and the nursery industry caters to this requirement. Most of the large plants are in containers that are far too small. If proper planting techniques are not employed some of these plants will be lost in dry spells or in strong winds. Unfortunately, many native species are sold as ‘advanced’ plants, but nurserymen are only meeting a demand from the public. Planting techniques are dealt with later. Native plants cause hayfever. The poor wattles usually get blamed for this one. Many people suffer from this uncomfortable allergy in Canberra and many will not plant wattles which they believe to be one of the main causes of hayfever. This attitude has probably arisen as many species of wattle are blooming at the time of year when hayfever is a big problem. At this time wattles in full bloom are a very conspicuous part of the landscape. However, wattles generally have a fairly heavy pollen grain which falls quickly to the ground. At this time many other species are flowering, and numerous species of grasses (mostly introduced) that are found in nearby paddocks, reserves and parklands are a major cause of hayfever. Many of these have been medically proven to be the major cause of
5 hayfever in this climate, not the poor, maligned wattles. People who suffer from hayfever will doubtless be affected by various plants of Australian and overseas origin but this is one of those problems that we have to learn to live with. Native plants lack colour. One only has to peruse one of the many volumes available on Australian plants to realise what a wealth of flower and foliage colours we have in our flora. The bush can appear rather drab at certain times of the year, but how can we make such rash statements unless we stop our cars every now and then and get out to look more closely, instead of driving madly down the highway in our haste to reach the next town? Native plants have to be planted with other natives so that they harmonise. There are numerous examples of beautifully designed and planted ‘mixed’ gardens in our city. Many species of Australian plants harmonise extremely well with exotic species. In any garden it is necessary to achieve with your plantings a variety of plant sizes, flower colours and shape, foliage contrasts and flowering seasons. There is an excellent range of Australian and exotic species available in Canberra to meet these criteria, although in recent years this range appears to.be slightly diminishing. Australian plants alone can fulfil these require ments with the many reliable forms, colours, and sizes of plants that are available, but it is certainly not true to say that Australian plants have to be planted with other Australian plants only. Native plants do not like fertilisers. To repeat: Australian plants in cultivation have been chosen from many different environ ments and soil types. Many Australian plants do grow in soils very deficient in some elements normally essential to good growth. These plants have adapted to these conditions by developing very efficient root extraction systems or storage organs in roots. Some are able to survive on minimum nutrition. This does not mean, however, that these plants will not benefit from the application of a fertiliser of some kind as an aid to healthy vigorous growth in cultivation. Some species are more temperamental than others, particularly those with shallow or large surface feeder root systems. To date I have not found one species that has been adversely affected by the more common general purpose fertilisers that are available in Canberra. More to the point, it seems that what we must understand more fully is how much fertiliser we should apply and when we should apply it. Fertilisers also will be treated in more detail later. Native plants do not need watering. This is another commonly
6 heard general statement. Many Australian plants have, once again, evolved over many thousands of years to areas with very low rainfall and low sub-surface moisture. There are also many more species in cultivation from areas with high rainfalls or which grow in constantly wet or moist soils. Even plants from drier areas seem to enjoy small amounts of supplementary water during Canberra’s dry spells. A lack of water can lead to a plant’s appearance becoming very ragged. During dry spells many evergreen species can lose large numbers of older leaves. By providing extra water we can improve the vigour, flowering rates and seasons and nutrient uptake, resulting in plants which are more pleasing to the eye. Watering is discussed later. Native plants have to be grown from seed as they are hard to grow from cuttings. Australian plants are only vegetative material just like vegetative material from any other part of the world. We do not question that in order to preserve certain forms of our more desirable exotics we should grow them from cuttings; some are easy to grow from cuttings while others require a little more knowledge or more sophisticated equipment to grow satisfac torily. This applies to Australian plants also. There are many desirable and reliable forms or clones of Australian plants in cultivation today. The only way to preserve these forms is to grow them from cuttings. This applies particularly to plants known and registered as cultivar forms. To preserve cultivars, vegetative propagation is the only method that can be used, except for some rare instances where certain forms return true from seed. Seed propagation still has its uses in growing plants which can only be raised from seed and in the development of new hybrids or cultivars. It is an unfortunate state of affairs that many commercial outlets are still producing nearly all their Australian plants from seed. This means that due to seedling variation, many poorer forms of plants are reaching suburban gardens; and they do not help to promote Australian plants for cultivation. Native plants from cuttings should all be taken as heel cuttings. Heel cuttings are very useful for propagating some species of Australian plants but normal tip cuttings arejust as efficient for many species. Propagation, too, is dealt with later. Native plants dislike root-promoting hormones used in vegetative propagation. Just as root-promoting hormones have proved beneficial in the propagation of exotic species so thev have for Australian plants. These hormones are available in powder or liquid forms - see ‘Propagation’. And so they go on. I have probably missed many of the other
7 more common fallacies that have become attached to Australian plants. Many of these fallacies are blanket statements on Australian plants which are simply unfair generalisations. Many of them are easy to disprove, some are a little harder. It is up to keen and interested people to grow the many desirable Australian plants suitable for cultivation in their gardens to show people the enormous range and potential our own flora has to offer us.
8 Canberras Climate
What is a Cool Climate? Canberra has a cool, temperate, sub-humid climate. As temperatures are the greatest influencing factor over a plant’s growth, logically we discuss this subject first. Cold is the greatest limiting factor affecting plant growth. Winter months can be particularly severe. During these months heavy frosts afflict the region. It is not unusual to have three or four ' successive frosts in the vicinity o f— 10 to —11°C. These frosts, associated with days of very cold to freezing temperatures and winds, determine what species will grow in the garden. During frosty weather air temperatures can vary considerably, from —8° C to 15° C or thereabouts at the warmest time of the day. This fluctuation is not beneficial for optimum growth of many plant species. Frosts may occur any time from the end of March and have been known to occur to mid-October and early November in the lower areas of Canberra and from mid-May to mid-September in the higher areas around the city. Slightly frost-tender plant species will have a far better chance of survival in the higher areas, where frosts are fewer and less severe. During the summer months the temperatures can be very warm, sometimes reaching 40° C. The region also experiences extended periods of high temperatures varying from 30° C to 36°-39° C, such as the drought season of 1966-7 and more recently the dry summer of 1978-9. Even though high temperatures can limit plant growth, they are not as severely limiting in their effect as frosts. Summer nights are usually cool and even during the summer months occasional cooler spells are experienced. These fluctuations are also not conducive to optimum plant growth. High humidity is relatively rare in Canberra but is sometimes experienced in the warmer months after rain. Humidity can effect the rise of fungal diseases if it persists for too long, though it rarely does in Canberra. Canberra’s rainfall is said to be fairly evenly distributed throughout the year but it seems to me that we get more in the winter months than we do over much of the summer months.
9 The average Canberra rainfall is approximately 625-75mm (25"-27"). Evaporation during summer exceeds the precipita tion rate, but Canberra is fortunate in having more than adequate water supplies, so supplementary watering can be carried out. Snowfalls in Canberra are not unknown. Those that are heavy enough to settle can cause mechanical damage to plants, the increased weight on branches and limbs causing them to snap off. Fortunately, snow is infrequent here and even if it does fall it usually does not settle. Canberra is also subject to infrequent but very heavy hailstorms, which can also result in quite serious mechanical damage to plants. I have seen these sudden but shortlived storms completely strip large shrubs of their new growth and growing tips and cause severe damage to the remaining foliage. New plantings or small plants can also be severely damaged or killed by the pounding of the hailstones. Winds can be one of the worst problems in establishing plants here. During the cooler months we often experience westerly and south-westerly winds which are cold and sometimes quite fierce. They can pummel plants for days on end. As these winds are quite often associated with rain, plants can be loosened in the moist soil causing instability and sometimes death due to damaged root systems. The swirling action of the plant blowing in the wind may also cause extensive abrasive damage to the trunk or stem where it enters the soil. In the warmer months we are subjected to warmer, dry north-west to westerly winds. While these winds are blowing both the transpiration rate of the plants and evaporation of soil moisture are high and they can cause severe drying out of soil and plants and a careful watch on watering should be maintained during this period. One point that is little understood is that frosts are also capable of drying out soils. In winter any period of prolonged frosts should be counteracted by supplementary watering. If plants are water stressed during frosty periods they may succumb more readily to the ravages of frost action. If plants are covered by frost early in the morning it can be hosed off before the sun reaches the plants. This also can lessen the effects of frost burn. The best growing times in Canberra are spring and autumn when temperatures and water regimes are usually at an optimum for plant growth. With some species growth can continue through summer as long as supplementary watering
10 is undertaken. In spite of these adverse factors, Canberra still has quite a reasonable growing climate for a wide range of Australian plant species. This range will probably be extended over a period of time, i( we learn to create and utilise certain microclimatic areas in our gardens which more closely simulate the requirements for satisfactory growth of certain species. Fertilising
Past Usage. In past years most growers of Australian plants have tended to avoid completely the use of fertilisers. If the plant was growing, well or otherwise, then it was thought to be best left alone. If fertiliser was used it was usually blood and bone, but even then it was used very sparingly. It is difficult to understand why this attitude has persisted for so long. The most likely reason is that many Australian soils were known to be deficient in one element or another. As deficiency symptoms were hard to place, and it was a difficult or costly procedure to have soils analysed, then if a plant was growing that was sufficient. Perhaps also the wrong fertilisers were used, or they were applied too liberally with consequent damage to plants from fertiliser burn or the loss of plants from toxic effects. This may have led to the avoidance of fertilisers. Another attitude was that Australian plants were adapted to growing in Australian soils and thus did not need the addition of fertiliser. As explained earlier, Australian plants grow on a wide range of soil types and it is impossible to group all these plants into one category and think that they all require the same soil conditions. Needs can vary from species to species, even those in the same genus. Why Fertilise? Just because a plant occurs naturally in an area deficient in, for example, calcium, it does not follow that the plant will not benefit from an addition of this element to the soil when planted in a garden. This is particularly so when a plant is desired to show its full vigour. In most instances, it is more what type of fertiliser, how much, and when to apply it, that should be considered. The main reason for applying fertiliser is that a plant has to have all its nutritional requirements provided to perform to its full potential. A plant that is not fighting to extract nutrition from the soil is going to be a more healthy, vigorous and, horticulturally speaking, a more- desirable plant. There are a number of elements required for satisfactory
12 growth, and symptoms of deficiency, although sometimes hard to recognise, do show in certain ways. Following is a list of some of the major plant elements, what they are required for, and symptoms that show on plants grown in soil which is deficient in these elements. The elements are not necessarily in order of their importance. 1. Nitrogen. Nitrogen (N) is a major food element. Its main function is in vegetative growth. When nitrogen deficiency is present, a plant is usually stunted and leaves yellow, first I starting at the tips and then gradually spreading to the whole leaf. Leaves are quite often small in size. I 2. Potassium. Potassium (K) is another major food element. The main deficiency symptoms show in leaves developing a bronzy appearance which commences around the edges of the leaf and gradually moves into the centre. This ends in the death of the leaf. The plant generally lacks vigour and is quite often stunted. Potassium is needed for good growth and helps in I disease resistance. This is not a common deficiency in Canberra and most evidence I have seen of it has occurred in plants grown in pots. 3. Phosphorus. Phosphorus (P) with N and K is one of the three major nutrients required by plants. P promotes good root growth and is an aid in flowering and seed formation. A lack of P shows in a reduced growth rate and leaves are usually small and turn a purplish colour underneath. The root system, although not seen, is usually seriously stunted. P is lacking in many of Canberra’s soils, as indeed in many of Australia’s soils. An excess of this element can also have verv deleterious effects on many Australian plants. As most of these plants grow on P- deficient soils it appears that a large number of them have efficient P extraction and storage capabilities. If P is applied too heavily it may be absorbed and toxic effects may result. This element, when applied, must be applied sparingly. Most commercially available NPK general fertilisers appear to be suitable if used at recommended rates. 4. Calcium. Calcium (Ca) is a major food. It is a major component of plant cell walls. Deficiency in Ca usually shows by a slowing down of a plant’s growth. Often the edges of leaves die back and the leaves may fall from the plant. The terminal or apical bud dies and the plant loses its rigidity, with stems or branches becoming weak. Root systems may also be stunted. 5. Sulphur. Sulphur (S) deficiency can be confused with N deficiency. However, it is only the lower leaves that become yellow and stems of the plant become very long and thin. This
13 is not common in Canberra. Sulphur is needed to form good quality proteins within the plant. 6. Magnesium. Magnesium (Mg) deficiency is also not very common here. A lack of Mg shows in the areas of the leaf in between the veins turning yellow and the leaves gradually dying off. The older leaves are the first ones affected. This deficiency is sometimes confused with iron deficiency. Magnesium is present in the chlorophyll or green colouring pigment of the plant and a plant cannot manufacture its food supply properly without it. 7. Trace elements. These are elements essential to vigorous plant growth but deficiencies rarely occur in Canberra soils, particularly clayey soils. The only one I have noted on Australian plants in Canberra is an iron deficiency. This shows in the younger growth turning yellow but the leaves do not die back and are normal in size and shape. The deficiencies above are all that will probably be experienced in Canberra. Fertilisers are available to rectify these deficiencies. Nitrogen deficiency can be remedied by the application of a nitrogenous fertiliser. Calcium ammonium nitrate, more commonly known by its initials CAN, contains 20 per cent Nina slow release form. It is a very safe fertiliser to use in the garden, being released over a period of some 20-odd weeks. Apply CAN at a rate of 40 grams per square metre. Blood and bone is also very useful. When purchasing blood and bone be sure to obtain the powdered form and not the pelleted form. The powder is the natural product which contains 7 per cent N, which is in a slow release form.The pelleted product is manufactured synthetically and has a tendency to burn plants if applied at the same rate as the powder. Blood and bone is a good fertiliser to incorporate in the bottom of the hole at the planting stage. If it is applied as a general dressing to a garden bed it attracts dogs and cats. They like to roll and dig in the garden while they try and trace the origin of the smell. The smell can be quite overpowering and this is probably why the synthetic product was developed. The best method to apply blood and bone to established plants is to dig holes around the plants and pour it in the holes and then seal them off with soil. Sulphate of ammonia is another nitrogenous fertiliser and it contains some 20 per cent N, but it is in a very quick release form. It is more suitable for lawns than for garden beds and it has to be applied in light applications and applied more frequently. It has a tendency to burn foliage and must be well
14 watered in after application. It should be applied at a rate of 20 grams per square metre. The aspect of using Calcium is something new to Australian plants. Up till very recently nearly all literature on Australian plants has stated that calcium (lime) must be kept away from these plants at all costs as they grow naturally in soils lacking in Ca and application of it would seriously affect or destroy them. More recently, however, the association of calcium with many species of Australian plants has been under investigation, prompted by Mr Jim Webb of The Australian National University. The theory is that many species of Australian plants from certain localities require Ca in relatively large quantities for satisfactory growth. Plants grown experimentally in the ground and in pots have shown that the theory has some basis in fact, although there are many other complications involved. The major complication appears to be that if phosphate is supplied in conjunction with calcium it (P) becomes more freely available to the plant and causes necrosis to the plant’s younger tissue and can also lead to death of the plant. It also appears that much of the frost damage that has been caused to plants that seem to require higher levels of calcium could in fact have been caused by the lack of this element. As mentioned in the comments on Ca deficiency a lack of Ca causes leaf dieback and the apical bud often dies. This may appear to be frost damage. As Ca is also a major constituent in cell walls it could be that plants requiring Ca have not had sufficiently well built cells to help them withstand frost and the cell walls have burst in freezing temperatures resulting in true frost damage. Certainly, there are other complicating factors with Ca and Australian plants. These doubtless will come to light with more experimental work. If you are going to grow plants that require Ca it would be better to grow them in a separate garden bed where they could grow in the absence of phosphate. Ca can be supplied to the soil by the application of lime and/or dolomite. Dolomite also provides magnesium to the soil. Incorporation of sea shells, eggshells or limestone rocks or chips also will provide Ca over a longer time period. Potassium, when required, can be applied to the soil by the use of sulphate of potash which contains some 40 per cent K. It is a safe fertiliser to use and should be applied at the rate of 100 grams per square metre. Potassium is not a common deficiency in Canberra. Phosphorus deficiency can be remedied by the application of superphosphate. This must be used sparingly for reasons
15 outlined earlier. If the symptoms of deficiency do appear (this is highly unlikely), superphosphate can be used at the rate of 20 grams per square metre. Superphosphate contains some 9 per cent P which is readily soluble and available to plants. The three main elements that are mentioned above, N, P, K, can also be applied by a more general purpose fertiliser. One of these which is readilv available is Multigro which has N P K available in the ratios of 10 per cent N, 2.8 per cent P and 6.2 per cent K, and this is one that I have used regularly in past years and have noticed no deleterious effects when applied at the rate of approximately 40-60 grams per square metre. Sulphur deficiency will also be remedied by the application of a light dressing of superphosphate. Sulphur deficiency is not common in Australian plants in Canberra. Trace element deficiencies are extremely uncommon in Canberra except for iron deficiency which occasionally affects some members of the Proteaceae Family (Banksia particularly). This can usually be remedied by the application of iron chelates which is very soluble and available instantly to the plant. Apply at the rate of 7 -14 grams per litre and water on and around the plant from a watering can. Trace elements are usually available in sufficient quantities for good growth in clayey soils and as much of Canberra and environs has these types of soils, problems do not usually arise. I have used many of the commercially available fertilisers over the last few years and have had no problems with them. The few instances I have seen of fertiliser damage has been due to the application of too much to the soil, resulting in an overdose for the plants which severely burnt them. In some cases plants were killed. Most fertilisers have a recommended application rate and it is essential that this rate be followed. If you are still unsure or uneasy about using a particular fertiliser, apply it at half strength and watch the plant’s response over a period of a few weeks to a month, and if favourable the application could be increased, if necessary, when it is next applied.
Types of Fertiliser and How to Apply There are many brands and types of fertilisers available to the home gardener. They can be in various forms. Some are powders, some are granulated and some are pelleted. The powdered forms can be very hard to apply by hand methods because they contain excessive dust. They are best spread by means of a hand fertiliser spreader or, as in the case
16 of blood and bone, incorporated into the garden bed, as it is prepared, or by placing a quantity of the powder into holes surrounding the plant and then sealing it over. Granulated fertilisers are much easier to handle. Each granule of the fertiliser, in mixed fertilisers such as 10:4:6 or Multigro, contains the correct ratio of elements as stated on the bag or container. Granulated fertiliser is very easy to spread by hand broadcasting. When applied to the soil and watered in it is usually readily soluble and available very quickly to the plants. Pelleted fertilisers are very common now and are widely used. The pellets are treated with a substance that regulates the amount of nutrient made available to the plant over a period of time. They are practically dust free and are extremely easy to spread by hand broadcasting methods. They can also be incorporated into garden beds as they are established by applying them at the manufacturer’s recommended rate. Calcium ammonium nitrate is a good example of a pelleted fertiliser. In more recent times slow release chemical fertilisers such as Osmocote have been developed. These are available in various rates of time release. One is 3-4 month release and another is 8- 9 month release. Generally the 8-9 month release form is the best one to use in both gardens and pots. The pellets can be dug through the soil or can be applied as a dressing to the surface. Once again, manufacturer’s application rates as stated on the container should be followed. Slow release fertilisers are simply nutrients contained within a semi-permeable membrane and they are released gradually through the membrane. They depend on warmer temperatures and moisture for effective release of the nutrients. They are an excellent general purpose fertiliser for Australian plants. Liquid fertilisers such as Aquasol, Thrive, Zest, and fish emulsion, are examples of the many which are also very beneficial. They come in a moist powder form which is mixed with water or in a liquid form which is further diluted before use. They are safe to use and can be applied with a bucket siphon pump, knapsack sprayer, watering can or other similar devices. When applied to the foliage of plants the nutrients are instantly available. Liquid fertilisers usually contain all the major plant foods plus trace elements and are a good way of providing these elements if they are believed to be in short supply. Liquid fertiliser should be applied to plants in cooler weather, not in strong sunlight, and it is also a good idea to wet
17 plants down with water before applying them. This helps the absorption of the fertiliser and helps to prevent fertiliser burn on more tender species. Results of liquid fertilising are usually noticed within a week of application.
