montana at an altitude of 3,000m in the pine forests of northeast Mexico. The leaf rosettes flush red as they prepare to flower and die Searching for hardy Agave

XOTIC OR SUBTROPICAL Informed by three maybe the rule, not the exception. gardening style is currently So, what then of our tree ferns E enjoying something of a visits to the mountain and bananas? renaissance. Certainly, with climate- change models predicting milder woodlands of Mexico Confronting drought winters and hotter summers this and cultivation Necessity has already forced me to previously marginalised aspect of confront this problem. A devotee of gardening has suddenly grown up experience this style of gardening for over 20 and become appropriately respectable. in eastern England, years, I was first seduced, like many But scientists warn us that rainfall initiates, by large jungly leaves. I live patterns are set to change with little PAUL SPRACKLIN in coastal Essex where, in an average falling during the very period our reports on with year, we can expect just 50cm of gardens need it the most. Hosepipe rainfall. Big leaves equals big water restrictions become a real possibility; hardiness potential bills, not to mention the time and

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effort involved in supplying it to the here, or, indeed, in other areas of Mexico. I cobbled together the . I started seeking out plants England? A little research soon throws itinerary for a trip and in November that are suited to arid growing up some interesting data. Plants from 2004, together with friend and conditions yet fulfil my need to grow the central US deserts in particular nurseryman Toby Shobbrook, dramatic plants. And I found show immense cold tolerance: figures headed for the mountains of succulents. Imposing succulents northeast Mexico. The first, as it that, grown together, still paint an turned out, of three such trips. exotic picture yet outlive any hose A few kilometres southwest of ban. Succulents such as yuccas, Ciudad Victoria in the state of dasylirions, nolinas…. and agaves. Tamaulipas, just off highway 101, is located the small town of La Peña, Familiar our rendezvous point with Richard So far, so good. But ask succulent and from where we took a good dirt collectors which agaves are road into the mountains. Rapidly most suited to growing outside and, swallowing altitude, we left behind in reply, you are most likely hear the yuccas and dasylirions of the ‘That’s easy. None’. What little semi-desert plains to above 2,300m precedent exists for growing agaves where the habitat changed fairly outdoors is mainly found in the abruptly to a forest of pines, dwarf milder areas of southwest England. oaks and arbutus. Wander around some of the Cornish It was here that we encountered

Paul Spracklin seaside towns and you will see the the first of two woodland Agave familiar Agave americana often species. Agave gentryi is a variable

bursting its way out of a fisherman’s Spracklin Paul species found throughout northeast tiny front garden like a cuckoo in a Agave montana encounters cool summers and Mexico, both in moist woodland, as wren’s nest. frost and snow in its temperate native habitat. here, or on arid exposed mount- Look more closely and some of In cultivation in the UK it has withstood -10°C ainsides. Typically it forms sparse those greener A. americana are of -30°C are quoted for species such rosettes, around 1m in diameter, of actually A. salmiana – the sinuous flex as A. utahensis. Easily hardy enough dark green, often triangular-shaped of the leaf tip, the satin sheen of the for my occasional -10°C winters, you leaves, sometimes ferociously armed leaves, and the slightly purple tones would think. Sadly, the situation is with large marginal teeth. Some have on the leaf margins help distinguish not that straightforward. Although only small teeth, some are consider- it. Some – the fatter, wider-leaved hardy to extreme cold, A. utahensis is ably larger, all are recognisably the plants – are A. salmiana var. ferox (syn. very tricky to please outside as it is same species. These plants are A. ferox). This variety could be seen prone to rotting during the winter. abundant to around 2,700m from flowering on the Falmouth seafront, Superficially, we seem to have a where, suddenly, it is replaced by Cornwall, in 2007. paradox: moisture-tolerant agaves another agave. And just about the only other one are hardy only in the mildest gardens, And what an agave! Imagine a seen outside enthusiasts’ gardens is and species hardy enough to grow sempervivum 1.5m across and you A. mitis, a modestly-sized, pale green through England are unable to cope begin to picture Agave montana. It plant with very small marginal teeth with winter moisture levels. There has scores of leaves packed densely and a ‘foxtail’ style , must be some kind of middle ground, into a rosette almost full to bursting. rather than the usual ‘christmas tree’. surely? There is, and it is at this point Although frequently spilling out These agaves have one thing in we head for the Mexican woods. onto open, sunny hillsides and road common – they are fairly moisture cuttings, it is mainly found deep into tolerant and, although not the hardiest Mexican adventures the woods as understorey. And these of the group, are among the most My reading directed me to Mexico, woods are temperate: this mountain suited to growing in the wetter, mild- home of the Agave, and to my mentor reaches 3,020m with these agaves er regions. But here I am over the in all things Mexican: the Texan only being found in the top 300m. It other side of the country – colder plantsman Richard Travis, a man is cool in summer and cold in winter and drier. What plants can we grow well travelled throughout northern – reaching -10°C in most years, ➤