When to Apply Fertiliser Knowing when to apply fertiliser is most important. The best time in our climate is in early spring or late summer-early autumn, just before the plants’ main growing flushes. They are also the main flowering periods for many species. These are the times of the year when the plant will be requiring maximum nutrients for its growth, flowering, fruit set and development. During the summer months most species will usually slow down in growth or even become semi-dormant and will resume growth in early autumn. Care must be taken that growth is not forced on a plant as it enters the winter period. If this is done the plant will face the frosts with large amounts of soft, succulent growth and these lush tips stand a good chance of being severely burnt or killed by the heavy frosts that we experience in Canberra. Slow release fertilisers can be applied at the same time as other fertilisers, as they depend on warm temperatures for nutrient release. As temperatures drop the nutrient release is slowed down if not completely stopped and will start again as temperatures rise in the spring. An application of slow release fertiliser in the spring months will release until the following autumn and will then be depleted and this is probably the best season in which to apply them.
Fertiliser Storage and Safety 1. Store in clearly labelled containers. 2. Store out of the reach of children. 3. Store in a cool, dry place. 4. Do not use fertiliser containers for any other purpose. 5. When using dusty fertilisers do not breathe the dust. A respirator is handy for spreading or handling in this instance. 6. Wear gloves when handling fertilisers. 7. Apply fertiliser at recommended rates. 8. Water fertiliser in after application except in the case of liquid fertilisers. The majority of plant nutrient elements are available to plants at a pH of between 6.5 and 7.5 Most plants are tolerant of this pH and it is a good aim to get the soil to this level and the nutrients will be readily available to them..
18 Weeds and Weed Control
What is a Weed? A weed is a plant that is growing out of place or where it is not wanted. This means that any plant, even shrubs and trees, can be classed as weeds in certain circumstances. However, for the purpose of this book, I will refer only to those plant species more commonly recognised as weeds in Canberra gardens. Weeds are a constantly recurring problem in all gardens. Many though not all of them are species introduced from overseas, i.e. they are plants growing out of their natural environment. Some of these weeds were introduced at the time of earliest colonisation and settlement and others such as Skeleton Weed (Chondrilla juncea) as recently as 1915. Some species which are weeds in gardens play a very important part for grazing in rural areas and were introduced originally as pasture species. Others were introduced as contaminants in seed supplies of more useful species. These germinated, grew and rapidly spread when the seed was sown. Some seeds or plants have doubtless been brought into Australia either unawares or deliberately, by people travelling from overseas, and some of these have become weeds A good example of this is Water Hyacinth (Eichornea crassipes), which was originally introduced from South America as a horticulturally desirable aquatic plant, but when introduced to water courses in warmer climatic regions of Australia it spread to plague proportions and is proving difficult to control. Many Canberra suburbs are built on what were previously rich grazing areas. Even suburbs not built on such areas are reasonably close to them. This factor has accentuated the weed problem in most suburbs. The vast areas of parklands and adjacent grazing areas are a source of recontamination for gardens year after year.
Reasons for Plants becoming Weeds The reasons for certain species of plants becoming weeds are many. First there is their adaptation or naturalisation to a particular climate. Many introduced species have a capacity to spread to a far greater extent than they would in their natural
19 environment. When introduced, the species find the climate very compatible for good growth. They are able to grow and produce viable seed and this spreads, sometimes at alarming rates. Some species are present all year round and are capable of reproduction for long periods during the year and, in some cases, capable of a num ber of life cycles during the growing season. Second is the seed production rate. Many species form seed in vast quantities and can have a very high viability and germination rate. Third, many species have very efficient seed dispersal mechanisms such as explosive seed containers or fruits. Some have burrs which get caught up in an animal’s fur or hair and are thus carried for great distances. Others are of good design for wind or water dispersal. Some seeds are contained in fruits which are an attractive source of food for animals and birds and the seeds can be expelled from the body great distances away. Man, in his many activities, is also a major cause of weed spread. Fourth, many weed species have very vigorous growth rates. Some have as many as two or three reproductive cycles during the period of one growing season. Growth rates can be so vigorous that certain species are able to smother other species of plants very efficiently. Fifth is the absence of pests and/or diseases. When weeds were introduced from other parts of the world they left some or all of their natural predators or diseases in their place of origin. If native predators do not find the plant attractive as a host for their young, or certain diseases are not compatible to them, their spread can be extremely rapid, A good example of this is Prickly Pear (Opuntia inermis) introduced into Australia from the Gulf of Mexico. It became a major weed of vast areas of Australia and it was not until the introduction of one of its natural predators, a moth known as Cactoblastis cactorum, that it was brought under reasonable control. Weed species that have poor seed dispersal mechanisms or that produce lower quantities of viable seed usually make up for this in other ways. One of these takes the form of strong and deep rooting stoloniferous or rhizomatous growth. These stolons or rhizomes grow quickly and can spread for long distances from the parent plant. They can then take root and if separated from the parent plant can exist on their own. This factor will be shown later to be a ready means of propagating more desirable species (see section on division in the chapter on propagation). 20 Weeds are commonly introduced to gardens from nursery containers. When purchasing plants, make sure there are no contaminants in the container. The chief weeds introduced by this means are Oxalis and Cardimine. If the potting mix soil had not been sterilised before use, the weed species that could be I present would number many more. Introduced topsoils can also contain many weeds. Some of ; the topsoils provided in Canberra are taken from alluvial deposits along rivers or from other flood plain areas and the weed content of these soils can be quite staggering. The areas where these soils have been taken are quite rich and have been grazed over many years. Owing to the introduction of pasture grasses and other associated undesirable species, the seed can easily be transported into your garden.
Damage caused by Weeds Weeds provide competition for other plants by vying for available soil moisture, soil nutrient and light. These factors are particularly important where newly planted or smaller growing plants are concerned. Most weed species have extremely vigorous growth rates and it only takes a very short time to completely overgrow young or small growing plants. Weeds, along with other plants, can affect people’s health. Many weeds produce a lot of very fine pollen which is responsible for much of the hayfever in our district; e.g. Lamb’s Tongue (Plantago lanceolata) and Rye Grass (Lolium perenne). Weeds can also harbour certain pests and diseases that are capable of spreading to more desirable plants.
Controlling Weeds There are two main ways of controlling weeds: by physical or chemical means. Physical control is at all times preferable to the use of chemicals. Some chemicals can persist in the environ ment and many can be dangerous if handled by inexperienced persons. However, chemicals do have a part to play in the control of some weed species in certain situations and so will be dealt with in some detail. Control of weeds is necessary at all times of the year. Some species die down during the cooler months but other species persist throughout the year. There is an old saying that ‘one year’s seeds means many years weeds’ and truer words were never spoken. Alw'avs try to control weeds before they reach the flowering and, particularly, the fruiting stage. If seeds are shed before control takes place, you can be assured of a bountiful supply of weeds for following seasons. 21 Physical Control of Weeds This is the removal of weeds by physical means. Hoes and other such items of equipment can be used in certain instances but more usually it entails the monotonous and sometimes laborious task of hand pulling weeds. Some weeds are shallow rooted and are pulled easily, especially when the ground is moist. At any time it is better to weed when the ground is moist, as the weeds can be completely removed from the soil easily. Some species such as Couch Grass (Cynodon dactylon), Sheep Sorrell (Rumex acetosella) and Wood Sorrell (Oxalis corniculata) have vigorous rhizomatous and stoloniferous growth and these growths must be completely removed for effective control. Others have long, strongly rooting tap roots. Good examples are Dandelion (Taraxacum officinale) and Cats ear or Flatweed (Hypochoeris radicata). The tap root must be removed completely or it may reshoot very quickly to form a new plant. Oxalis and Cardimine (Cardimine hirsuta) have ‘explosive’ seed containers and only have to be touched when mature to explode open and scatter seed over long distances. These species must be controlled before they reach this stage. When weeds are removed it is better to dispose of such species as Couch, Sorrell and Oxalis completely, preferably to the garbage tip or by burning. These species can survive even a good composting. Other less resilient weeds can be thoroughly composted, removed or burnt.
Chemical Control of Weeds These chemicals are known as herbicides and some of them are capable of destroying all vegetative growth, whereas others are more specific to certain groups of plants. There are many different types and brands of herbicides available today. Some of these are relatively safe to use while others are dangerous and have a long residual life in the soil. When using herbicides, and for that matter insecticides and fungicides, there is a certain set of rules that must be followed to ensure safe handling of the chemical. These are as follows: 1. Always read the label carefully and make up the spray mixture according to manufacturer’s directions. 2. Only make up enough spray to do the job at hand. Having to dispose of excess is undesirable. 3. Always use gloves when mixing sprays. It is a good idea to use a respirator when mixing powdered concentrates. 4. Do not use one mixing implement or container for both herbicides and pesticides. Some herbicides can be very
22 persistent in spray equipment and may damage or kill plants that are subsequently sprayed for some form of insect control. 5. Do not spray in windy weather as wind can create spray drift. If this drift comes into contact with garden plants damage or death could result. Drift can also blow back onto exposed skin areas. 6. Spray in the cool of the day. Best results are obtained at this time, particularly with the highly mobile translocated sprays, as more time is available for absorption before evaporation takes place. It is also a more comfortable time of the day for the heavily dressed operators. 7. Soap and water should be kept handy for quick washes in case of spillage. It is a good idea to shower thoroughly after spraying. 8. Wear protective clothing that covers as much skin area as possible. It is also a good idea to wear a respirator if spray is to be used for a considerable time. Protective clothing should be washed separately after use. 9. Do not eat or smoke while spraying. 10. Take care at all times to ensure that spray does not contaminate areas unnecessarily and that it does not contaminate desired plants. 11. Empty containers should be holed and then disposed of by burning and burying. Do not leave containers where they may be reused or tampered with. Do not reuse containers for any other purpose. 12. Make sure all containers are clearly labelled with indelible writing and that this label stays with the container. 13. Store full containers in a safe position where children cannot get at them. They are best stored in a vented, locked cupboard in a cool place, not under kitchen or laundry sinks. Herbicides should be applied during periods of lower temperatures (15°—25°C) for best results. Lower temperature than this slows the action of the herbicide and higher temperatures can dry the spray out on the plant thus preventing good absorption and translocation. Best action is obtained when the plant is growing vigorously and when the soil is moist, which means that there will be good water flow in the plant. It is good with most herbicides to have several hours without rain after spraying for best effects to be attained. Herbicides work in a varietv of ways. When applied to foliage some are absorbed and partially translocated and others are translocated to the extremes of a plant’s tissues including the
23 root systems. A herbicide can kill a plant in one of three main ways: 1. When absorbed they form toxins in the plants’ cells which destroy the cells, e.g. Paraquat. 2. They can prevent the formation of new plant tissue, e.g. Dalapon 3. They can cause chloroses by interference with normal ! photosynthetic processes, e.g. Amitrol Herbicides can be : applied to foliage where it is absorbed by the plant or to soils where they kill weed seeds as they germinate or they can affect ] established weeds by being taken up by root systems. There are three main types of herbicides. Pre-emergents are efficient in eliminating weeds from the earliest stages. These herbicides are applied to the soil and kill seedlings as they germinate. Contact herbicides kill plant tissue where they contact. These must be thoroughly distributed on the weed for good results, e.g. Dinaseb, mineral oils. Translocated herbicides move from the area where they are applied to the plant to other parts of the plant, e.g. Glvphosate. At all times the right herbicide must be used to control the right weed. Certain herbicides are more efficient in controlling certain weeds and may not be as effective on other species. When applying the herbicide care should be taken not to overdose as burning may occur which will prevent further translocation. Some herbicides have a surficant contained in them and others have to have a surficant added to them. A surficant is simply an agent that is added to the mixture to enable the chemical being used to adhere more efficiently to the plants being sprayed. Detergent can be used for this purpose.
24 Pruning
Pruning is the removal of plant growth, living or dead, usually by artificial means, to make a plant conform to a desired shape or form. Pruning is basically aimed at controlling the height or shape of a plant and is also an aid in controlling its health. Pruning simply arrests growth, it does not stop it. The genetic makeup of the plant will ensure that it will continue to try to grow to its ultimate proportions. Many growers of Australian plants in the past have been very reluctant to prune plants which were growing satisfactorily, perhaps because plants were pruned too hard and succumbed because of it. Others think that a plant’s natural form is best and do not wish to alter it to any extent. My experience has been that most species grown respond well to pruning. The only requirement is to approach pruning carefully until experience is gained in the art, and the method of pruning to use on individual species is understood.
Reasons for Pruning Pruning is undertaken for a variety of reasons. It can be used to remove dead or dying sections of a plant. If these portions are not pruned out the plant’s appearance is unsightly. Dead growth can also provide access for insect or disease attack and so this is a major reason for pruning. Dead growth may not only mean branches or stems. It may also refer to spent flowers or the formation of unwanted fruiting bodies which can sap the plant of strength and nutrition when vegetative growth may be more beneficial. Pruning can also be used to remove diseased or pest-ridden sections of shrubs or trees where they are accessible to pruning. If the pest or disease is widespread other means of control will have to be used, but if it is not in plague proportions, pruning is an excellent alternative to bring the problem under control. Another reason for pruning, and probably the most important one, is to shape a plant into the form we desire. This is ornamental pruning and is the most common sort of pruning used with Australian plants. It is used to keep plants more compact, to increase lateral vegetative growth and thus
25 improve the density of the plant and to provide more flowering wood for the next season.
When to Prune Pruning can be carried out at most times of the year for many plants, though it can be more convenient to do it at one time of the year. The main thing to remember before pruning is the flowering season of the plant so that the next season’s flowers are not pruned off. Fresh flowers can be cut for the house. They serve two functions: bringing some of the garden into the house to enjoy, and giving a shrub its annual pruning. After the flowering season is also a good time. Then what can be unsightly spent flowerheads can be removed and the formation of unwanted fruit prevented, unless the fruit is a desired attraction of the plant. Tip pruning can be carried out all year. It is conveniently done while walking around the garden. All that is needed is a sharp nip of the fingernails. Pruning can also be carried out while collecting propagation material. In our climate this is usually done from November to March, but some material is available at most times of the year and so pruning can be carried out whenever propagation material is needed. Another excellent time to prune is during the winter months when plants are dormant. At this time of the year sap flow in the plant is at a minimum. Pruning at this time eliminates the possibility of excessive ‘bleeding5 from the pruning cuts.
How to Prune Pruning simply entails the removal of a certain length of the growing tip of a stem or branch but can at times mean the removal of larger sections of a plant. When pruning, the stem must be cut back to a lateral or axillary bud. This is found at the base (or node) of the leaf. The cut must be made at this point as any stem (or internode region) which is left on the plant will die back to the axillary bud. This dieback can continue down the stem and can leave the stem open to insect or disease attack. Make the cut so that it slopes away from the axillary bud. This prevents water being shed onto the bud, which may cause the end to rot.
Types of Pruning Tip pruning is probably the most commonly used and most useful type of pruning with Australian plants in cultivation. It is used mainly to control the production of flowers and
26 subsequent fruiting of the plant. It is carried out by the removal of the apical bud and a length of stem below the bud. The length of stem to be removed will vary with the species being pruned. If the plant produces long, fast-growing shoots, up to a third of the newer growth can be safely removed. With plants that produce shorter growths each season, it may only be necessary to remove the bud and one or two nodes below it. With smaller, closely internoded shrubs a very efficient method of carrying out tip pruning is to use a pair of hedge shears. Simply remove a layer of growth right over the circumference of the plant. This procedure makes the plant look rather rounded and formal for a short time but, as new growth breaks out, it soon diffuses the shape of the shrub. Tip pruning can be satisfactorily carried out at any time of the year.
axillary bud
pruning cut made here
leaf node area
Where to cut when pruning
There is a natural means of tip pruning that occurs each winter with some species of slightly frost-tender plants. Frost kills the tip growths on these species and this action has the same effect as mechanical tip pruning. When spring arrives the axillary buds will shoot and form new lateral growths. Length Pruning or Thinning Out This is the method used to control the height and shape of a plant. It can also be used to make a plant safe, particularly trees, where large, unsound limbs can be removed. This method is used on less temperamental species to aid in reducing the size and confining it to a set area. This method is carried out only on those plants that respond to cutting back into older wood. A few that come to mind immediately are many of the commonly
27 grown species of Leptospermum, Melaleuca, Callistemon, Hakea, and Grevillea. Many of these species can be cut back very hard and the old wood will reshoot and form new branches. This too can be a matter for experimentation. Start gradually by cutting off shorter lengths of branches and watch for response. If new shoots form, the next time pruning takes place you can cut into slightly older wood and watch for response again. At times, when pruning, large wounds are left on plants. These can leave the plant open to attack from either pests or disease, and they must be sealed. The best method to seal the wound is as follows: after removing the spigot from the plant, with a pruning saw or chainsaw, smooth the surface of the cut, which may still be slightly rough o r ‘fuzzy’. Use a sharp knife or chisel to give a smooth surface to the wound. When this has been done the wound can be painted. The best sealants are any one of the many bituminous compounds that are readily available at hardware, nursery or garden centre outlets. The sealant is simply painted onto the wound to cover the whole of the exposed tissue. In only a short time the plant will start to heal itself by building new bark tissue at the edges of the wound which will gradually grow and seal the wound over. With really large wounds the healing can take many years and some species heal more slowly than others. With bad wounds the healing process may persist for the rest of the life of the plant. Good examples of this can be seen on some of the massive River Red Gums (Eucalyptus camaldulensis) along the Murray River. At some stage Aborigines have removed much of their bark for canoes, and they are still healing after many decades. Any cut over 214-3 cm in diameter should be sealed in the above manner.
1 S * /
! X s' 2- / ' !• i 3.
Cuts made to remove a large bough
28 A large wound treated with bituminous sealing compound showing healing tissue around the edges of the wound.
29 A large wound that has practically healed over
30 Tree Surgery. Occasionally trees may need some form of pruning, especially mature or existing trees. This may be in the form of removal of living or dead branches or the removal of damaged or diseased limbs. When removing main branches large cuts have to be made and then the heavy branches have to be lowered to the ground. When doing this, the finished cut must be as hard against the trunk or bough as possible. When large branches are being removed it is essential to undercut the bough being removed. This cut only needs to be through a quarter of the diameter of the branch. The saw is then removed from the cut and the bough is cut j through from the top. The procedure of bottom cutting prevents the bark from being torn off the plant as the unwanted limb falls. When the limb is removed the small spigot of branch that remains is sawn off from the parent. Removal of the spigot makes for a better appearance to the finished job. If large branches have to be removed from trees growing near houses or over established beds, it is highly recommended that experienced tree surgeons or tree loppers are employed as their experience and equipment can make the job safer and probably less costly in the long term. The main tools needed to carry out satisfactory pruning are a pair of good quality secateurs, a budding or pruning knife, wood chisel, hammer or mallet and a pruning saw. These tools should be kept in good condition and should have sharp cutting edges. This makes the job easier for you as well as for the plant being pruned. If moving from plant to plant, it is an excellent idea to clean your tools when moving from one plant before starting work on the next. This helps to minimise or eliminate the chance of spreading any disease, mainly of a bacterial, viral or fungal nature. Tools are easily cleaned by wiping them with a cloth soaked in methylated spirits. The other materials needed for pruning are a tin of bituminous paint or similar sealing substance, a good quality paintbrush and thinners to clean the brush after use. These tools should be sufficient to do any general pruning jobs in a garden situation.
Where to be Careful when Pruning Some species of Australian plants need particular care in their pruning. (So do exotics.) These are plants that flower on wood which is one-year old and older. One genus that immediately comes to mind is the Net Bushes, Calothamnus spp. These species generally require a light pruning immediately after flowering. The only other pruning that should be done is to
31 correct straying branches. This method applies to all plants that flower in this fashion. The final shape of many tree species can be spoilt if the leading or dominant stem or branch is removed. Most tree species will not need pruning until they are at least partially mature and this would probably only amount to the removal of lower branches, perhaps to accentuate the tree form. The only exceptions to this rule that I can think of are many of the mallee species of Eucalyptus. These trees will, when grown from seed, usually produce only one trunk. If a mallee is grown it is usually for its many stemmed character. After the tree has established itself the stem may be cut back to the lignotuber and shortly afterwards many of the dorm ant buds in the lignotuber will shoot. The number of buds that will regrow can vary greatly from species to species. Many of the shoots will die back after a time but unwanted shoots can be pruned out before this natural selection takes place and the desired shoots retained. Many other species of Eucalyptus and other genera also have a lignotuber or dormant epicormic buds which have evolved over the centuries as a survival mechanism against bushfires and other harsh environmental factors. If desired all these species can be lopped and the coppice shoots retained to form a new plant. This procedure can be repeated numerous times during the plant’s life. Root Pruning Root pruning basically accomplishes the same as top pruning. When roots are cut and the apical dominance removed it induces the growth of lateral roots. Root pruning should be carried out from the earliest stages of a plant’s development. This is particularly important when potting plants from container to container. When doing this, any root binding or balling should be teased out. If the root balling is particularly severe, then roots should actually be cut away with a sharp implement to enable quick re-establishment in the new container. I cannot recall how many instances of bad potting technique I have seen or been told about. The most common occurrence has been plants that have been grown in small containers and, when potbound, have been potted into a larger container to be grown on. Some small amount of root then broke free from the root ball and became bound in the larger container. This means that these plants have, in effect, got twice as much problem of binding as a plant grown in one container. The original problem is quite often not noticed or realised,
32 unless the plant is freed of all potting mix prior to root pruning and repotting. Presuming the plant is bound only in the final container before planting, root pruning can be a very simple process. If the binding is not too bad, all that is necessary is to tease out the roots at the bottom and sides of the root mass.
cut root system in shallow cuts around side of container
cut away badly spiralled roots at the base of the rootball
Root pruning
If binding is serious, then some of the roots may have to be completely cut away, particularly at the bottom where the curling will be more evident. Even taproots can be cut away with no detrimental effects. One or perhaps more roots will grow more vigorously to resume the function of the displaced tap root. However, there is one very important point that must be considered. If the root system is reduced in size in any way, compensation must be made by the reduction of top growth. The plant’s leaf area will still transpire and food production due to photosynthesis will still continue. When the root system is reduced in size it will not be able to cope with the demands for water and nutrient by the foliage. Therefore it is necessary that whatever percentage (an approximation will do) of the root system is removed the same proportion of the top growth is also removed, i.e. if one-third of roots are removed then one- third of the top growth is removed. This will minimise damage due to transplant stock.
33 Root pruning has been a well recognised procedure for plants grown in lined out situations for many years, particularly for advanced conifers and deciduous trees. It has the effect of producing more lateral roots and enables plants to be transplanted at much larger sizes. This also has advantages in the home garden. If a large shrub or tree is growing in an area where it is no longer wanted, or would be better growing elsewhere, it may be transplanted. Root pruning is carried out some six to eight weeks prior to moving. When the roots have had time to re-establish themselves a final pruning is done and the plant can be balled up and moved to its new site. At this stage compensatory top pruning is again in order. I have satisfactorily moved Callistemon and Melaleuca some two metres high by this method.
attempt to dig Ira. deep at the lowest point
Root pruning prior to moving a plant to another situation. This should be done 6-8 weeks before the moving is undertaken. Many authors have recommended that a plant should be removed from its container with minimum root disturbance at planting time. I feel this is very bad advice unless the root system is only just filling the container, but even then the roots should be loosened slightly when planting. Root pruning is essential as, if left undone, the plant will become prone to wind rocking due to the roots remaining confined to the pot’s shape. Even if wind does not destroy the plant the roots can become so bound up as they grow that they will choke the food conducting tissues and the plant will then assuredly die.
34 I thoroughly recommend root pruning at any repotting stage or when planting into the final position where the plant will grow to maturity. All forms of pruning, then, are an efficient way to help keep a plant the way you want it to look but it must be remembered that whatever the plant’s genetic components tell it to grow to will be the shape and height it will constantly try to attain. Pruning will not halt a plant’s growth; it will only arrest it for a short time. If you want a plant of a certain height and width in a particular situation and do not want to spend time pruning, be sure to plant a species that will attain only the height and shape you want.
35 Watering
When and why to water is quite often misunderstood. When establishing an Australian plants garden, many people believe that after the first year the plants will never need watering again, that they will be able to survive on the natural rainfall. Of course this is true of many species. They will survive, but supplementary watering will be necessary at some times during the year to achieve the best results from the plant. Usually in a garden you will be growing plants from many parts of Australia which naturally occur in differing environments. So some plants in your garden may well be accustomed to far more water than our average 675mm (27") rainfall. Also you may have plants from extremely arid regions where overwatering could become a problem. So this is where grouping plants of similar water requirements in the garden can be enormously beneficial. For instance many species of Boronia can be satisfactorily grouped together as they require approximately the same water regime for satisfactory growth. Arid or dry growing species can also be grouped together, but at the same time do remember that just because a plant comes from a dry or arid region does not mean that it will not benefit from supplementary watering during dry spells. The main factor governing supplementary watering is going to be the water-holding capacity of the garden soil. Gardens on steep slopes where runoff is high, where beds have been raised or where a lot of sharp sand has been incorporated into the bed will have to be watered more frequently than beds that are at existing ground level in flatter areas, or beds that have been improved with plenty of peat or other organic matter. The watering of any area will have to be tried and checked until the individual bed’s requirements are known and a general schedule of watering (allowing for day-to-day weather condi tions and seasonal changes) can be established. At any stage do not allow the water regime to fluctuate too widely. Most species do not appreciate such fluctuations. Health, vigour and the appearance of a plant will be maintained if such fluctuation does not occur.
36 Overwatering Constant overwatering can be very detrimental, particularly during warmer weather, resulting in a rise of activity of certain fungal diseases (see.chapter on diseases). Lack of soil aeration can also occur, resulting in plant death. Most species of plants do not enjoy having waterlogged root zones for prolonged periods and heavy watering carried out regularly will cause this and plants will be lost.
Underwatering Underwatering also has its problems. Light, irregular watering wrill result in more surface root formation. All plants have a certain amount of near surface roots but it can be accentuated with light watering. This can result in further problems during dry spells. If the top layer of soil dries out plants can wilt and so suffer set back. If left unchecked it can also result in the death of the plant. Surface rooted plants are also fairly unstable in high winds and may be blown over. Frequent, reasonably light watering has an advantage in germinating annual seed, directly sown in garden beds. Germinating seed must be kept constantly moist or they may dry out resulting in loss of the young plants. Even so, the soil must be moist to a suitable depth to encourage the root system to go deep. Water holding capacity of the soil can be altered fairly readily. If beds dry out too quickly, incorporation of peat moss and/or other organic matter can help to hold more moisture. If beds are constantly too moist, raising the beds by the incorporation of clean fill and/or river sand can aid in improving drainage. Mulch also helps to control fluctuation of moisture (see chapter on mulches). Dry weather is not the only time that watering may be necessary. During the winter months Canberra suffers from quite heavy frosts, sometimes for extended periods. Frosts dry out the soil and this moisture will have to be replenished periodically, Winds, both cool and warm, also increase the amount of water transpired from plants and watering will have to be supplemented from time to time. Watering off frost before the sun hits the plant can also to some extent help to prevent frost burning of plants.
When to Water This is a matter for individual gardens, but when it has to be carried out it is far better to soak the bed thoroughly and then
37 leave it for some time before rewatering. In my own garden I find that generally a thorough soaking once a week during the warmer months is sufficient. Most of the beds are raised from 15 cm to 30 cm with clean fill and river sand and are mulched to a depth of 5 cm.
Watering Equipment When purchasing hoses it is far better to spend the few extra dollars and purchase a good quality hose. Cheaper hoses perish much more quickly in our climate. Plastic reinforced hoses are by far the best buy. When the hose is not in use shield it from direct sun or frost, and the elements generally, and it will last for many years. A great variety of sprinklers are available and most are quite satisfactory for garden use.
38 Mulches and Mulching
A mulch is a protective covering that is laid over soil. It can be either an organic or inorganic material and both have various advantages and disadvantages which will be outlined later. Mulches are used for a variety of reasons. 1. To conserve moisture. Placing a mulch barrier between the ; soil and the atmosphere prevents excessive evaporation, thus retaining soil moisture for the plant’s use. This also helps to cut down on water usage by reducing the need for supplementary watering. 2. To keep a cool root zone. This is very important for growing many species of plants, for example, many members of the Family Rutaceae. The mulch keeps the soil cool and so provides a barrier between the soil and the sun’s rays. 3. To suppress the growth of weeds. No mulch will completely prevent weed growth but it certainly will help to keep weeds to a minimun. A good mulch will prevent weed germination by providing a barrier against weaker seedlings, preventing them from emerging through the mulch. Stronger seedlings may well break through but weeding will markedly reduce the problem. Most mulch layers remain dry on top and this also helps to prevent weed seed from germinating. 4. Plant nutrients. Organic mulches, or mulch derived from living material, can provide valuable humus to the garden soil as it gradually breaks down. Organic mulches also stimulate the growth and activity of earthworms and other soil micro organisms, which in turn help to incorporate the organic material into the topsoil. 5. Appearance. M ulches can be aesthetically very pleasing and various mulches can be chosen to suit various types of gardens. Pine chips and pebbles can look attractive for more formal gardens while eucalypt leaf litter blends well in more ‘natural’ gardens.
Advantages and Disadvantages of Organic Mulches Organic mulches are usually far better than inorganic mulches, providing a more natural appearance. Organic mulches gradually break down and become incorporated into the soil.
39 This action provides nutrition for plants but the mulch will have to be replenished occasionally due to this breakdown. When laying organic mulches the depth of the mulch must be watched. If laid too deep, a thick layer of fungus can build up in the mulch and prevent water penetration to the soil surface. These fungi are saprophytes and help to break down the mulch. They are not detrimental unless allowed to colonise the mulch too thickly. As organic mulches break down they use nitrogen from the soil and this has to be replaced at intervals during the year or soil nitrogen deficiency could result which in turn affects the plants. Nitrogen deficiency symptoms are explained in the section on fertilisers in the chapter on follow up maintenance. The best times to apply a nitrogenous fertiliser are in spring and early autum n when soil micro-organism activity is at a maximum and also when the plant’s need for nitrogen is at its greatest. The main fault I have found with organic mulches in suburban areas is the local cat population. As most suburban gardens consist ol large tracts of lawn, cats love to congregate and use mulched areas to ‘scratch in’. This can present problems of smell, especially during the warmer months of the year.
Advantages and Disadvantages of Inorganic Mulches Inorganic mulches are mulches of previously non-living material such as stones, pebbles or river sand. Once laid these mulches are permanent, as they do not break down and therefore do not have to be replenished at any time. Also, being inorganic, no problems of fungal growth are present so water penetration is not hindered. Stone or pebble mulches can provide problems with rotary lawn mowers if they are scattered. Sand mulch can also provide a digging ground for cats. Because inorganic mulches do not break down no nutritional advantage is received by the plants. To my mind inorganic mulches really do not blend as well in the garden as organic mulches.
Mulches readily available in Canberra Due to the large acreage of Pinus radiata forests and milling of these forests in the Canberra district, large quantities of pine chips and ‘tan bark’ mulch are available. Pine chips are a good mulch but should not be laid any thicker than about 2.5cm. If laid any deeper, serious fungal
40 buildup occurs, hindering water penetration. Pine chips do not break down rapidlv and so do not have to be topdressed for a considerable time. When purchased, the chips are relatively fresh and rather a bright yellow colour. This fades with age to a dull grey. Cats seem to relish these chips to dig in. Pine bark, more commonly known as ‘tan’ bark, is also available in large quantities. My experience with this material is that it has to be aged and leached before laying on the garden. The tannin that is leached out of pine bark appears to have deleterious effects on plants, if laid on the garden while fresh. Soil in my garden, dug over after fresh pine bark had been laid- some two years previously, was stained black with leachates and no plant in the bed has done at all well. This is an experience I have heard repeated a number of times from other gardeners in Canberra. Tan bark weathers to a silvery colour when exposed to the elements. Pine needles are obtainable locally. Needles make a good mulch but break down quickly and raise soil acidity very markedly. A newer product coming into Canberra is a by-product of the hardwood woodchip industry at Eden. Availability of these chips may be uncertain in the future. They are relatively inexpensive if purchased in bulk from the suppliers, but are much more expensive bought in smaller loads from local sources. The chips are an excellent colour- a rich brown fading to dull brown - and blend very well in any garden. There appear to be no deleterious effects if laid down while new. In some areas quantities of Eucalyptus leaf litter may be obtained. You usually have to gather it yourself but it provides an excellent mulch. As it is rather light it can be scattered in heavy winds. It also has to be replaced or topdressed more frequently than other mulches because it breaks down rapidly. Coarse river sand is very readily available in Canberra and environs. It provides a good mulch with excellent water penetration. It can look very stark, being whitish in colour. Weeds also germinate fairly well in this mulch. Cats and dogs find it particularly attractive for scratching in, and children tend to treat it as an enormous sandpit. River sand does not break down and if left relatively undisturbed should not need topdressing. River pebbles or stones are also readily available but are not often used as. a mulch. Water penetration is excellent and breakdown is nil. Scattering can be a problem with rotary lawn mowers as these machines are capable of throwing stones out
41 with a great deal of force and for long distances. Many people prefer to lay some sort of material under most mulches to prevent weed germination. The material most commonly used is black plastic but this is the one that I would totally avoid. Black plastic has many problems associated with it, not least being that the soil beneath loses its aeration. If it is to be used, and laid on a slope, care should be taken to ensure that the plastic is laid from the top of the slope towards the bottom to ensure that water is able to seep through to the soil. Surface rooting problems are worse under plastic than any other material. When plastic laid in a friend’s garden on a flat block was removed the soil was found to be very poorly aerated, due to waterlogging, and all the main roots of a 5m tall eucalypt were running along the surface of the soil directly beneath the plastic. This made for a very unstable tree, especially in strong winds. Underfelt or newspaper is probably the best material to lay under mulch. Both are organic materials and break down over a period of time and are incorporated into the soil. Lay newspaper approximately 10-15 sheets in thickness and overlap sheets by 7-10cm. Lay underfelt in a single thickness and also overlap by 5-10cm. When using underfelt be sure it is not the type that has a rubber backing. This material acts in the same way as black plastic sheeting. With a good mulch an underlayer is not necessary. So long as the mulch is of a suitable thickness problems of weed germination will be kept to a bare minimum. Two last points should be made about mulching. When laying the mulch, care must be taken not to build the mulch up around the collar of the plant. The collar of the plant refers to the stem or trunk from ground level to approximately 10cm up the stem of the plant. If the mulch is built up around the collar it can lead to a rotting of the plant tissues, destroying the cambium (or food conducting tissue) layers thus causing the death of the plant. Mulch should be cupped around the base of the plant. Second, if mulch is used, do not use a variety of different mulches over a small area as it looks very disjointed. Beds should be mulched throughout with the same mulch, as aesthetically it is more pleasing, and it also makes the area appear to be larger than it reallv is.
Living Mulches Ground covers can also be used as a mulch. I prefer to use them
42 wrong right
mulch layer (5-7cms. deep)
ground level
mulch should always be cupped around the plant collar, never built up around it
in conjunction with a normal mulching material. If ground covers are to be used the depth of the normal mulch can be halved. Some species ‘sucker’, i.e. produce new growths on rhizomes or stolons and many of these are extremely vigorous when used with or without normal mulching material. Other species grow from a central stem and spread outwards over mulch. Both types provide an extra barrier against evaporation and weed seed germination. With living mulch senescing leaves drop and add to the normal mulch cover. The best living mulches are fairly shallow rooted with extensive rhizome or stolon capabilities. The main drawbacks to living mulches are that they have to be fed, need extra watering due to transpiration, draw nutrient from other plants and, in many cases, are not able to take regular or heavy traffic. In their favour is the aesthetic appeal of their extra greenery. They are suitable and attractive to use in conjunction with normal mulching materials.
43 Propagation
Contrary to popular belief, the propagation of Australian plants is no different from propagation practices and techniques applied to exotic plants. For some species slightly more sophisticated methods and equipment are helpful, particularly in vegetative propagation, but counterparts can also be found in the exotic world where the same methods and equipment can be used to advantage. Much has been written on propagation in this country but for some amazing reason many authors still include a separate chapter in these texts on the propagation of Australian plants from seeds and cuttings. One text I have seen mentions only five genera of Australian plants as suitable subjects to be grown from cuttings. This is a deplorable situation and one which I hope can be overcome as soon as possible. Horticulture is an inexact science, so there may be many differing ways of accomplishing the same end result. This applies to propagation. The methods outlined in the following pages are extremely efficient for growing plants in Canberra. At all stages of propagation work cleanliness is essential. This applies to all materials, tools and equipment that are used. Examples of cleanliness will be cited where necessary in this chapter. Cleanliness will minimise problems caused by certain ‘dam p-off fungal contaminants, and will enable good results in propagation to be attained. All the materials mentioned are freely available in Canberra.
Seed Propagation Australian plants have a tremendous variety of fruits and seeds. 1. Berry or fleshy fruits: These have seed or seeds enclosed in a succulent outer covering. Many of these are edible and can be very attractive to animals and birds. This is one of the ways in which these seeds are dispersed. Sollya, Solanum, Eugenia, Enchylaena, and Dianella are examples of fleshy fruits. 2. Capsular fruits: These are typical of a great many species of Australian plants. They are hard woody fruits which can be held for many years on the plant. Many members of the Myrtaceae family including Eucalyptus, Callistemon, Melaleuca,
44 Leptospermum and Calothamnus have capsular fruits. 3. Pods: Everyone is familiar with the fruit of the domestic garden pea. This pod-type fruit is characteristic of the Fabaceae, Caesalpiniaceae and Mimosaceae families including such genera as Acacia, Cassia, Oxylobium, Pultenaea and Harden- bergia. 4. Follicles: Once again these are woodv-type containers which can vary greatly in form. They are a characteristic of the Proteaceae family which includes Banksia, Hakea, Telopea, Lomatia and Lambertia. 5. Cones: These are found on species of conifers such as Callitris. 6. Achenes or Pappus: These are seeds which are attached to a ‘feathery’ or similar appendage which is very light and are dispersed by wind. Examples are Helichrysum, Helipterum, Olearia and Clematis. When collecting seed there are a number of important points to remember. Always collect seed from healthy plants. A vigorous plant will usually have healthy, well-formed and viable seed. It is also important to collect seed from reliably named plants. When collecting seed in a garden where two or more species of the same genus flower at the same time there is always a possibility of hybrid seed being collected. Grevillea and Callistemon are notorious for this. It is, however, important to know what species you are growing, and collecting seed from reliably named plants is one method of achieving this. As soon as seed is collected it should be labelled and dated. Do not rely on your memory, especially if seed is being stored. Dating seed is important where the viability of the seed is short. The place from which the seed was collected should also be marked on the label so that more seed may be obtained in the future, if it is required, and, having recorded the date of collection, you will also know the suitable time of the year for collecting seed of that species. Seed should be collected when it is mature. If it is picked too early, it may not germinate. Some plants shed their seed as soon as it is ripe and this can vary from a few weeks to a few months after flowering. Other species will hold their fruit for many years until some adverse or catastrophic happening - drought, bushfires or a limb dying or being broken off the plant- causes them to be released. These factors cause the fruits to dry out and the seeds are released from the fruit. To collect from species that shed seed as soon as it is ripe, you will have to be
45 there to collect it at the time. From species that hold seed for a longer period it can be collected at any time. In this instance select fruit from lower down on the plant as it is more likely to be mature. These fruits should be at least twelve months old to be mature. Seed Extraction. The majority of seeds, once shed, may be stored, or sown more or less immediately on collection. The woody fruits, however, are a different matter. When these fruits are collected, they may take some time before they dry out enough to open and release the seed. This process can be speeded up by placing the fruits in a paper bag and leaving them on a warm window sill or similar sunny spot. As the fruits dry out they open and release the seed. Even if the fruit does not fully open the seed is usually easily prised out. Banksia are very quickly opened by placing them in a metal dish and pouring methylated spirits over the fruit and igniting it. This causes the rapid drying and opening of the follicles. A gas blowtorch can also be used in the same fashion. Care should be taken with many of the Proteaceae family when seed is extracted that it is not the winged divider that is thought to be the seed.