September 2007 147 HARDINESS ASSESSMENT often lower. Agave montana are on the moist side of the mountain and are routinely covered in mist, drizzly rain, frost and even snow. The oldest plants in these populations, probably 30–40 years old, show no sign of previous cold damage to their pristine rosettes. Both species are now filtering into cultivation and represent, without doubt, the best agaves that can be grown in England, and elsewhere in the temperate world. Two year old seedlings of A. montana have just seen through a winter temperature Spracklin Paul Agave gentryi occurs at a slightly lower altitude than A. montana but occupies a similar habitat of -10°C in middle England in 2006/7, so it looks very encouraging. identified and propagated by one or how exciting this plant is – not only two keen nurserymen but at the one of the most beautiful agaves Species to grow outside moment the situation is less than but with huge garden potential. Trying new plants is nothing new to satisfactory. Nevertheless, here are Large plants should prove hardy Cornish pioneers who have been my recommendations for trying to maybe -15°C. gardening on the edge since it became outside, in order of suitability – a leisure pursuit. But others in less particularly hardiness. I have ignored Agave gentryi benign climates have recently joined A. americana completely – for me This species was also discussed above. in. For example, Bob Brown, at his there are far more interesting and In the USA a particularly fine clone, nursery Cotswold Garden Flowers in more appropriate species to grow. A. gentryi ‘Jaws’, has been tissue- Worcestershire, has a bed of succulent cultured, and is available in the UK plants that is left completely to the Agave montana occasionally. The species and this elements. Nick Macer, of Pan This species was discussed above cultivar should be hardy to -10°C, Global Plants, has a display garden in but I feel it is impossible to overstate probably lower. his Gloucestershire nursery with many succulent plantings being trialled. There is also a growing array of enthusiasts from all over the land seeking something new, exciting and rewarding. Gradually, an idea of what species will grow here is emerging. One thing that seems clear, though sadly unhelpful, is that hardiness for many species seems to be clonal. To say that A. salmiana, for example, is hardy would be somewhat mislead- ing. Some plants of some forms of A. salmiana are incredibly hardy to cold and damp combined, but others disintegrate into a pile of mush with the first frost. Given its enormous range in the Mexico – it is cultivated throughout the central highlands – I suppose this should be expected. Spracklin Paul These hardy clones are being In the wild, Agave mitis favours rock faces where it roots into crevices that act as seepage lines