Banksia fruit The seeds are the papery winged objects on either side of the divider. Quite often only one of these seeds will be properly developed. Developed seeds be distinguished as they appear as a substantial swollen end on the papery wing.
46 Seed Viability. Seed viability varies from species to species. Many annual species lose their viability very quickly. Annual Helichrysum have an excellent viability in the first year after collection but then it drops away very markedly in successive years. Other species may remain viable for many years. Even very fine seed such as Eucalyptus and Leptospermum obtained some forty years after they were collected have proved to be extremely viable. As seed viability varies so greatly, it is an excellent idea to keep a small notation of approximate viability periods for various genera or species to use as a guide, though with most bought seed or fresh seed you have collected no problem with germination should be experienced unless other factors such as chemical inhibitors or seed dormancy is involved. Seed Storage. Seeds are best stored in cool, dark and dry conditions. This helps to prolong the viability of the seed to a maximum. Seeds should be dried and stored in clean glass containers (baby food jars are excellent), paper bags or envelopes. Plastic bags should not be used as long-term containers for seeds. Fleshy seeds should be cleaned of the succulent outer layer before storage or they will rot. When storing seeds, it is a good idea to dust them lightly with a DDT- based powder. This will prevent insect attack while they are stored. Seed Growing Systems. There are two main methods used for growing seeds. These are by overhead watering and by bottom watering, more usually known as the capillary system. With overhead watering punnets are simply watered with a very fine spray of water, usually from watering cans fitted with very fine nozzles. These are available in Canberra but are very expensive. Overhead watering is efficient for larger seeds but can result in the disturbance of smaller seeds while they are germinating. The capillary system is a system where the punnets are placed in a tray or other container which has a reservoir of water and the water is drawn into the seed punnet by means of capillary action. This system is suitable for growing all seeds, especially very fine seeds, as they are not disturbed by water splash on the surface of the punnet while they are germinating. The water supply to the seedling is also constant and does not fluctuate as it does with overhead watering. This system is also self- maintaining for extended periods of time, depending on what sort of volume of reservoir-refill mechanism is employed.
47 More sophisticated capillary systems have a reservoir similar to a toilet cistern which is replenishing the w ater supply constantly while others depend upon bottles or flagons which have to be refilled occasionally. I strongly recommend the capillary system for growing seed.
reservoir _
p u n n et fine gravel
Capillary Tray water level
Seeds can also be germinated in other ways. They can be pre germinated by placing them in moist canvas and rolling the canvas up until the seed has germinated. Empty egg cartons are also useful. Two bottom halves of the cartons are moistened, the seeds sown into the ‘cups’ of one half and the other half carton is then inserted into the first half in which the seeds have been sown. This keeps the seed moist until germination takes place. Some seeds can also be sown on moist tissue paper placed in a saucer. When germinated they are potted. With all of the last three methods, only larger seeds such as Acacia, Clianthus, etc. are really suitable for use. When sown they should be placed in a warm position and should be checked at least every three days to a week. Once germinated they can be potted. Seed Sowing Media. Many materials can be used or mixed with other materials to germinate seeds. The type of medium used will depend on what system is used to hold the punnets while the seeds are germinating. If using the capillary method, moisture-retentive materials such as peat moss, vermiculite, soils or loams should not be used as these will cause the seeds to rot, due to too much water being held in the seedling’s vicinity. It can also increase the chance o f‘damping off diseases once the seed has germinated. If overhead watering is used then these materials can be used to reduce the fluctuation of the water regime. Fluctuating water levels can greatly impair seedlings during and following germination. A good sowing medium should be well aerated and reasonably water retentive, but excess should be able to drain away quickly. It should also be of a friable nature to enable the
48 easy removal of seedlings when pricking out, thus minimising damage to root systems. It should also be clean. Cleanliness can be achieved by using reasonably pure materials, chemicals or by heat sterilising. Fungicides can be incorporated into the seed m edium while mixing. Le-San is very suitable for this. Heat treatment involves placing a small quantity of the medium in an oven pre-heated to 60°-65°C and held at this temperature for half an hour. It is then rapidly cooled and used. For use in capillary systems, 100 per cent river sand is very suitable. River sand used in conjunction with perlite of up to 50 per cent content of each is also very suitable. For overhead watering 50 per cent of river sand and 50 per cent peatmoss, or vermiculite or thejohn Innes Composts can be used. Fertiliser is not necessary in seed growing media as the endo-sperm of the seed contains enough food to meet its requirements until potting, providing potting takes place as soon as the seedling is large enough to handle. Seed Pre-Sowing Treatment. Many species of seeds can be sown directly into punnets but many others require some form of pretreatment before sowing to aid the rate of germination. The main treatments are mechanical, chemical, stratification, heat and washing. With mechanical treatment the seed testa or ‘coat’ is either scratched, clipped, scarified or cracked by some mechanism such as files, sandpaper or nail clippers to enable water to penetrate the testa to ensure germination. Some species require a cold moist stratification period before a good rate of germination will take place. This can be achieved by placing seed in a refrigerator for three to four weeks before sowing. Many species from cooler climates require this treatment before sowing. Chemical treatments normally entail the immersion of seeds in a dilute hydrochloric acid bath. The time of immersion will depend greatly on the thickness or durability of the seed coat. Hot water (heat) treatment is used to break the seed coat of many plants. It works particularly well with members of the Fabaceae, Caesalpinaceae and Mimosaceae families. All that is required is to pour boiling water on to the seeds and then leave them to soak for about one hour. Repeat treatments may be necessary for those seeds w'ith very thick or very strong seed coats. The seeds should not be boiled as this will lead to permanent damage or destruction of the plant embryo. Washing of seeds can be useful where a germination inhibitor usually chemical and very hard to isolate and identify
49 is present on the seed. The easiest method of achieving this is to hang the seeds in a cloth bag which is placed in a lavatory cistern. With the constant draining and refilling of the cistern over a period of three to four weeks, the water will leach the inhibitory substance and seeds can then be sown normally. Seed Sowing Methods. When sowing seeds a number of details should be watched. Seeds are best covered after being sown. A good general rule is to cover the seed to a depth twice that of its diameter. Cover very fine seed with a bare minimum of fine-particled sand. Some seeds, especially Acacia, are best sown four times as deep as the diameter for best root formation. Do not oversow seedlings in the punnet. With fine seed a good pinch of seed scattered evenly over the surface of the punnet is sufficient. The larger the seed the fewer that should be sown. Of the larger seeds such as Banksia, Grevillea and Acacia approximately 30 to 40 seeds is a good number to sow in the normal seed punnet. The more thickly seeds are sown the more likelihood there will be of the outbreak and spread o f‘damp off disease. To help reduce the outbreak of fungal diseases the seeds can be dusted with a fungicide powder before sowing. The seeds are placed in a paper bag with a small amount of fungicide powder and are shaken around. This coats the seed with a layer of powder which will be active while the seed germinates. This method is really only practical for larger seeds. For outbreaks that occur while in the punnet, isolate the punnet immediately, especially if it is in a capillary tray. Either dispose of the punnet or spray with a fungicide. Captan and Thiram are very suitable for this purpose. Many seeds may be sown directly into the containers from which they will be planted. Eucalyptus, Acacia and Casuarina and many others can be treated this way. It is best to sow two or three seeds in the centre of the pot. These are then covered and kept moist. Once germinated the strongest seedling is selected and any others are culled out. Requirements for Seed Germination. There are three main require ments for satisfactory germination: oxygen, moisture and warm temperature. Oxygen is normally no problem as long as the medium is well aerated. Moisture should be constant, fluctuating as little as possible. Temperatures are best if reasonably warm and fairly constant. The seed tray can be situated anywhere that is reasonably sheltered from wind and rain. A situation that is semi-shaded is ideal. If direct sun is received it should only be morning sun as
50 afternoon sun may burn the seedlings. Pricking out of Seedlings. After germination seedlings should be pricked out as soon as they are large enough to handle. Even small seedlings are easily handled at about 5-7mm in height. Larger seedlings can be transplanted at the cotyledon (seed leal) stage. When pricking out, the seedling is gently prised out of the seed mix. If the root system is large it can be pruned back. (See root pruning in chapter on pruning.) A hole is bored into the medium to accommodate the seedling, which is placed into the hole, making sure that all the roots are pointing downwards. If the roots are thrust upwards, this will lead to a malformed root system or they could die back and add to the transplant shock effect. The soil is firmed around the roots and it is essential that any hollow beneath the seedling is also filled. If this is not done the seedling may sink when it is watered in. The seedling, when potted, must be at the same depth as it was when removed from the seed mix. Watering-in should be carried out as soon as possible after potting. The seedlings should be gradually hardened off in a semi-shaded position and gradually introduced to full sun. Plants in containers can be pruned for shape from an early stage, starting from the potting stage. While being held before planting out, make sure that the plant is kept free from diseases and pests. Most plants will be ready for planting approximately nine months after potting. The only other point to add about seed growing is that plants, when grown from seed, are subject to what is known as seedling variation. This can be useful when developing new forms or hybrid plants, but where certain forms or characteristics are desired to be kept, vegetative propagation is the only sure way of achieving this. I strongly recommend the growing of plants from vegetative material wherever possible.
Vegetative Propagation Vegetative propagation, or asexual reproduction, involves the reproduction of plants from the vegetative parts of plants, which have the capacity for regeneration. These vegetative parts can be the roots, bulbs or bulbous rootstocks, rhizomes, stolons, stems, leaves, buds or even flowering stems. Today, much work is also advancing into the realms of grafting work and tissue culture on Australian as well as exotic species. But why bother with vegetative propagation when growing plants from seed is so relatively easy? The reasons for asexual as compared with sexual propagation are:
51 1. Vegetative propagation allows for, in many cases, a uniformity of strike rate and growth rate, thus providing plants of uniform sizes. This is more important for commercial growers than for the home gardener. 2. Vegetative propagation maintains plants of a particular genetic makeup. These plants will have the same genetic characteristics as the parent plant. This aspect is essential in the ; preservation of certain desirable forms and characteristics in plants, particularly cultivars or hybrid material. 3. Some plants do not set seed easily or the seed viability rate is low, thus vegetative propagation is used. 4. Vegetative propagation allows for earlier flowering as the new plants do not have to go through the juvenile stage of growth that a seedling does. 5. Many seeds have slow germination rates or may grow slowly after germination whereas cuttings of the same species may strike well and grow rapidly after potting. 6. Seeds can usually only be collected once a year whereas some cutting material is available at most times during the year. Types of Vegetative Propagation Cuttings are pieces of vegetative material that are separated from the parent plant and placed into a rooting medium to form a number of plants of the same genetic makeup as the parent plant. Cuttings are by far the most commonly used form of vegetative propagation, and there are many varied types of cuttings. 1. Hardwood cuttings: mainly used to propagate deciduous species and taken when the plant is dormant. The material used is usually the previous season’s growth. This method is not used to any great extent with Australian plants. 2. Semihard or medium wood cuttings: these are probably the most common cuttings used and they are prepared from material just after a strong flush of growth, e.g. spring, when the newly grown wood has had time to partially mature. These cuttings are commonly taken from December through to March in our conditions in Canberra. Medium wood cuttings are commonly taken from approximately 5cm to 15cm long. The leaves are trimmed off at the basal end for a half to two-thirds of the length of the cutting. If the species being propagated is a large- leaved one, the remaining leaves can be reduced in surface area as at no time should the transpiration rate exceed the amount of water the cutting is able to absorb. This last action can also vary depending on the conditions the cuttings are going to be
52 kept under while root formation takes place. With medium wood cuttings it is preferable to keep the shoot terminal intact as this will provide a ready growing point. The basal cut is made just below a node. The reason for this is that root initiation and callousing of the cutting occurs more readily in this region of a plant’s tissue. I should mention here that when cutting wood is removed from a plant it should be kept cool and moist at all times and, if possible, prepared soon after being cut. The best way to store cuttings is to wrap them in damp newspaper, but do not wrap them too tightly as they are likely to sweat. Keep the wrapped cuttings as cool as possible and process as soon as practicable. 3. Soft Tip Cuttings: are also used fairly often with Australian plants. These cuttings are prepared in the same fashion as medium wood cuttings from material that is actively growing, and is usually taken during the spring months. Vigorous, fast growing shoots are best avoided for obvious reasons. To select good softwood material, choose that wood which breaks when it is bent sharply downwards. This material should be collected in the cool of the morning for best results and should be prepared as soon as possible after collection. Softwood material can wilt extremely quickly and it is acceptable practice to nip out the terminal shoot if it does wilt. These cuttings are usually made from 7.5-12.5cm long. Softwood cuttings require much better housing than medium wood cuttings. They are sometimes classed separately from herbaceous tip cuttings but for all requirements of growing they are the same. Bottom heat is required for the fully satisfactory growing soft tip cuttings and mist can also be useful for many species though it is not essential.
leaves removed from ^ close to stem
branch showing where B. heel cuttings are rem oved Tip and heel cuttings There are two methods of taking these cuttings. The stem cutting has been fairly well explained but another commonly used cutting is known as a heel cutting. This is a lateral branch that is taken off with a small portion of a main stem attached to the basal end. Other forms of cuttings such as leaf cuttings, leaf bud cuttings and root cuttings can also be used to propagate some species of plants but are not within the scope of this book. Division is a very effective method of plant propagation which simply means that more plants are propagated by breaking apart certain parts of plants such as tubers, rhizomes or clumps. Some plants that can be propagated by this method are Dianella, Patersonia, Orthosanthus and Anigosanthos. Once the pieces of plant are separated they are potted or planted out separately and will develop into new plants. Division is best carried out during autumn. Layering is also a very useful method of propagating plants. Layers are where roots are formed on vegetative material while it is still attached to the parent plant. There are five main types of layers: simple, aerial, continuous, compound and mound layers. The two main layers used are the simple and aerial types and these are best shown by diagrams.
inset
inset
Simple layer
54 Simple layer. This is where a branch is bent down andfirmly secured to prevent any unnecessary movement. The stem is cut halfway through and along the stem for 5 cm. This cut can be treated with hormone solution if desired. The layer from cut to tip should be 20-30cm long. It can also be made in a submerged pot for ease of transplanting. Roots form in the cut region. The layer should be made in a good quality soil or potting compost.
i Aerial layer Aerial Layer. This layer is done on branches to 2cm in diameter. The branch is cut in the same manner as for the simple layer. The cut can also be treated with hormone and is held apart by placing some sphagnum moss in the cut. The cut is then wrapped in moist sphagnum or peat moss and then wrapped in alfoil or similar reflective material. A plastic wrapping is then placed around the layer to keep moisture in. It can be checked \ occasionally for root formation. Once roots have formed the branch is cut where the dotted line is shown, the plastic and alfoil is removed and the layer is then potted as for other cuttings. Grafting and budding are more specialised methods of producing plants by vegetative means. Both grafting and budding result from the joining together of pieces of two different plants in such a way that they combine together and grow and function as one plant. Grafting and budding can be used to meet various requirements, probably the main one being the provision of a hardy, reliable rootstock for a normally temperamental species. A good example of this in Australian plants is the grafting of Prostanthera, or mint bushes as they are ; commonly known, onto rootstocks of Westringia fruticosa, the Coastal Rosemary. Prostanthera generally are difficult to grow in Canberra but when grafted onto the hardy Westringia rootstock they have proved extremely good garden subjects.
55 Grafting can also be used for repairing damaged plants. There are many types of grafts, far too many to explain in this book. There is also a huge potential field in horticulture opened to us in the grafting of hard-to-grow species of Australian plants. As far back as the 1850s in Britain certain members of the Rutaceae family were being grafted onto Correa alba rootstocks. Much of this old information is now coming to light as people start to look at grafting our own hard-to-grow ornamental plants. As grafting is a complicated and large subject and also not within the scope of this book I would recommend most highly the text Plant Propagation - Principles and Practices by Hartmann and Kester for those who wish to pursue the practice of grafting and budding further.
Why do Cuttings do what they do? In short, most of what we know about the rooting of cuttings seems to be supposition in conjunction with some factual knowledge of hormone and auxin flows in plant materials. At certain times of the year certain natural growth regulators in plant material occur in certain concentrations beneficial to root formation. One of these natural growth regulators found in plants is Indoleacetic Acid, more commonly known as the abbreviation IAA. Research during the 1930s found that Napthaleacetic Acid (NAA), a synthetic but closely related substance, helped root initiation in cuttings at a much quicker rate. Combinations of certain growth regulators lead to the formation of ribonucleic acid (RNA) which is involved in the formation of root primordia. Many people still believe that a callous has to be present on a cutting as new roots arise from the callous. The callous tissue is actually just a healing of wounded tissue, much the same as the scabs that form on human wounds. Roots actually arise deep within the pith of the plant and then make their way out through the callous. Some species form exceptionally hard callouses which can limit root penetration through it. In these cases the cutting can be removed from the mix, the callous cut off and the cutting replaced in the medium. The pH of the cutting mix can also be a major factor in how hard the callous formation will be. A pH of 6.0 to 7.0 is the best. Most hormone treatments that are applied to cuttings contain I BA and NAA and they can be applied in either liquid or powder forms. These are available or can be made up to varying strengths depending on the type of cutting material to
56 be used. A number of powder hormones are readily available from garden centres and nurseries. Some growers also like to apply a fungicide powder to their cuttings before insertion into the cutting medium though this is not essential.
Mediums for Cuttings A good cutting medium should be clean, moist, well aerated and well drained, also one which breaks apart easily when unpotting rooted cuttings. There are many materials which can be used in the mixing of cutting mediums. Some of these are t river sand, perlite, peat moss, scoria, vermiculite and polystyrene I balls. A particularly good mix to use is equal parts of river sand, ' perlite and peat moss. This mix fills all the requirements of a good cutting mix. As perlite can be hard to obtain a good substitute is one-third peat moss and two-thirds river sand. Both of these materials are freely available locally. As mentioned before the best pH for cutting mix is between 6.0 and 7.0. When placing the medium into the pot do not compact it too much as this could lead to reduced root penetration into the medium and therefore slower growth.
Potting of Cuttings Potting is also a process that has to be done carefully to ensure quick recovery of the plant after depotting and repotting. A plant suffers from what is known as transplant shock during this process. Great care must be taken to ensure absolute minimum damage to the new root and shoot growth. Many plant families, e.g. Epacridaceae have extremely brittle root systems which can be snapped off very easily. Care must be taken not to push and bruise the roots when backfilling the pot and they must be laid carefully out and pointing in the right direction, i.e. downwards, when the pot is backfilled. The I cutting must be backfilled to the same level on the stem as was covered in the cutting mix. Container size when potting will depend greatly on the size of the root system on the cutting. Some cuttings throw out one or two very long roots whereas others will throw out a mass of shorter, more fibrous roots. I Long roots may be pruned back before potting on. This will induce more lateral roots to shoot. The size of container to use varies considerably with the vigour of the species being potted and how long the plant will be left before either repotting or ! planting out. The cuttings, when potted, should be watered in as soon as possible. After potting, the cuttings should be
57 hardened off slowly by placing them in a shaded position or in a hardening frame and preferably only exposed to full sunlight gradually. Plants should be left in the final container for about six to nine months before planting. Once again this is a general rule only. While holding the plants for growing on avoid hot or drying winds and drying out. From the potting point onwards, tip pruning at different times does not go amiss, to shape the plant, especially if the cutting, as many do, just grows quickly upwards with one leader stem. While in the nursery, keep the young plants free from pests and diseases as these can slow down the period from potting to planting considerably by reducing plant vigour and causing damage to plant tissues. Follow-up pruning after planting can also be performed. Contrary to popular belief in the past, native plants do respond to pruning as well as any exotic plant. (See chapter on pruning.)
Housing of Cuttings There are many satisfactory ways of housing cuttings until root formation has taken place. The main thing to remember is that the housing should keep a reasonably humid atmosphere around the cuttings. Below are diagrams of various methods of housing cuttings.
sheet of glass or plastic
wood or metal box
river sand
plastic bag placed over top of pot
cuttings set in pot
Simple housing for cuttings
58 Cuttings, when housed, should be kept in the same sort of environment as a seed tray is. More sophisticated equipment is also available for those people who require it. These include automatic mist systems and thermostatically controlled heating cables. A good insight into these systems is also given in Hartmann and Kester. It must be remembered that the growing of all plant materials follows certain general rules whether they are ‘native’ or exotic species, though the potential for horticulture of many Australian plants has still yet to be realised. Many of these plants will be shown to be good horticultural subjects, thus enabling people to get to know some of their natural heritage and help to conserve many species from possible extinction.
59 Pests
Most plant pests come from the insect world, a world that is very large. Only a minority of insects are pestiferous. Indeed, many are essential to the continuation of plant life as they are the pollinators of flowers. By far the greater majority of pests on Australian plants are native species of insects. Many of these are highly specialised and adapted to feed on certain species of plants but others have a wide range of host species. All plants are going to be affected by some pest species at times. In my view we should accept a certain am ount of damage to our plants and avoid the indiscriminate and widespread use of pesticides. There will be times, however, when they will need to be used, mainly when the pest population reaches such proportions that the plants’ health may be seriously impaired and physical control is impractical. It has been said that planting Australian plants will make pest control unnecessary, that biological control from birds and predatory insects will keep pestiferous populations under control. This is a fallacy: biological control cannot be efficient in such a biologically disturbed area as a suburb or city. Any garden owner has, I feel, an obligation to all neighbours to keep pests under a reasonable degree of control, whether by physical or chemical means. Garden hygiene is essential in keeping insects at bay. Do not provide places where insects can be harboured or breed. Clear rubbish before it builds up too high: at all times control is better than cure. Pests can be divided into four main types: leaf eaters, sapsuckers, gallformers and borers or tissue feeders. Leaf eaters: cover a diverse range of species and damage can take varying forms from skeletonising to complete leaf removal. When in plague proportions plants can be completely stripped of foliage. This results in an inability to manufacture food in the plant and the consequent reduced vigour enables secondary attacks by other pests. Some of these pests are: Chrysomelid beetle. Both the larvae and adult of this small beetle attack the leaves of both eucalypts and acacias. They rarely cause serious damage unless in very large numbers. There are a number of species in Canberra. Eggs are laid on the leaf surface
60 and when hatched, a small larva emerges. The larvae are small with a large black head and tail and a number of dark protuberances down the side of their body. When ready to pupate, they drop to the ground. After a short while the adult beetle emerges. This is about the size of a lady bird beetle and can be of various colours. Larvae are gregarious to a large extent but the adult is more of a loner. Chemical control is usually not necessary unless they are in large numbers. Control can be effected by the use of Malathion or Carbaryl.
[ Chrysomelid beetle Scarab beetle Scarab beetle. The most common scarab beetle in Canberra is the one more commonly called the Christmas beetle. The larvae feed in the soil on the roots of plants. Pupation also takes place in the soil and adults emerge in December and January. Eucalypts are the main victims and at times severe defoliation I can take place. Control is best by using Rogor 40 or Malathion. Leaf Blister sawfly. The larva of the leaf blister sawflv emerges from an egg laid by the adult inside the leaf. After emergence the larva eats the tissue between the surfaces of the leaf, leaving it with a blistered appearance. As the insect is well protected between the leaf surfaces a systemic spray has to be used to bring it under control. Rogor 40 is suitable. Gregarious sawfly. There are a number of species of gregarious sawfly found here. The commonest is the steel blue sawfly. The larvae are the harmful stage and can be recognised as they form clusters containing large numbers during the daylight hours and disperse to feed during the night. When disturbed the larvae raise their heads and exude a fluid from their mouths, a habit that has earned them the name ‘spitfires’. Because they cluster together they can be removed by hand and disposed of, they can also be sprayed, if accessible, with a household insecticide spray or controlled with the use of Malathion. Plants more commonly attacked are Eucalyptus, Melaleuca, and [ Callistemon and some others.
61 Typical sawfly larva Cup moth larva
Callitris sawfly. This pest, even though fairly gregarious, is mentioned separately as it is a specific pest to cypress pine trees. It has also been known to attack some exotic conifers. Once again, the larvae cause the damage and they are easily recognised by their green bodies and black heads. Defoliation caused by this pest is extensive and very rapid. Control is by Malathion. Leaflminers. These occasionally occur and do the same type of damage as the leaf blister sawfly, except that a zigzag type of pattern is formed on the leaf instead of a large blister. Control, once again, has to be systemic and Rogor 40 is suitable. Webbing caterpillar. Some years ago this pest was not particularly prevalent in Canberra. But with the large number of smaller leaved plants from the Myrtaceae Family that have been planted in both public areas and private gardens its numbers have grown alarmingly. It is and will continue to be a major problem with growing these plants in Canberra. During daylight hours the larvae rest in a webbed ‘cocoon’ built on lower branches or deep inside the foliage of the plant. At night they come out to feed. Webbing caterpillar can also attack other plant families e.g. Proteaceae. They can be controlled by removing the webbing by hand or by spraying the plant with Carbaryl or Rogor 40. Cup moth. This insect is so called because of the distinctive shape of the pupal case. Young larvae skeletonise the leaves and as they grow older the whole leaf is eaten. Serious infestations have been known to defoliate trees. The larvae are flattish and rectangular in appearance with a number of spine-like protuberances along the side of the body. They have two clusters of bristles at either end of their bodies. If these bristles
62 come into contact with skin the sting can be painful and lasts for about half an hour. Cup moths can be controlled with Malathion or Carbaryl. Case moths. These appear occasionally but do not do severe damage and are not worth major control measures. The larva builds a small cocoon out of twigs or leaves and sometimes sandy particles, as a shelter which is carried around with it. Only the head and thorax of the larva protrude from the case. It feeds on foliage of a number of species of plants. If control is desired Malathion or Carbaryl can be used. Skeletonising moth. Once again, these appear occasionally and attack mainly eucalypts. The larvae move across the leaf and eat the surface of the leaf, leaving the network of veins intact. I Control is by Malathion or Rogor 40. Sap suckers. Basically, these are insects with a long proboscis which penetrates plant tissue and sucks nutrition from the plant.
Aphids. There are a large number of species of aphids. They can be found in many colours from black to green and can infect a wide range of plants. They are usually found on the more succulent or new growth of plants. Aphids can do serious damage to the growing tips of plants and to foliage still contained within a bud. Aphids are easily controlled with Malathion or a Pyrethrin spray. Scale insects. There are many and various scale insects. Some of the m ore common ones are the oyster or cyclopsean scale, brown scale, cottony cushion scale and white wax scale. Scales all form a protective shell over the top of themselves. They can cause malformation of apical shoots and premature leaf drop and a lack of plant vigour. Scale can sometimes be hard to find. However they secrete a ‘honeydew’ solution which ants find very nutritious and so infestations can sometimes be found by following an ant trail up a plant. Any of the secretion which falls
63 onto leaves or stems develops a fungal growth commonly called ‘sooty mould’ w'hich can also indicate a scale infestation. Scale usually appears as small brown to white bumps on the stems and leaves of plants. Due to their protective covering they can be hard to control. The best time to spray is when the ‘craw'lers’ or young scale emerge from the parent scale ready to establish themselves elsewhere on the plant. Control can be effected by the use of a mixture of Malathion and white oil, or Rogor 40.
Leaf hopper Mealy bugs. These are small insects that cover themselves with a white, cottony exudation. Mealy bugs are usually found packed into the axils of leaves or in sheathing leaf bases. Affected plants show' a reduced vigor. Mealy bug can be controlled by spraying with Malathion, a mixture of Malathion and white oil or Rogor 40. Psyllids or lerps. These insects affect a wide range of plants, particularly eucalypts. Most species of psyllids build a cover over themselves under which they shelter while feeding on leaves. Heavy infestations have been known to kill mature trees. Trees that are heavily infested can have a silver)' appearance as the leaves move in a wind. These pests have to be controlled by using a systemic spray such as Rogor 40. Thrips. Once again there are many species which affect a wide range of plants. Their activity usually results in leaf senescence, malformed apical shoots and, in some instances, galls. Control is by spraying with Malathion or Rogor 40.
Acacia bug damage Eucalyptus thrip Leaf hoppers. These bugs feed on stems and leaves. There are a large number of species and a correspondingly large number of host plants. Sooty moulds and ants may also be found in conjunction with them. Damage caused by leaf hoppers can result in stem tip dieback and malformed apical shoots. Leaf hoppers are very mobile and quickly move around stems or branches so they are out of sight, they can also jump considerable distances out of harm’s way. Most leaf hoppers have a distinctive broad head and tapering, triangular shaped wing cases. Species can vary greatly in colour, from green to black and with various combinations of highly coloured spots. Because of their mobility, they are best controlled with a systemic such as Rogor 40, though a contact spray such as Malathion is useful when the insect can be reached. Gall formers. A large number of insects attack plants and feed within their tissue. The plant produces malformed, hardened tissue around the insect to protect itself. Usually the shape of the gall is a characteristic of the species attacking the tree. As gall formers are feeding within plant tissue control has to be by use of a systemic spray, Rogor 40 is effective. Borers. Very many insects, particularly moths and beetles, damage plants by boring in the conductive tissue layers or in the heartwood, which structurally weakens the affected plant. Tunnels and cavities left by borers can increase a plant’s susceptibility to further insect attack, fungal infestation and wind. Borers feeding in conductive tissues can result in the virtual ringbarking of a tree. Borers include such insects as longicorn beetles, weevils, wood moths and jewel beetles. Very little control is possible other than to clean up the damaged area and paint it over with a bituminous sealing paint. If the insect has not penetrated too deeply or too far into the plant it can sometimes be killed by inserting copper wire into the tunnel and killing the larvae. Mites. A number of species of mites can occasionally infest plants. Mites are usually microscopic in size and infestations will not usually be seen until damage is done. Mites can cause severe leaf mottling, sometimes resulting in leaf drop, and can cause damage to terminal shoots. Infestations can usually be noticed by a ‘spider web’ appearance underneath a leaf. Control is by the use of Kelthane or Karathane. Snails and slugs. These pests are well known by everybody and so is the damage they do. Control is best achieved by use of the commercial snail and slug baits such as Defender or Baysol.
65 Tree injection. Controlling insects in large trees can present problems. Today, instead of spraying, tree injections are becoming a more popular way of treating these plants. Tree injection involves the drilling of a series of holes around the trunk near ground level and the insertion into these holes of a systemic insecticide. The diameter and depth of these holes are fairly critical and, unless you are experienced, injection should not be undertaken. Certain systemic pesticides can also affect some species of trees and a thorough knowledge of this form of chemical control should be acquired before it is undertaken. Whenever pesticides are reverted to they should always be applied at the manufacturer’s recommended rates. Handling of the pesticides should closely follow that outlined in the chapter on follow up maintenance as applied to herbicides.
66 Diseases
Some diseases abound in the Canberra climate, mainly during the spring, summer and autumn seasons. Diseases can be dormant during the cooler months, or they produce ‘resting5 spores which germinate when conditions favour their develop ment. Our dry summers are not good for the spread of many fungal diseases, but as supplementary watering is usually carried out during these dry spells, they can be a problem, particularly the soil-borne fungal diseases. In many cases it is extremely difficult, even for experienced plant pathologists, to determine what disease may be affecting a plant. Some disease symptoms appear very similar to one another and, indeed, many bacterial and viral diseases, and their effect on Australian plants, are very poorly known and catalogued.
W hat is Disease? Plant disease can be defined as anv divergence from the normal functioning processes of a plant that results in a lack.of vigour. It is usually caused by the presence either on or in the plant of an irritating organism, or, physiological diseases, by environ mental or nutritional factors.
Types of Diseases Five main types of disease affect plants. 1. Fungal Diseases: These are the main causes of plant disease and all plants are open to attack by one or many species of fungal contaminants. Fungi depend on food that is already manufactured for their assimilation; they do not have the capacity to manufacture food for themselves. When this food is obtained from the living tissue of other plants they are known as parasites. Fungi do varying amounts of damage, depending upon the severity of the attack. All parts of the plant, both above and below ground, can be affected. Some fungal diseases can be very hard to control once established on their host. By the time a fungal attack is evident on the plant the pathogen will be already well established inside the tissue of the plant. Most fungi have complicated life cycles and may have more
67 than one host species nearby and thus may be hard to eradicate. They produce spores very profusely and certain spores are able to lie dormant for many years during adverse conditions. As conditions become more favourable the spores germinate and reinfestation takes place. Fungal diseases are of many types: leaf spots, root rots, collar rots, mildews, rusts and wood rots are all examples. 2. Bacterial Diseases: Very little is known of these species and their effects on Australian plants. The commonest symptoms are leaf spotting, decay in stem's, exudations leaking from the affected plant, certain root rots, some galls and wilting. One of the commonest symptoms appears' to be ooze or slime produced in any affected parts. Bacterial diseases are most commonly passed from plant to plant by the handling or cutting of diseased plants or by insect transmission. These diseases can be carried over winter in infected plant material or soils. The only efficient method of control is to remove infected material and to burn it. Crown gall is caused by a bacterial agent. It causes the crown of the plant to develop abnormally and this results in a loss of vigour and ultimate death of the plant. The only remedy is to remove and dispose of the affected plant. 3. Viral Diseases: Once again very little is known about viral diseases that affect Australian plants. Viral diseases live and multiply inside the cells of the host species. Viruses quite often do not kill their hosts but usually cause effects such as stunting or malformation of foliage, flowers or fruits. Viral diseases can be spread by propagating from affected plants, including in some cases through seed, and by insect vectors. 4. Nematodes: These are parasites that attach themselves to roots and in some cases the foliage of plants and thus reduce plant vigour. They are not of any serious consequence in Canberra. They appear to be more detrimental in warmer climates with lighter soils. If nematodes are a problem some species can be controlled by an application of Metasystox. 5. Physiological Disease: These diseases can be caused by one or a combination of many environmental factors. Cold, heat, drought, too much moisture, nutrient deficiency or excess, or a combination of the above factors can lead to plant illness or death. Deficiencies are discussed in the chapter on follow up maintenance. Physical problems caused by any of the other factors can be remedied by good siting of plants and by keeping a close watch on them at intervals during the year. Fungal diseases, then, are the worst and most common cause of disease
68 of plants in Canberra. Following is a quick resume of the more common fungal diseases and their controls. a. Fungal Leaf Spots: Fungal leaf spots are relatively common and affect a wide cross-section of Australian and exotic species. Most are not detrimental in any way. They usually appear as dark brown or black spots or blotches on the foliage and sometimes on stems. Hakea petiolaris is one species that is severely affected at times by a leaf spot fungus in Canberra. The whole shrub can appear black due to the infestation. Control of leaf spot can be effected by spraying with various fungicides such as Thiram, Captan, Maneb, Benlate, Phaltan and copper oxychloride. If control is not achieved with one fungicide, spray alternately with others as some leaf spots are resistant to some sprays. Alternating sprays also means that fungal diseases cannot gradually build up resistance as in spraying with one type of chemical control. Spraying with another chemical while the disease is in a weakened condition will usually exterminate it. However, most leaf spot infestations are not serious and control is not usually warranted. b. Mildews: Mildews are only occasionally found and these are usually stimulated by warm temperatures and humidity. As extended periods of high humidity are relatively uncommon here, mildews are not a serious problem with most Australian plants, though they are with various introduced fruit crops, some of which are particularly susceptible. They occur more commonly on Australian plants while in a nursery or in glasshouses, where the atmosphere is more humid. As mildews can be very detrimental to young or soft plants, and as they spread rapidly, outbreaks should be controlled immediately they are noticed. Control can be effected by spraying with Benlate, Maneb, Phalton, Captan or Zineb. Certain others are also suitable. As for leaf spot control, alternation of the chemicals can be very beneficial. c. Rusts: These are perhaps more common than mildews. They are usually found on plants with succulent, fleshy tissue and appear in the form of small, raised orange to yellow or brown spots dotted along stems or under leaves. Some species of rusts have a w ide host range and for this reason can be hard to control as rapid reinfestation takes place. Some species of the Asteraceae (Daisy) Family are particularly susceptible and rusts are not unknown on terrestrial orchids in cultivation, especially the genus Thelymitra (Sun orchids). Rusts rapidly diminish a plant’s vigour and it is usually because of the affected plant’s lack of health that the infestation may first be noticed. As the
69 damage by rusts can be so drastic and their spread so rapid, immediate control measures should be undertaken. Some species of rust can be very hard to control by chemical means and there may be no alternative other than to destroy the affected plant. Some sprays that may be effective on some species of rust are Zineb, Thiram, Captan or Maneb. d. Wood Rots: Wood rots are usually found in m ore mature plants. Fungal contamination enters the true wood and begins to decompose it. The First signs noticed are the fruiting bodies of the fungus that force their way through the living tissue and develop externally on the affected plant. By the time that fruiting bodies are formed the fungus is well established in the plant. Wood rots are extremely hard, costly and usually impossible to control. With large trees fairly major tree surgery work can be undertaken by cutting out the rot and treating the exposed tissue with a fungicide such as Terrazole. Benlate or copper oxychloride. The wound is then left open to dry out.
This tree has had major tree surgery work performed on it. It was suffering from woodrot. The woodrot has been cut out and the tree bolted in certain spots. Once dried out it will be fdled with a suitable fdling agent.