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Agave mitis (syn. A. celsii) However, variation in the species, Like most agaves, this is variable but throughout its range in the central always attractive. Typically in cultiv- Mexican highlands, appears to be ation it has open, apple-green rosettes, continuous. The most impressive to 60cm in diameter, formed of plants of var. ferox I have seen are in lightly-toothed, slightly incurving Falmouth, Cornwall, and on Tresco in leaves. In the wild it is found plaster- the Abbey Gardens. The more ed vertically onto rock faces follow- tender clones of this species are ing slight seepage lines and hence hardy to -3°C but the tougher ones deals with moisture quite adequately. can cope with -15°C. It is also often seen growing in shade though I would default to a sunnier Agave bracteosa spot when trying it outside in the This species is unusual as far as UK. It is not hardy in colder regions agaves go; Gentry (1982) even but can survive down to -8°C. Horticultural Photos suggested it could be placed in a new Agave bracteosa rosettes are not monocarpic There is a particularly choice var- genus (along with A. ellemeetiana). It iety, A. mitis var. albidior (syn. A. celsii I have seen named A. mitriformis has thin, almost wiry leaves, un- var. albicans), that is almost chalky (usually regarded as a synonym of armed on the margins or tip, and the white, compared to the usual pale A. salmiana) that are not very hardy. upper surface is convex. The offsets green. It is rarely seen in cultivation At the opposite end of the scale is a are produced from axillary buds rather but commonly mislabelled – if you dwarf, chunky variant identified pre- than from underground suckers and are unsure what plant you have, it is viously as A. coarctata (again, now a each rosette flowers repeatedly rather not var. albidior. synonym of A. salmiana). The latter has than monocarpically. grown in my garden in Essex, undam- This species is very distinct, very Agave salmiana aged by cold, for eight years. attractive, and unexpectedly, quite With the disclaimers relating to Intermediate between these two hardy. I know someone growing this hardiness already discussed above, extremes is A. salmiana var. ferox. In near the renowned frost hollow of this species offers some of the best horticulture, this name seems to be Rickmansworth, London, where it agaves to try outside. There are applied to any variant of A. salmiana has survived -8°C. variants with long, narrow leaves that with wide leaves and large teeth. Agave parryi This species is more widely available than most, and has four recognised varieties. Agave parryi var. parryi is possibly the best candidate for hardi- ness, surviving temperatures below - 10°C, and it is moisture tolerant. It is the largest variety, making rosettes, over 1m across, of comparatively long, grey leaves armed with black teeth and a terminal spine. Agave parryi var. huachucensis is a little smaller and more desirable with wider leaves that seem, somehow, perfectly in proportion. Smaller still, and with even wider, almost round leaves, is A. parryi var. truncata: arguably the most handsome and certainly the most sought after.

Photos Horticultural Photos Unfortunately, this latter variety is Variants of Agave salmiana in cultivation with broad leaves and large teeth are usually called var. ferox the least hardy, maybe only down ➤

September 2007 149 HARDINESS ASSESSMENT to -6°C or so. All will sucker to form small colonies (or spare plants) in time and are worth trying.

Agave havardiana & A. neomexicana Agave havardiana is difficult to distin- guish from A. parryi var. parryi but is an equally good candidate for growing outside. The main differences are in floral characters. Distinguishing agaves in the vegetative state is difficult but the marginal leaf teeth of A. havardiana tend to be larger, darker and recurved. Agave neomexicana is similar but with narrower, even more silvery leaves and often with dramatically Spracklin Paul Agave parryi var. huachucensis is favoured for its broad grey-green leaves and neat habit enlarged marginal teeth. In UK conditions both should be hardy to Agave parrasana The leaf surface is often beautifully below -10°C. This species is small and chunky, marked with white bud-printing with rosettes to 80cm in diameter. marks. It is hardy to -8°C or lower. Agave lophantha, A. lechuguilla and The wide grey leaves, especially A. xylonacantha broad at the base, and the variable var. mirabilis In the wild, A. lophantha represents a marginal teeth make it an attractive The species is widely distributed in variable and widespread complex. In plant. I know of pristine plants grown central Mexico but this variety, cultivation it is usually represented in Surrey for 12 years, yet one of my occurring at about 2,500m in the by plants with open rosettes, to own died in winter for no apparent montane cloud forests of Veracruz, 80cm across, of narrow mid to dark reason. It is hardy to -8°C or lower. is one of the most dramatic and green leaves, mostly with a median massive of all agaves. The rosettes stripe of pale green. These are edged Agave filifera can reach 2.5m high and 4m wide. with a horny brown margin that is, This species has a slightly different It is not yet available commercially. itself, interspersed with small teeth. look to the more familiar agaves. It Agave lechuguilla is similar but with forms a dense rosette, to 70cm Agave ovatifolia narrower leaves, less pronounced across, of flat, incurving triangular From further north, near Saltillo in marginal teeth and a more untidy leaves, the margins of which sport Nuevo León, Agave ovatifolia is habit. curling white fibres and no teeth. another large, beautiful, hardy and Agave xylonacantha, as grown in Europe, is also similar to A. lophantha but with ripsaw-like teeth – a mixture of large and small, pointing in two directions. Plants grown under this name in Europe, including the UK, do not match plants in the wild. Genuine A. xylonacantha is larger with more open rosettes that have less leaves, and are a dull olive green compared to the brighter green of cultivated material. All three taxa in cultivation are quite hardy, to -10°C or lower. Spracklin Paul Spracklin Paul Genuine Agave xylonacantha in the wild Agave xylonacantha as grown in Europe