70 When dried the cavity is filled with a suitable solid material. Some materials used for this filling work are concrete, cork materials, vermiculite and cement, bituminous fillers mixed with hardwood sawdust or vermiculite. This will give the tree a chance to recover. Once wood rot has begun it is practically impossible to stop. The main danger of wood rot is not damage to the vigour of the plant as it only affects the true wood, but it makes the plant structurally unsound. Any work carried out on affected plants is only a check to the rot, and may slow the rot down for very many years, but it is not a solution to the problem. e. Root rot: Phytophthora cinnamomi (P.C.) is the most common cause of root rot in Canberra and many other parts of Australia. It has been responsible for the destruction of over 70,000 hectares o fjarrah forest in Western Australia as well as many other major outbreaks throughout Australia. It is also a major cause for concern with many commercial fruit crops in Australia. P.C. destroys the fine root hairs and rootlets of susceptible plants. These organs absorb the water and nutrients into the plant. The symptoms of attack can vary from species to species. The first symptom is usually a yellowing of leaves and a wilting of the topmost growth. This gradually spreads to a large section of or the whole of the plant. P.C. needs warm temperatures and is usually associated with moisture before spread or symptoms are noticed. The major activity of this disease is therefore confined to the late spring through to early autumn. The problem can be accentuated during the summer months. Supplementary watering applied to the garden during warm weather can add the only factor that may be missing during this time - moisture. Frequent light waterings which do not penetrate can stimulate the activity of dormant spores that are found in the top 7-10 cm of soil. They rapidly germinate and as they are water mobile are able to spread, especially down slopes, rapidly. Besides warm temperatures and soil moisture favouring P.C., heavy soils do not help. The worst soils are clay pan areas. Clay pans or heavy soils generally prevent the formation of deep root systems. The plants form surface root systems. P.C. can become attached to the plant with the resultant root damage. During dry spells heavy soils can also become verv drv and, together with the dryness surface rooting and damaged root systems, the plant readily succumbs. It usually results in a very quick decline, usually one to two days, but some plants can suffer from this disease for their whole life span.
71 There is no certain way in which to control P.C. There are a number of soil fungicides which can be used as soil drenches but they act more as fungistats than fungicides, checking the activity, not halting it. The best methods to control P.C. are: i. To provide well drained beds. Inclusion of well drained mediums such as river sand enable water to quickly move away from the root zone to deeper depths of the soil where P.C. activity is at a minimum. ii. To incorporate plenty of organic matter into the bed before planting. This stimulates the activity of useful soil micro organisms and in turn this appears to hold P.C. in check. iii. To be suspect of unthrifty plants when planting. Be sure to purchase plants from reputable sources. Plants should be grown in healthy conditions right from the start of life. Potting and seed or cutting mixes should be very clean at all stages, and not all growers of plants are particular about this factor. Do not introduce the disease to your garden if you have not already got it. iv. Apply light, general purpose fertiliser dressings. v. The use of soil fungicides. If a plant is suffering from the symptoms of root rot then there is basically only one action to take. The plant should be severely pruned back so as to reduce the am ount of transpiration from the foliage. The soil should then be treated with one of the soil fungicides. This may enable the plant to recover. If the outbreak is serious then resistant clones or species may have to be planted. Some species show a great resilience to this disease and can be satisfactorily grown where P.C. occurs. Armillaria Root Rot: This disease is caused by Armillaria mellea. It is found more commonly in light soils but is present in Canberra. It attacks the roots of plants and the symptoms appear similar to Phytophthora cinnamomi. There is little control that can be carried out in the home garden other than following the guidelines for controlling P.C. If plants succumb to this disease it is essential to remove the stump from the bed before replanting. Any debris should be disposed of by burning. Collar rot: This rot is caused by P.C. or by a closely related species of Phytophthora. The plant gradually becomes ringbarked around the collar. Control is the same as for P. cinnamomi. To avoid collar rot, do not build up mulch or soil around the collar of the plant.
72 Some Common Fungicides and What They Control Copper and sulphur sprays were commonly used in past years but they are now being replaced by more efficient fungicidal sprays, though some have been around for many years. These are the ones I will mainly deal with.
Fungicide C ontrol T.M.T.D. Available as Thiram Lantox and others. This is a fungicide helpful in controlling many rusts, downy mildews, mildews, and leaf spots and can also be used as a soil fungicide. Dexon Used as a soil fungicide to control Phytophthora and Pythium. It can be used also in soil mixes. Captan Leaf spots and moulds. Zineb Downy mildew, leaf spots, rusts, leaf moulds. Karathane Powdery mildew. Phaltan Powdery mildew, leaf spots. Maneb Leaf spots, downy mildew, rusts. Benlate A systemic fungicide used against a wide range of fungal diseases particularly leaf spots, rots and mildews. With plant diseases, at all times prevention is better than cure. Always observe strict cleanliness around the garden. Burn or permanently dispose of any diseased plant material. When diseased plants are noticed remedy the situation straight away by spraying, pruning or removing the affected plant. More importantly, whenever using fungicides follow the same basic set of rules as applied to the use of herbicides.
73 Australian Plants for Pond Use
There are a number of Australian plants that are highly suitable for growing in our climate. Unfortunately many of these are not freely available to date. I will mention these species as I feel the only way to get a larger variety of plants available is to get the public to ask local nurserymen for them. This way they may be stocked before too long. Water plants are found growing in varying locations in ponds, and can be divided into various categories for simplification. Oxygenators are species that are totally submerged. These species help to aerate the water and keep it clear. They can be free floating or rooted to the bottom, e.g. Vallisnena spiralis (Eelweed). Floating plants are found on the surface of the water but usually have root systems that hang down into the water, sometimes for considerable depths, e.g. Azolla filiculoides (Water Fern). Some species are rooted in the bottom but emerge to the surface and flowering, etc. is carried on above the water surface. In these species the form of the plant below the water surface can be quite different from the emergent part of the plant, e.g. Myriophyllum spp. (Water Milfoil). Fringing species are species that grow around the edges of the pond. Depending on the pond level fluctuations, they can at times be immersed and at other times be true bank dwellers, e.g. many sedges and rushes. Following is a list of aquatic and semi-aquatic species that are suitable for growing in Canberra conditions. Phragmites australis (Common Reed) is a very vigorous perennial species that grows to 2m high and can grow higher in favourable situations. It has strong rhizomatous growth and will have to be divided annually. It is unsuitable for small ponds. The (lower heads are large plumes and are white as they turn to seed. It is reasonably common along the banks of creeks or rivers in the local district. Lythrum salicaria (Purple Loosestrife) is a perennial herb that dies down during the cooler months. It grows to about 2.5m tall and is topped by long spikes of pinkv-purple flowers. L. salicaria will grow in moist soils as well as in a fully aquatic
74 situation. Cut back to ground level when it dies back in autum n the plant will reshoot the next spring. It is an excellent and colourful plant for pool fringes. This species grows easily from cuttings placed in water. Philydrum lanuginosum (Frogmouth) is a succulent-leaved per ennial herb in aquatic and semi-aquatic situations. Philydrum grows to approximately lm tall. The flowers form a long spike, are yellow in colour and are some 2 to 3 cm across. It is readily divided to form new plants and also grows very readily from seed, which is formed in profusion. Myriophyllum spp. There are a number of species of Water Milfoils suitable for growing in Canberra. The more commonly grown species are M. verrucosum, M. propinquum and M. pedunculatum. These are usually fully aquatic plants but they also grow well on the wet fringes of ponds. The flowers are relatively insignificant and are found in the leaf axils of the emergent stems. These plants are mainly grown for their bright green foliage, which consists of underwater leaves and emergent leaves which are quite different in form, the underwater leaves being large and dissected or lobed and the emergent leaves crow'ded in whorls on the stem and usually entire in shape. To propagate these species division of the rootstock is the easiest method. Potamogeton tricarinatus. Floating Pondweed is common in dams and creeks throughout Australia. It is another species grown more for its foliage than its flowers. The leaves are oblong in shape and float on the surface of the water, though some underwater leaves are also formed. Floating Pondweed is rooted into soil and is propagated by division of the rootstock. There are other species of Potamogeton but P. tricarinatus is the one most commonly grown. Water needs to be at least 15 cm deep for satisfactory growth. Nymphoides spp. These are fully aquatic herbs with reniform (kidney-shaped) leaves. They are usually known as Fringed Waterlilies. A number of species are grown in cultivation but N. geminatum and N. crenatum are the most reliable in Canberra. They are rooted into bottom mud and need water at least 30 cm deep for best growth. Flowers are usually yellow and some 4 cm across and held on a short stem above the water. Flowers are not long-lived but are reasonably abundant. The foliage is also a very attractive feature of this species. Propagation can be carried out by division of the rootstock and a natural means of regeneration occurs where a leaf will develop roots underneath the water. The leaf is simply detached from the plant, potted up
75 and then grown on to form a new plant. Ottelia ovalifolia is a particularly attractive species and very reliable in cultivation. It is a bottom-rooted species with floating leaves. Flowers are white to yellow tinged and are 6-7 cm across. It needs water 30 cm deep at least for best growth. It grows from a perennial rootstock and is best propagated by division. Azolla spp. Azolla is a genus of water term. Azollafiliculoides is the one most commonly grown in Canberra. It is a free-floating species usually found on still or calm ponds. It can usually be recognised as it is a reddish colour and is found in large colonies. A. filiculoides can actually become a weed in good conditions and may need constant thinning out, so propagation is not a problem. Water should be at least 5 cm deep for satisfactory growth. Marsilea spp. There are a number of species of Marsilea, commonly known as the Nardoos. They grow either as aquatics, where they perform best, or in very wet mud fringing ponds. Marsilea have long creeping rhizomes and, as for other fern species, can be propagated by separation of the rhizomes and potting the separate pieces to form new plants. The leaflets are in fours and resemble a four-leafed clover. Marsilea are best grown in water from 10 to 30 cm deep. The most common species in cultivation is Marsilea drummondii. Villarsia spp. Villarsia are very desirable additions to any water garden. The commonest species grown are V. exaltata and V. reniformis. They are perennial herbs that can be aquatic or semi- aquatic. The best example of Villarsia that I have seen was growing in heavy, wet soil on the fringes of water. They usually grow to 30 cm tall but can get larger. If grown in water it should not be more than 10 to 15 cm deep. Villarsia can be propagated readily by rootstock division or from seed. If growing from seed it can be growm in a normal fashion and when potted can then be introduced to water. Ranunculus spp. There are a number of species of Buttercups that grow either as aquatics or semi-aquatics or simply in very moist soil. These plants have very glossy yellow flowers in most instances. Flower size varies from species to species but an average size would be from 1 to 2 cm across. Flowering is usually quite prolific and extended over a long season. Recommended species for Canberra are R. lappaceus, R. rivularis, R. inundatus, R. collinus, R. pinpinellifolius, R. scapiger and R. sessiliflorus. If conditions are good ranunculus will self-sow themselves, sometimes considerable distances from the parent
76 plant. They do not become weeds as undesired plants are easily removed. Typha domingensis. The Bulrush or Cum bungi will be familiar to most people. It can be a useful addition to larger ponds, but must be kept confined as it can be particularly vigorous in growth and invasive. Bulrush grows to a large size, reaching some 2 to 2.5 m in height. Propagation is best carried out by division of the rhizome. There are many more species that can be associated with water, but not necessarily as aquatic plants. These plants need moist soils and can be grown on pond fringes or in close vicinity to a water feature. They include Blechnum cartilagineum, B. nudum, B. wattsii, B. pennamarina, B. minus, Polystichum proliferum, Dicksonia antarctica, and Hypolepis regulosa as examples of ferns. Other plants are Bulbine bulbosa, Mazus pumilio, Mentha australis, rushes and sedges generally, Viola hederacea, Pratia pedunculata, P. purpurescens, Hydrocotyle tripartita, Cotula alpina, Dianella tasmanica, Phyla nodiflora, Neopaxia australasica, Pelargonium australe, Scleranthus biflorus, Veronica gracilis, V. notabilis, Australina pusilla, and many Lomandras, all small plants for close to pool planting. Larger shrubs are also available to plant in moist soils but these are dealt with in the chapter on plants for specific areas. Aquatic and semi-aquatic plants are normally fairly gross feeders. When mixing mediums in which to grow them they need to be reasonably rich in nutrients. A good general guide for a mix is: 2 to 3 parts of a good loam 1 part leaf mould or compost 1 part well-rotted manure. Water plants can grow prolifically and many species may need dividing once a year. At the very minimum, they will need dividing at least once every two years. So it is far more convenient to grow aquatics in pots, which are easily removed from the pool when dividing is necessary. If plants are not divided when needed there will be drastic deterioration in flowering and general plant vigour. Nutrients, leached fairly readily due to submersion in water, will be another reason for reasonably regular repotting. Wet the pots thoroughly before submerging and then lower them gently into the pool. Due to the texture of the mix, sediments will be stirred up from the mix as the air bubbles leave it. This can be minimised by the addition to the top of the pot of a layer of fine river gravel some
77 2-3 cm thick. One caution on garden pools. Extreme care must be taken to protect young children - your own or someone else’s. Constant supervision is rarely possible, so the pool needs to be child- proofed, either by a mesh over the pond or some form of barricade around it. A pool depth of only 3-5 cm is sufficient to drown a small child.
78 Indoor Plants
The indoor plant market is booming all over the world and Australia is no exception. The main reason for this appears to be the increased amount of townhouse and multistorey development that is taking place at present. People generally seem to enjoy having plants around them and when they do not have a garden they turn to indoor plants to provide their enjoyment. Some species of Australian plants have been in cultivation as indoor plants for many years now. Examples of these are Schejjlera actinophylla (Umbrella Tree), Grevillea robusta (Silky Oak), and Cissus antarctica (Kangaroo Vine) and many of our palm species such as Archontophoenix cunninghamiana, A. alex- andrae and Howea forsterana Kentia Palm. Even though these plants are well known, our tropical and rainforest flora is an untapped source of potential indoor plants. Some keen growers are trying many of these species in Canberra and, indeed, many are proving to be excellent for indoor use. I feel it is unnecessary for me to go into the details of the culture of indoor plants as so much literature is already available on this topic. Rather, I will give a list of species suitable for use indoors and mention in the few comments that follow' any factor that should be watched. As I mentioned in the chapter on w'ater features, many of these plants may not be readily available for purchase, but only through public demand will they ever be stocked. Some may be available through specialist organisations such as the Society for Growing Australian Plants or from specialist growers. Adiantum aethiopicum (Common Maidenhair Fern). This species has been in cultivation for many years. In nature it is more usually found on creek banks and in shady situations and seems to need simulation of these conditions when grown indoors. It seems to appreciate a moist atmosphere and very quickly succumbs if growai in a dry atmosphere. Avoid placing the plant where it wäll receive too much sun through glass as it may become sunburnt. Other species of Adiantum are also suitable for indoor use. Some of these Are Adiantum diaphanurn (Filmy Maidenhair), A. hispidulum (Rough Maidenhair), and A.
79 formosum (Giant Maidenhair). All these species require the same conditions. Propagation is normally by division of the rhizome or by spores. Agathis robusta (Kauri Pine). This is a very hardy indoor species grown for its large lanceolate leaves. It is hardy in just about any situation indoors. A. robusta may be hard to obtain as far south as Canberra but fresh seed germinates readily. As with all pines, growth after germination can be fairly slow but this extends its life as an indoor plant. It can also be propagated by aerial layering. Araucaria bidwillii (Bunya Pine). This species, together with A. heterophylla (Norfolk Island Pine) and A. cunninghamii (Hoop Pine), are all very hardy indoor plants, A. bidwillii is able to withstand our winter frosts and could be planted out when it becomes too big for the house. All three species relish a reasonable amount of light or their growth becomes very flaccid or soft. They can be grown from fresh seed or by cuttings or aerial layers. They are sometimes available in Canberra as indoor plants. Archontophoenix alexandrae (Alexandra Palm) and A. cunninghamiana (Bangalow Palm) are both excellent indoor plants. They are readily available, one of the main advantages of palms generally being that they do not mind being severely pot bound as long as they receive water and nutrients regularly. This also enables them to be kept in a small pot for a very long time. They are very readily grown from seed, with the seed sometimes germinating before it is sown as long as it is kept moist. Fresh seed should be used and a good method to germinate it is to put a layer of moist peat into a plastic bag, lay the seed on top of the peat and seal it off to keep humidity. Seedlings when germinated are potted in the usual manner. Archontophoenix seem readily adaptable to both light and darker situations. They have very large pinnate leaves. Boea hygroscopica. This species is very closely related to the introduced African violet (Saintpaulia spp.). It requires basically the same culture as the African violet. Boea has purple to blue flowers on a long stem. 11 shows great potential especially when a little more breeding work to shorten the flower stem and increase the flower size has been done. It is grown successfully by leaf cuttings in the same fashion as for Saintpaulia. Brachychiton acerifolium (Illawarra Flame Tree). Is gradually becoming more used indoors. It is grown for its very attractive, large, lobed leaves. It can be relatively fast growing indoors. It should not be placed directly in front of windows as new growth
80 can be burnt by strong sunlight. It is highly unlikely to flower indoors. Propagation is by seed, which germinates slowly and must be sown when fresh. Cuttings and aerial layers can also be used. There are a num ber of other Brachychitons that are suitable for indoor use. These include B. populneum (Kurrajong), B. rupestre (Queensland Bottle Tree) and B. discolor (Scrub Bottle Tree). All are grown for their foliage shapes. Culture for all of them when indoors is basically the same, B. discolor requiring more water than the others. B. discolor is also very fast growing and will outgrow the house after about four years. Cissus antarctica (Kangaroo Vine). C. antarctica is a very widely grown indoor species in Europe and has been so for many years. It has a reasonably vigorous climbing habit and prefers a shady spot. This species requires either mesh or strings to climb on. It can be grown from seed or cuttings. Two other species are currently showing potential as indoor plants: C. hypoglauca (Water Vine) and C. repens. They are also climbers.
Cissus antarctica
81 Cissus repens is especially attractive: its juvenile leaves are mottled and, when more mature, the leaves have a strong purple colour on the back. Cordyline spp. A number of cordylines are very suitable as indoor plants. These are C. stricta, C. petiolaris and C. fruticosa. They are usually single stemmed shrubs with long strap like leaves. Most species have white to purple flowers followed by berry-like fruits. Cordylines are grown very readily from fresh seed. They will flower indoors and are very hardy species. They appear to be fairly gross feeders and prefer a rich potting mix. Dicksonia antarctica (Soft Tree Fern). Young tree ferns make excellent indoor plants provided the atmosphere is not too dry. They also need watering a little more often than many other indoor plants. Large plants can be kept confined to small containers providing water is kept up to them. When too large for indoors D. antarctica can be planted outside in a sheltered position. Ficus spp. These are the native figs and most species grow into extremely large trees in their natural habitats. A number of species have proved very suitable for indoor use. Some of these are F. rubiginosa (Port Jackson Fig), F. platypoda, F. macrophylla (Moreton Bay Fig) and F. pleurocarpa. The last species, F. pleurocarpa, resembles closely the exoticF. elastica (India Rubber Plant) and culture of all native fig species is the same as for F. elastica. Ficus are readily propagated from cuttings or aerial layering. Grevillea robusta (Silky Oak). This species has been well known as an indoor plant in Europe and America for many years. It is a tall rainforest tree in its natural habitat. It is grown for its very attractive, deeply divided grey-green leaves. It needs reasonably good light to perform satisfactorily indoors. G. robusta can also be grown out of doors in Canberra, attaining a height of some 15 to 16m, so when it is too tall for the house it can be planted into the garden. Grevillea robusta can be grown from seed or cuttings, though cuttings can be slow to strike. Hoya spp. Australia has a number ofHoya spp. They are a genus of rainforest or wet forest twining plants. H. australis is the species most commonly grown, though two more species, H. nicholsonie and FI. macgillvrayii show great promise. Hoyas have ovate leaves and the flowers form in umbels. //. australis and //. nicholsonie have white flowers while//, macgillvrayii has verv large umbels of red flowers. The flowers are scented and most Hoyas will flower well indoors. Propagation is extremely easy from cuttings.
82 Nepholepis spp. (Fishbone Ferns). Both N. exaltata and N. cordifolia are hardy indoor ferns. They are adaptable to well lit or slightly darker situations but should never be placed in draughts or where they receive strong sunlight through glass. Propagation of Nepholepis is normally by division.
Nephrolepis exalta Pittosporum spp. P. undulatum and P. rhombofolium 1 have seen used as indoor plants. They appear to require a reasonable amount of light to retain a good shape. If the position they are growing in is too dark, they drop the older leaves, leaving a very sparse plant. Both species are grown for their glossy leaves. They will grow satisfactorily outdoors in Canberra if planted in a sheltered position. New growth can be tipped by frost. Pittosporum can be grown from cuttings or fresh seed. Schefßera actinophylla (Umbrella Tree). Schefflera is well known as a house plant throughout the world and its reliability assures its continued use in future years. It is so well known no comments
83 should be necessary other than to say it grows well from fresh seed. A new species of Schefflera as yet unnamed has been found in tropical Queensland. It has hairier leaves than S. actinophylla and is showing promise as an indoor plant in Brisbane. Stenocarpos sinuatus (Firewheel Tree). Stenocarpos has quite large lobed leaves and grows well in a well lit position indoors. It dislikes sun through glass and needs to be well watered for optimum growth. It grows best from fresh seed although it will strike from cuttings. Melastoma polyanthum (Pink Lasiandra). This is an Australian species that closely resembles Tibouchina semidecandra (lasiandra) introduced from Brazil and widely grown as an ornamental in warmer climates. M. polyanthum has two forms, one large leaved and one small leaved. The small leaved form is better as an indoor plant. M. polyanthum has to be regularly tip pruned to keep it at its best. It will flower indoors though flowering is irregular and spasmodic. The flowers are pink to mauve and up to 5cm across though more usually 3cm. It is very readily propagated from cuttings. Toona australis (Red Cedar) This is a tall tree in its natural habitat and was nearly exterminated last century due to the value of its timber. It is grown for its large compound leaves and needs plenty of light when grown indoors. Strong sunlight through glass has been known to burn its foliage. Toona appreciates good and regular waterings and it can be grown from cuttings or fresh seed. Plectranthus spp. Various species of Plectranthus are suitable for indoor use. I have seen P. paruiflorus, P. graveolens and P. argentatus used indoors. They need plenty of light and regular tip pruning to keep them shapely. They will flower indoors, the flowers varying from white to bluish-purple tones. They are very readily struck by cuttings. Asplenium spp. Two species of Asplenium are extremely good indoor plants, A. nidus and A. australasicum are two very similar species with the vernacular name of Birds Nest Fern. They require a reasonably hum id atmosphere and will grow well in relatively dark situations. Most commercial outlets stock these species. A. simplicifrons is another closely related species with much narrower strap-like leaves. This species is also showing potential for use indoors. Peperomia tetraphylla. Most people will be familiar with P. magnoliaefolia, an exotic species commonly sold as an indoor plant. P. tetraphylla is an Australian species which normally
84 grows as an epiphyte or lithophyte in or near rainforests on the east coast. It has attractive reddish stems and glossy ovate leaves in whorls around the stent. It needs a fairly porous organic mix in a reasonably well lit situation for optim um growth. It is very readily grown from cuttings. Tip pruning is a definite advantage to keep it more compact. Blechnum nudum (Common Fishbone Fern). B. nudum grows well as an indoor plant even in a relatively dry atmosphere. Fronds should be removed as they die as this appears to stimulate the formation of new fronds. It will tolerate reasonably well lit situations and appreciates regular watering. B. nudum is usually available from commercial sources. Macrozamia communis. This is the Budawang which is seen commonly on the forest floor on the Clyde Mountain. It is an extremely hardy and reliable indoor plant but is very slow growing. It is grown from seed which is slow to germinate. The related genus Lepidozamia has also proved promising. Lomandra spp. L. longifolia and L multiflora are plants with long strap-shaped leaves. Flowers are formed in small spikes that develop at the base of the plant. The flowers are perfumed and cream to yellow in colour. Lomandras can be propagated by division or from seed. There are many other species that have great potential as indoor plants. Many of these are being grown experimentally at present and no doubt will become more readily available as they are proved reliable. A great many plants can also be used indoors for short periods of time. They can be grown in pots outdoors and brought indoors when they are in flower or fruit. Acacia, Correa, Boronia, Callistemon, and many species of monocots, particularly bulbs, are grown for this purpose. Crinum and Calostemma are two very good bulbous species to use. A large number of bulbs can be grown satisfactorily in a small pot and such a massed display can look very spectacular. More species are being experimented with for use of Bonsai subjects. Many genera such as Banksia, Eucalyptus, Callitris, Podocarpus and Pisonia have shown compatibility to this method of plant culture. Bonsai are usually kept outdoors but can be brought indoors for short periods.
85 Suitable Plants
It is always very difficult to know how to prepare a chapter such as this. Following comments received from many people I have decided to prepare it in table form. In a book of this size I have not been able to include anywhere near the number of species that are suitable for growing in Canberra. I have based the list on species that have enough specimens scattered through Canberra to recommend them as suitable though this does not necessarily mean that they are fully reliable. More detailed descriptions of these plants are available in other literature and so they will not be dealt with here. The plants have been divided up into five main sections, prostrate to 0.5m tall 0.5 to 1.5m tall 1.5m to 3m tall 3m to 10m tall 10m and taller Comments such as whether the plant is an annual, screen plant or any other feature will be found in the extra comments column. The plants have been grouped only under a height category and are based on Canberra conditions. They may differ somewhat in other areas of Australia. Even in Canberra heights may differ depending upon the source of the clonal material of the plant and on the conditions where planted here. The tables are compiled so that they are a very quick reference for people less familiar with these species. Good drainage should be presumed unless otherwise stated.
86 _2 »C E 5 / C ^ D. a" £ .)X ^ *2 b !/j cb a £ / 2 -a 'S _>■ ri H .5 s 1 5 Q. o J & So J noist 1 1 C O DX -C a. ä .« 'a C S rt S£ > — -G 'S J P SL -P O- i ^ <3^ ^ 3 a- a- ? S g - g *? 'S) £ § bC fc = o bio > 3 flj ^ s £■■? O s = c 3 noist *2 _C IS 3 ‘5 3 Cu I ! s noist *—1 2 5- -B 'S 'S0 £ ■Hi i i I i ? i «3 < qn< X< £ «/ S § 87 )ist-drv V» 3 | J | = Si - £ C/5 C/5 £ - li £ < ~8 ^ Q y «Ü *- 3 5. .3 *s w c r- lO h c ^ £ £ I ets ^ ^ -9 ^ ^ noist d 'S _C I •75 _o .£ C ^ - J 1 O be - p is c 03 £ O ct § o a j j 3 noist 75 •3 ■g ~p s. £ £ = 3 3 V ■O £ J Qj CQ 03 “(Tj s ~G &0 73 '5 rb £ £ •c CL > " § ’ bo b e 'S % s S ' a, C/5 2 z I - sC/5 I—F C/5 l C/5 i U p / U> c/5 C S Q 1/ o j: .t: " -G _c u S- _c v 3 S £ j: "C £ C Qj O C Oo > . bezz zz zz C O O ««I G G Qj V U, u >, > . > •£■3 -O-c •=-3 T3-r £ S 5 7 7 a (u 3 w a. Ql qS Ss Ss 'A C/5 7 C/5 C/5 to C/5 C/5 •c £ £ ”S - - > ’o ’o ‘o ’5 o ‘o ’o ’o '5 : : ä = | I £ £ C/5 C/5 ^ <7! c o r -c 03 _ 5 I 1 X £ £ 5 2 ; C/5 • £ l ■=c2^ . i cZ >■. tL ■ — - f 3 3 i , , • -* ’7" —* r- r- £ 3 O 5 3-S 3 x S "7 3 3 r - C/5 .£ 3 *■" —* * - c/5 S3 £ C § s ü i So £ I >, 3 j~ -= l i l t I I- - s i 3 c o £ 15 £ Z 3 = Ü C E cz 2 03tr: 3 • - ii Hit- cc cc S SC CC CC CQ SoCC 03 CO CC 02 88 Qj bC -Z fc £' ES ~ b £ C c ^ f i fc fc C Jt re O 2 °O IS £ u "H. U 5J 1 r-> ü ; ^ 0> ^ • a 1 /5 U - I x bL O c / 5 O -5 "S s s s s r c 3 I 8 * y ^3 ^r l O ,rS fee 3 S> JS £ .2 "s J* -o j* "2 8 2 § * § 8 be C be u be u Cd 3 13 CL cd CL I 1 I C/5 I C/5 Q S s i ; " CL e r £ e g C/5 £ 3 £ 5c 2 i." a* 5 c cd 3 ee 5/5 £ ^ CL 1 lo 1' cd C/5 Q , ^ ’ 5> < o c / 5 c c c c . c t c r : > u 1 (L I S 2 S3 r* *b r" ^ r- w r-* i ± c g 3 I sJ2 3 3 3 T3-§ -O7? 3 * 2* S*JÜ ? LT, cd cd cd cd cd cd cd cd 5n J b JL JJ j y JL ’5 JJ . 2 " 5 5 £ ■ £ .2 .2 .2 "8 5 1 2 3 CL-c w 2 2 2 L cL o _ c a 2 § • cd ES e t ~ - S c c - - g TC - c ■3 3 | cd ’S cd t t C £ OJ i O ~ c _ e t * *- cd «/> 3 2 *—' <—■ ^ r - 2 5 | i ge 2 £ & 5 £ O- 2 ES > u _o^ c * 3 .2 bce^ | ! £ 5 ’S - er: f - S 2 2 ^ ~ o -* o fegE 2 ■2 a-ES "C _ C r - £ 2 " 2 E E .2 “ c •i S - f l | 3 2 c £ 5 £ s t -C -3 3 J et er c o o s s ; : £ 5 .2 o S • u u u u u U U Q Q a "5c Q Q cl Q 89 Species Spread Situation Ex- Flower Flower Extra Commei m posure Colour Season <-2 £ - C3 L- 3 & "3 t o ‘o ‘o s (Tj rs J3 ä * "3 - a SI u E , s a, § 8 CS o >•3 C c3 CL £ O * On C/5 C/5 C/5 c J i . g E E 3 ß a a fa be > 2 §1 : § 3 3 .£ C/5 3 brevirolia 1 £ a o ■a & ü n — < G. biternata c c 2 - 0 O • r- M 1 8 " 2 fb .2 i < O C3 2 ^ 2 -S .- & ö - _Q 2 *- 3 3 L l c r t CL CL t r fa- c — — S—i > • *J '• >> J2 c CLCL 2 11§*« I i i a ^ >—> rH nrt 2 u G. confertifo be be J3 t J D J L L O L JDJU o T3-o u u 0 > O > L 90 G. ilicifolia* 2 "0 o 3 3 "C -3 -3 -o ! C 33 JC 3 3! . S e S ..% N cOCN (N ^ a S E $ 6 H 3 n3 O O ^3 - - s- u J- i- !« CL CL a e e be be fa 2 u u QJ u u C G. la u rifo lia ” sp * # 41 j v T G. ‘ Royal M; su - - ■- ~ Si C 2 o3 IIs l G. thelemani A pr.-O a S * J * J l s ■ £ ' £ 3 U O o _ u r* ’o o C/5 00 G. trinervis* sp a - _o CO a e fa l c/5 OJ <3J l c « (b r« 2 Ü * £ flj n3 E Goodenia hede sp-sr JU _o -a p wo o 00 L L CL >, cl > G. hederacea •f alpestris C/5 OJ Ö s 1 3 3 _o cd cd 3 g 0 'S 03 Q.’Dh <5 .3 s äs 1 0 .2 15 15 £' £' C c5 3 a, 13 S su su ** " > sp-a d sp-su sp-su sp-su sp-su sp-su £ . o _c B* = 3 < u 13 4 g -f X T) S X a. >. § >■ >. "I 3 E £ ’ c u ' o . c c ■ < u 3 3 ' £ "C C/5 C/5 ««'I i I s-± £ 2 'S0 3 >5 03 C/55 -= C/5 'S T O T>s O JU 0 3 03 C/5 - U C/5 E o 'S 3 CJ 2 c cd £ S £=2 -o 3 Sc 'So 5 X 3, _ O :3 ■11 I C cd _ o 5 3 Cj ■S 2 JU 91 Species Spread Situation Ex- Flower Flower Extra Commei m posure Colour Season ^ a _c -a ^ "O— _Q JtS äjj*3 ' ' I j j — r c c* c* r* *—• 3 3 3 cd cd cd jd 3 <£ .2 V 2 =£ 5 3 2 3 _3 3 2 3 5 •2 ■si , 1 g ^ g g 4,13 S5 —; 1 . c £ 3 d cd cd 2 S c /3 l Aug.-De jd 1-514? —> 5 C/55 C/5 £ c C /3 S£ 6| £ 3£ 3 §Lg,x g ^ C u ^ CL ^ ^ 2- G. f t I E 3 O ^ "O s 3 bJD ^ c/3C C o :§-S 5b ^ J J ’S ‘ i s i I jc 2 /3 2- ,.2 £E I 3 -3 ifitl U . O . 3 U . sp-su c- 2 .2 w-sp cj 3 2 sp-a 1 T3 3 3 13 TJ JU .2 be D 3 io 1 o £ 3 >. cd cd C/3 late sp h JU s Z *■0 £3 U c/3 £ o c /5 s u e s u e 13 s u U m r o c m a s s m a s s m a s s m a s s c dj a C b£ V nj fc ^ c l - 2 Ü Q-J )Q <3 s d - s n 5 S Om s n s n s p s p s p s p C/5 s u S 3 2 s p - a s p - a s p - s u o te s p - Z O SZ rU b l u e b l u e p i n k w h it e w h it e w h i t e v io le t v io le t y e l lo w p u r p l e y e l lo w p u r p l e p u r p l e y e l lo w o r a n g e bright pir ■ i - § L _C ^Islslsls ! i'll I! 11 I s|s| c/> ^’S^'S^’S^’S Sl-s s-s Si 'S .2 . 2 Qj D S tn o ’o 'o p s i 1 C/5 C/5 C^ ^ ^ E g S o 0 CL CL '5 'o '5 nj r-1 c C 2 -5 2 o o t C C P C " " r - s T3 t i 1 * flj b b 2: T3 "C L> - c "U .C O CO CO CJ 5 JU Si ~ I Si v S sc/5 C /5 1 1st C /5 S £ C/5 2 2 3 , S 3 & .OJ . L _C s s s z o s b ö £ CL CL CL CL CL CL o Cl 93 fc to £ M £ 2 Oh U CL g u. c/T Ü 3 S s 3 o to e d f r u its r o c k e r ie s _x O U u CL % I s p 2 ^ s p s p - a s p - a s p - a s p - a ° 2 s p - s u s p - s u t e s p - s u tu m L It Q JS 3 C3 -o ; i !U ■g 3 u I- s- oj 3 , > , ^ £ 3 "l ■f le le a p t- a p t- le a p t- >un s u n m Cd > i rn Cd < ■ Cd u n i - a d e -o JC •O 3 3 3 "O _c -o X) C -C "O L2 cd cd cd cd cd cd PC pC Cd Cd c/5 to cd rd « .2 .2 4, C o V Q ~a QJ ('S w> -O a; _ 8 £ lO ■a *Tj io —• —« a - '5 % *« '5 ■ 5 = J3 £ 2 2 1 - 8 3 c CL 3 2 jS 3 u c — 2 « c <2 £ 8 ~ I I £ -a 3 U°1 C fljcd • — 2flj SL §■§>§ 3 Sll-2 5^ x' ^ I i ? . = 1 15 ° ]§• . § C 8 ‘ Jill ll ill! cl cl o- Q- CL to 1 /1 1 S a - o ’o 'o I JL •c 5 / c " r L * /5 C CL < < - 9 — *—> *—> 0 - r " r C b r j n l ) / ; a /5 c w h it i l 3 1 .£ .2 C I& I f I I l l i 3 /5 C / o () / c) / ace/) e c a (/) c/) c/) (/) o c/) CL CL 5 = .1 J * 3 S S § .