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Propagation Most Agave species can be propagat- ed from the copious plantlets produced on underground runners. These should be detached, allowed to dry out for a few days, potted into gritty compost and then grown on. A few species produce bulbils on their – a ready and quick method of propagating. All species can be raised easily from fresh seed. Indeed, some can only be grown from seed: A. montana, for example, does not usually produce suckers except to a limited extent after flowering. Greg Starr Greg Some taxa have been microprop- The blue-grey leaves with large marginal spines make Agave parrasana a desirable species agated, such as A. gentryi ‘Jaws’ and damp-tolerant agave. This species I grow mine in raised beds with the A. ovatifolia. Particularly good clones was named in 2002, is already in rootball sitting on a generous layer of other agaves, such as A. atrovirens tissue culture in the US, and is just of rubble. I then backfill with loose var. mirabilis, should also be consid- becoming available in the UK. rubble, filling the gaps with a 50:50 ered for this method. However, beware of nurseries offer- mixture of 20mm all-in ballast and ing plants with green leaves which 10mm pea shingle. I do not recomm- Conclusion may be incorrectly named; genuine end any soil at all. If you live in a Climate change will force us to adapt material I have seen in the US has milder region you may get away with our gardening practices. Living with intensely silvery foliage, even on using a richer mix, but I find growing summer droughts is something many young plants. them hard is best. If the medium is must learn to cope with. One way too rich the roots will rot each winter forward is to garden with succulents, Cultivation forcing the plant, at best, to re-root a group containing some of the most The most important factor in success- each year or, at worst, to die. dramatic and architectural plants ful cultivation of Agave outdoors is Apart from that they are undem- that can be grown outside in the UK. drainage. In the wild they get season- anding plants to grow. A position Judicious choice of species ensures al rainfall with very little in winter. in full sun is most important, as is survival of our damp dark winters. The quicker you can speed the pass- good air circulation. Some species, Agaves are an important part of age of water past the roots, the better. particularly those from higher rain- the mix and, despite historical fall regions, may actually benefit prejudices, it is apparent that many from a little extra water during species thrive when liberated from spring and summer but most will their pots and exposed to the get by without. Those that benefit elements. Certainly, some of the include A. atrovirens var. mirabilis, most exciting introductions are still A. mitis and A. salmiana, and to come. ■ probably A. ovatifolia, A. montana and some provenances of A. gentryi. PAUL SPRACKLIN is a garden designer An annual top-dressing of slow- with a specialist interest in gardening release balanced fertiliser is all they with succulents

need by way of food. Weeding REFERENCE presents the biggest challenge – in particular keep a look out for Gentry, HS (1982) Agaves of

Neil Holmes Continental North America. University rhizomatous weeds in pots before of Arizona, Tucson Bud-printing marks are visible on Agave filifera planting out.

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