§ ^ S -S I 3 3 1 33 o'o =2 £ 5 2 5 0 s n u >> ) S) S) CL I £ 33 .3 ’5 s n u 3 > “ o ‘ O " Ö " c c u u V 5 r-> w L - , J- *L " Q — 33 O '6 ü o 1 u 3 o c 3 * 3 n 3 3 - '5 ' ID C CL 3 * 1 3 o /5 2 c 2 £ 5 o 2 3 - / c ^ c L J 3 3 ' - Z ' S < 1 ‘o CL j r 5—■ U S I S o H > 95 <& c/ 5 *L 3 3 'o 5 5 > Cdc^fdo 2 C O C/5 2 L < ’ w i d e 0 - 3 3 ’o £ .2 2 J (N > C CL 03 *L> C o t /5 o c Qj 1 3 3 3 3 'S 33 ts 13 OJ > > £ , > c a c/ 1 1 S - o 5 « o £ J Q 2 o 5 3 w i d e c /5 33 _£3 ’o % .9 2 B- J s e m i- s h a d e 32 Ü i J I 3 5 e b - £ o3 B> s u n 1 „ 5 1 -a ■£ C/5 s~ <3 S) S- bC PLANTS .5m - 1.5m Species Spread Situation Ex- Flower Flower Extra Commei m posure Colour Season *«, 3 = £ "O 111 I 111 < < ec < < < s- S - * 05 '• £ c c 5 = 5 C 3 CJ c u c * /3 C -a u j 'V 2 s 3 £ 4- « 1 /3 a o u u £' Q V (/> h O 3 Ü 5 *0 'S i IS ’£_ "O c: u u 3 cG 3 £ Ü 2 C/JC/54—>C/5C/3(/it/it/3(/)wTOTOC/}C/}(/3ü UC o a o G £ 11 t i l CD U < *5 i "O i—H <-g o * o 2 5^2 i g to S V o - i i i i c cj-c cj-c £ "O .2 o' o'o 'o '5 'o > ” -2 ‘o >o ~a T — G "C c c ° 2 m a n y I c Sc ibe a I § 'i4/ tD CL ^ j > . 5 (3 rt C- u be |1 t/5 >■* CL E. L- CL < |I C/5 * " 5 c be s - 5 r 5 c/> . § > ■ £ "E c/5 U u 7 Qj ^ 1/ T3 j I -O ^ tbe n s u n s u n t o s u ns e m i s h a d e s e m i s h a d e s e m i s h a d e s e m i s h a d e s e m i s h a d e t o s u n s h a d e s e m i s h a d e t o s u ns e m i s h a d e s e m i t o s u n 5 SI U IO JS U IO JS U JSIO SOU JSIO t o m e n o i s t n o i s t n o i s t j j o i s t n o i s t £' T3 in C O ^ ‘O >o oo __ 2 c C* ~0 S 'S 2 cd i-g Is % % 5 _o 1 2 ’5 rd £ 13 97 Species Spread Situation Ex- Flower Flower Extra Commei m posure Colour Season "O <% I 3 qj CL % J ° - £ -r C/5 JS C/5 °° TO 3 <—« £ !✓) 'S c be £ j C 3 9 qj /5 C CL £■ ^ £ 3 £ 2 ^ 5 > . Ö .2 Ö Ö .2 2 £ c * 2 * £ a. O a. E O $ Z V V 5 5 -C "C = 2 £ £ Z ^ Z Q •- CL C 2 'C 3 3 'C 2 CL•- C «3 W j3LiUj C 3 W W Q a £ 2 u 2 E £ o • s ' 6 £• >- § a 5 C/ 5 / < /5 C /5 C ^ ^ - & £ 3 3 3 3 CL £ /5 c ^ o asU ^ oj Nl-i % S I c p ^ * ^ 8 2 * S ^ IS J J o £ c £ * be >> ty -2 £ Ou . s s . JU 98 ^ q-> t 6 < a be 3 —1 3 -a IS -a ’o V) O N CS 5 . o o >. - ^ .3 6 5 C/5 C £ E /5 C 13 jd C 3 c _ I §i eo fe o ° 2 rt rt 2 ° < >-. £ 2 u L 2 = O £ o o ** E d _c «2 ”0 -a < o ' t s- 3 l a be 3 LD3 'S O _2= 32 ;s ”5 c j? a. £ ■3 o fr<§ 3 3 S i 3 feb fc s 2 3 , • 3 b b > . 2 3 c d < CL O h 3 3 3 a, o9? C/5 C/5 C/5 C/5 C/5 c/5 L w-sp 3 S o 3 Q . ilv-Ja *13 § 3 < "33 3 s - " 0 b e 'S 'S 1 s ■5 d "3 "3 v -3 O 3 « 0 3 3 ^ a =3 O 3 ^ * S - pink pink white white ■> _ * > , _ 3 cream ~a = 'a. mauve c 3 a - 3 3 pink to r I S >, a 'S. £ uns uns 3 5 -i -S § I 'i -s 3 3 ‘-1 1—' C/)C/iCOc/5C/5GTOc/) apt- le sun sun sun sun 5 2 Q j 0 / _ 3 3 t/5 !/) (/I _G *—• *-< _Q d ^ & • 2 ^ >, 03 O .2 03 " § . 2 ‘o ’o *o a c ~ 0 ~ C T 3 1 -a •3 9 . 9 2 a . a. cd ^ c - 3 6 ~0 03 n3 cd Cd » 0 1 0 * 0 1 c o LO — 1 1 CM CM CM cm —< 1.5 1.5 5 % 2 U ■SC* c* .2 J5 leg™ e|| O 3 % §1 2 -2 C/5 2 2 « 3 I 3 -3 fc; * S 5 8 g 2 X I 1 E .2 JN ig 2 83-5 3 3 ^ fa J >• £.te ffS-g 3 = "El 3 - 2 > . o E o 3 - c G. 3 3 ~ III o g | 8.3 8 S 3 3 -s p 3 O r2 2° • o 3 . . > § odd odd S S s 99 u w a C/3 fa J2 o (t a u fa a • £ c C fc 0 £ p o s u re j i 3 5 2 ^ c u u 8 c ^ ’0 e c beg 5 D SS £ sem i Jan . * | sh ad e : '0 0 C/5 a- Qj r; £ 2 £ T:v o ,2 or Tv:vc r 33 S 3 fj ^ j f 3 I S c 32 .-3 S'2 fc 3 f I 1 sem i- S § sh ad e c 1 s . | 5 c -5 / C/5 Q- C/5 - 3 fa 3 QJ cd sun c3 able : c s ' o 2 S c c -S ^ g J Ü QJ £ O S 10 S . JJU QJ . 2 a.® . .2 .2 * fa-» w O cd sun w hite == .2 -5 .2 sun m au v e =9 T5 Jj c/3 fa-, c 1 Qj a d a p t £ lite o r hi able -s ~Ö w n T3 cd C .2 u QJ O cd cd 2 § ä . S £ h a d ap t able § ' i O 'fa 33 1 ~0 —i G 3 2 c 0 * 2 sem i 2-2 shade U-. .2 u .2 £ £ .2 s H > o S - ‘n O •be I ’So .2 5 / c a, Wesi cd PLANTS 1.5m-3m Species Spread Situation Ex- Flower Flower Extra Comm m posure Colour Season o c •Ö §D _J -a o '5 -o 2 1 1 * * 2 N — (N V b0_O > r5 < < fr 2 o - r-1 r- fr 2 o o Ec E E un 3n 2 * 02 O r- O - 2 ~c v & C/3 O- 2 t rd rtf "«D J TJ ‘o 2 ' 1 •c *0 oi < Ä r f 3 O 1 C/5 2 'S 1 2 2 1C 2 4 4 4 -C _Q _C 0 3 S O S3"0 IS l (NOl CO (N & fr / C5 ^ O O C/5 C/5 Q-i O-i n < < < < bebe be ^ 2 ^ '2 2 2 '2 ^ 2 1ij^ j i 11 o • o >• o o t ctf ctf 0-. Q- 0-.~n i i u ti ii S fr c £ S £ 2 E 2 c 2 £ 2 2 S 5 _c I £ s’ 101 •C Q- rtf C/3 2 2 ^ — Qj CO CO (N g'i bp < < < 5 o /5 c > o. 0/ . . H H . >.2 . e 0/ w o c c S c c S c c 2 S J“23 £■2 2 2 £■2 - ! ■ ! » £ i s - / *—> C/3 L- « £ tfa i i C/5 !_• a. CTJ >■=: £ t/5 >. a -O -a rtf ct 3 ■c on I 1—> "C 2 ;c a. 2 J < c i) u Q- b ^ * ^ E Q. n 2 1 -C '2 b - -Q -a 3 "b 5 T S§ .2 S bjci v CQ ^ . S y j - g V £ .22 O " v £ s 2 v to me semi white to pi shade q=: -o noist adapt pink h able Q CQ CQ t ctf ctf Qj Qj C 3 qQ ollov c ~ Q 6 o $ V 3 go o 102 ollov noist adapt pink able ”0 1 Jo 0 < -1 1 . 5 noist semi Sep.-Nov. shade 5 O ’5 r d o to to C r* C r* semi pink to ‘o shade mauve o adapt red V able ’5 adapt scarlet sp & a able CD T 3 S Is I 0 £ Qj “ p Is äi,: ; 5-qz X 2 Q A A ^ a. 6, k i h o5 ‘ Z Z O in<« <"> zg: s 1 , = i n c £ v £ _c « 1 5 § «3 * a f I "° £ £ — 2f & J N J ~ 2 2 2 2 2 1 I I S ’S 1 'S 1 1 S*i* S\£ *.£ - a - c - c d-> - C d > SZ c/5 ""C X'O -C "o -C fl3 c /5 c/ 5 c/ 5 c/ 5 cS cS rtf rtf n3 Qj Qj Qj -O w *—■ _o w > , n3 CT3 .2 > ,.£ - .2 C/5 ^ to to £ to H ^ 2 4 = a 2 ’ o "2 ’2 ’ o ‘ o £ -S -5 = = -3 E Cd CTj r<3 CM + CM CM £ S :l* s 3 - g -::• .0 A g C/5 ^ 03 C C/5 s i l - u . L | - 2 r- ^ '"trj 'C 1 1 11 Sj-S S £ « I E a £ • s 5 J § c - 5 L j > . £ § E 1 • • c3 • . . . ct3 . C • 1 1 1 U p J UCJOCJUUCJUU u u Q w EO £0 103 £ f u ,3 o 33 G <3 11 8* o sp sp o 2 a-w tu C/5 sp-su late sp Sep.-Dec. Mav-Nov. Jun.-Oct. Aug.-Nov S I £lost of ye C <% u U _. .S TJ 1/ 3 ^ &■ Si a £ o "C *- O ~ lc 22 o £ 33 *■' -C pink white white * * cream cream cream tu U yellow deep red ^ l f ink to scar f ^ Ctoj 2 V >, le le le apt- le apt- apt- apt- * I I I J*i sun sun ~a _q sun sun sun sun "O X "0 X w "OXcd cd "OX cd cd n rs cd cd cd cd V c V jj jj o 3 _o *—> $ w .2 cd cd V *cd C/5 o *g ^ -::• •::* % < L -QI g* cd 2^ 2 a I g «is« i l " ° n ^ 2 I 1*11 1113 g 2 '5b U2 -CC Sc g fU I 9. ______J J "5c . 2 is . . s •% a ib d d d d d odd XXX 3 i i 104 cn U U < u £ % J3 C QJ H L if) QJ c/5 & • Sw i l ' l w CL3 rd3 CL3 03 3 ■g .3 "o - re !/l !3 1/1 ä . Ü -O o > Cl 3 3 >• O CL " Q L- £■ C /5 CL T 1 3 ‘o ^ 1/5 jj ;• ü L c rC s d Ü ~ £ Z 2 c V rL 30 15 O O£ .3 3 2 §oj JL 3L -3 z J I 2 3C ^ ~ h > ° T 1 £ £ —V * 4—> 0-» e- 3 >• 3 3 CL I |i " 2 U 3 r r- C- <— 9-3 3 3 ~ r c/5 5 ^ i " 5 1 * -2d ^ 2 ~ a _c 3 3 3 3 3-0 33 i f i 1 CS c^rdcrjr^cdc^ re re r« rcj 3 3 3 £ I £ C / 5 C /5 C /5 C /5 5 o c / 5 1 2 L r- *- 'o ‘o '5 '5 Is >—• C/5 r- ■ JS 3 .2 3 £ 3 3 T3 o o3 c £ 3 C /5 % % O 2 £ s '1/5^5 hp P V > C/5 p S ' | 2 2 £ £ d g £ Si 53 3 _3 £ 3 £ 5 2 rs 2 2 s 2 u ^ SH *c U C/5 2 3 5 2 2 2 « Qj , 3 • r* ^ y b g. -O a s 1 s c S 3 3 5 3 I CTj u o f N 2" CL 2 §: £ 3 S a-« T3 105 c/3 . U . u u. 33 £ w % o o O O O £ fl/ c t- a * c c 3 cb Species Spre; I 2 3 3 3 3 3 3 3 3 3 3 T 3 C y j * § £ _ ■ ! S ,2 cr3 3 3 ’S 3 3 <-2 4 0 " be 3 3 3 3 3 b j He b cb cb ° 106 ’o O o o ‘ _ # 3 3 - ? , o o to to to £ £ c £ * * C d C* r*' r* S S 5 c «5 53 - g.'S £ f c £ ~ s p - s u 2 s u n i r p l e e S e p . - J a 1 - 2 a d a p t r e d a b l e a £ • s s s si - C f- 3 3 C £ > s u n h i t e O c t . - N i 533 I I 1 2 S ' S 2 a d a p t r e d O c t . - N ' 2 . 5 3 £ . 1 T 1H a b l e z 3 . D ‘o o ' o ' = Q > cy £ 2 . Q c 2 £ E l c 2 2 ^ c 3 c a d a p t § : P i o o a b l e 3 3 3 3 to s . > * s o o £ N CN CN V o £ c £ *—> / C/5 c/5 £ £ * * <3J s e m i s h a d e 33 o V $ w ^ N 3 3 33 , o a, l e 3 3 "5 J £ s h a d e 8 « egbS .2 - . i x w H w c ix di a. tc J = £ 8 £ * o = b g .5 -5 £ £- £ £ £ £ - , j *1» Qj , J-< 8 jy w 3 g £ £ O O C CQ ,, C Qj C ^ £ ^ 2 S c c S ^ 2 ~ a Ü a ~ ~ 1/1 8 C 6 c ’odoci d J •c £ Tj j j u c ^ u u V d oocQ O^' o-axi x a - jo '^ ^ 'O c . S -o-o-c-Q r3o3c^o3c/5 c/ic^c^^Jc^c^rt -I 5 £ * > a 5 - j* ‘o j= Ol 3 QJ £ 2 2 bb >, o £ O j * jü cl g'S *2 "o c -a -c iO H 2 !U V ‘o •K % t £ £ £ H t/3 C/5 £ — be > » be £ 2 S ■ / C5 C/5 C/5 C/5 - d C r j Q ^ ^ ^ 0 y i s is is T ^ a. ^ ^ a. ^ < ö ö S 2 t O 't O O S p | o d — d -o ~ "o ~ 3 2c1/1 “ , _c o >, is < ■ - 2 -■ bJD c/5 c/5 d " c 2 c 2 = = x c 2 - 2 3 3 3 0 0 o S x r- to < is > “ o _ 2 ’".2 c/5 < < r- 108 ”o jo z < "O ‘o 3* >n s 3 >, c c ^ < cd c C / C5 / C/5 C/5 C/5 C/5 S' o l Qj cd u lc O 3 "O o — | ~o '5 > 1:1 in / C/5 C/5 X 1 S "5 "5 S dr O < V & qj E § § S 5 >'Z= = cue. ? < "O "O TO 5 c 'c ‘c '5 5 rs b£ o Z S' 25 2 o - s - j r • bC u .3 . •u /— • — £ ^ b£ ^ , & ~ 3, o o is c = S < < < 2 2 2 2 / C5 d f C/5 C/5 1/1 1 / i « 'S S' S' S' 2 u L 2 cL cu 4 d c S Cu * 4 I £ 2-3 C/5 C/5 iL o - - - - c 3 E 3 £ l t 1 CO c cd ~cd co co d Sf < & g to c £ / C/5 c/5 o o W W s Ö c/5 / > C/5CL ep.-O < 3 cu is - /5 C w-sp 2 - 3 ^ O C "5 ’S -.2 ° o >. 11 y I ,2 " ' 5. O r- ti b >*> O;s C IX ° < 2 U TO 2 .2 M) 0 S- jc £ O t I C 5c g 1 _ cu g 5-^ T OJ h 0 II £ b * O u -- b b b sc £ -c U1 Us tSO ~>, 1 I l - s - S 1 1 1 3 § S\g I I 2 5 C/5 C/5 C/5 £ TO . £- C/5 C/5 C/5 3 I 2 o ’o a-S o O 'I I 'I 5 2 2 I * ra TO* “ '5 c -cTO "0 b OJ £ £ r3 'Va c -c % •C t= sc b 2 3 X TO 3 * *«« 3 II 109 Species Spread Situation Ex- Flower Flower Extra Comr m posure Colour Season adaptable semi- shade to sun S _9 GS I I •a I 3 g I § c .2 •c u -o ’ O % 2 S’ I = Cb -c bt. b CG 2.5 adaptable adapt re u u u able C X iX CC .§>.§>& -Q _ o- > • o-c b f £ If V X ~ X V .* s i.'* 2 s l - e D § b / C3 C/5 C/3 <—r- C/5 (—■ 111 QC — 'C n 4 dry sun yg .y 4 dry to moist sun LZ hr 3 5 moist sun 110 % T3 CO *? t ■I ü l g • w O ww Q 3 -Q 2 . 0 • 9 • o 3 i s ® 5 3 | g S S S be C c/3 „ 2 c dry sun & > o tb cb f CO 'f & Ö P £ . o 03 -2 £ moist sun £ < O G o \ moist sun to semi shade -5 _c ’S _c ’S € . « ? « t '. o* o b 3-4 adaptable sun bb ° = c T - -C ’.«Ü Go? o ’G b -::•cb I b ~ , ~ b jLTlo 3 moist sun G!§> C/5 J £ 5 g 2 dry sun cl I 3 moist sun * u i I 2 *p be be Ve i t c C L .3 b i r d s s h a d e £ d C Q. - e s o O 2 CL CL T 1 < T> C/5 CO C/5 k/ >■ 3 % I § < o .£ £ ,_ _b _ 2-i-i2 i -S •= I ■; 3 2 ■3 -c = q = ' 3 "3 3 c « 3 G 5 £ -C £ rt £ .1111 =3 ^ 2 2 2 £ rt 2 to S' JJ JU "3 o C/5 *-* w (“) ' f-m «—< w O co CO . 2 . 2 b CO ^ CO CO CO ’o 1 0 ’o 0 0 3 ’o CO £ 3 3 « 3 2 1 I C "C £ ’o 03 b £ s * *o 04 04 CO «1 CO CO CO (N 1" tx 04 % j 4 1 " 5 ! 2 sg* Jill 2 bp 2 3 " ~ ^ o •C •2 2-2 g P ;c ^ S| a 3 J 3 ■£ b 3 5 ' I 2 & 3 -S fc I II" S 5 Q- c . . . - 2 j J 2 5 2 2222 IJ 2" 111 J ( LANTS 10m and TALLER W 2 2 O .2 * rs)U* E £ c E _0 re 33 £ % s ° 'S \ u I c/T c E g re £ s- O U I "5 "5 = Q ^ 5 *■ Z < 2 ^ .5 ^ .2 Ün b O- > bb ^ 0 3 S 3 S I S 3 'S >-_2 3 3 3 C D 6< < < U SO S *-“■/— r-O 3 ~ X3 ~ /3 lie !/> U - Sc"? - —X c_X O X U — U — C 1 3 • 5 5 £ h 1 r c oj 5.6 t /5 X c c X X C 3 /5 IE c I « « v 5 5 "= 3 1 1 5 = & i= = . £ 3 2 QJ O y S 2 JS *u 5 r £ zr O X X O r 2 x x £ 3 3 - 3 I 5 : = = = : = £ i ■ V 5 o C 5 /3 = - C X Z- C CJ O ~ r- r~ C /3 C E . £ . C ÜÜÜJuiuiui_3uiE;i3 3 3 /3 5 5 5 5 E c E c 3 ' 3 i3 33 re re e b e b 3 tu 5 0 112 SsNl re ‘ ' ^ ^ '—‘ ^ ^ O'. ‘O l C .1 & & I I 0 /3 /3 £^ — ^ b£.^ QJ 3 2 0 iS c ‘0 5 2 3 C E E C J c Jz U “ X XU C 0 ' re re < /3 5 . > /3 ■ "T C — e re re 3 £ - •— s c '—’ Ü X O € * /3 0 C ~i 5 5 ~ ~ 0 2 0 i t o t JS 3 /3 ~ ~ C u b r "re "re £ 3 1 E E - b b H C tb = 0 $ ' > /3 X X /3 3 0 S re -S 3 & C 5 5 3 0 /3 S re . — 2 e g re 5 LX 0 3 C - - L> c '-> r- b b E E A C/ CA /3 e _g re 5 C '= . c x o re CJ _ m o i s t 2 f— g re 3 'S i E 5 0 X C 3 /3 Q C/3 g 3 a p t a l ' | -r. re b £ bC h § 'E — a . tC /2 2 be a s 1 So be be c~ o < Q •f1 -^c u be U 3 C/2 Qj 'cl V w w II U J c 1c 1c S = u O C /2 b £ £ C >• re — p\ o r*\ « 5 i4(TJcerdre^3^3cT3n3^3c^cec^ i4 i s f i I s 14 * 5 JL — o jl — w — .2 5 2 ■§ *§ 2 cts :± .* ctcL: S’ S’ 5 ?T S’ - f = = ’S 'S s ^ OC oc OC oo OC 'sC Ö — r e •::• -::• / 2Z •::* E 2 I * J 'E _ 0 •::• .1 2 ji 5 S: c£ y ■g § j5 u — ~ X x _ Se s x c/ £ 1 ui ui ui ui ui ui O H 113 Growing native plants, whether by themselves or mixed with exotics, is becoming increasingly popular. A wide range of species can be grown in Canberra and this book tells you how to grow therti. Mr Butlers sensible advice dismisses many of the myths about their needs and cultivation and gives much practical information. Mr Butler's work at the National Botanic Gardens in Canberra has given him a unique opportunity to study the growth of native plants in Canberra’s climate and to pass on this knowledge to the reader. Canberra Companions are published by the Australian National University Press as a contribution to the cultural, educational and recreational life of the immediate area served by the University. Titles available include: Rambles around Canberra edited by Allan J. Mortlock and Gillian O’Loghlin Tales and Legends of Canberra Pioneers by Samuel Shumack Episodes of Old Canberra by Ged Martin Street Trees in Canberra by Audrey H. Edwards Undiscovered Canberra by Allan J. Mortlock and Bernice Anderson The Australian National University — People and places in a landscape Canberra’s Embassies by Graeme Barrow Fishing around the Monaro by Douglas Stewart The Canberra Handbook Beyond the Cotter by Allan J. Mortlock and Klaus Hueneke Australian National University Press Canberra ISBN 0 7081 1079 7. o * s 5 Species Spread Situation Ex- Flower Flower Extra Commei m posure Colour Season X < < ‘o Q - be CL c £ V c' CQ bb V O adapt able 9 < 2 ^ JS CO 2 1 § : % u c c u .£ S « . be>. Q 3 £ CQ 2 c j 22 O “ gold h - noist sun T