7.6 - Trees and Ornamental Planting Materials and Specification It is recommended that the city centre’s existing trees are evaluated on their individual merit to determine whether they should be retained, 7.6 - Trees and Ornamental Planting... removed or replaced. Consideration should be given to their current appearance, and condition Appropriate Use of Plan ng and future management implications (particularly where they are close to buildings). Existing trees Trees and other ornamental plan ng within urban environments offer a number of should be retained, wherever possible, where they benefits that improve the visual and environmental quality of the public realm. Having add value to the public realm, and appropriate management works carried out. said this, the use of plan ng is not appropriate in every loca on and the aim must be for quality over quan ty. New plan ng should only be undertaken where it would make a Another important factor in carrying out this posi ve contribu on to the public realm, such as: assessment is whether these mature trees are obscuring important views. For example, the views • Providing a focal point or framing a focal point or Strategy in Relation to Existing Trees from the City Walls would benefit from the thinning view; of Sycamores in some locations. There are a limited number of trees currently found • Demarcating routes and highlighting key with Chester’s city centre due to the narrowness transport corridors, through the use of of the streets that make up the historic urban boulevards and avenues; core. The mature trees that are found tend to be associated with open spaces around the Cathedral, • Improving the scale and proportion of very wide Grosvenor Park, the riverside and canal. The streets and spaces; majority of these mature trees are Common Lime (Tilia x europaea) and this distinctive tree • Acting as a sound barrier to reduce noise levels contributes a great deal to the city’s character. A on roads; number of these trees have been heavily pollarded and pruned in the past to try and control their • Improving air quality and helping to neutralise growth, particularly where they are located close to carbon emissions; buildings.
• Providing shelter from wind, rain and sunlight; Another tree species commonly found along the route of the walls (where it has had an opportunity • Improving the urban ecosystem by supporting a to self-seed) is Acer pseudoplatanus (Sycamore). variety of wild life; and Although not a particularly valued species, these trees do contribute to the experience of walking the • Helping to screen ugly or blank facades. walls. Lime Trees Along The Groves
358 7.6 - Trees and Ornamental Planting Future Strategy
As previously identified, tree planting along every street within the city centre would not be appropriate due to the limited space and importance of the architecture, nor is it needed as the majority of streets in the historic core are attractive routes. It is therefore proposed that new tree planting is focused on the following locations which are illustrated in the planting strategy shown in Figure 7.25 overleaf.
It is important to note that the strategy shown in Figure 7.25 is aspirational and is subject to further detailed investigations being carried out to determine feasibility. In addition to the strategy outlined there may be other locations where it would be appropriate to carry out street tree planting in the future. In any situation where space is limited and the greening of a street is considered important, planters containing a mix of shrubs and perennials should be used.
Example of Perennial and Tree Planting in Chevasse Park, Liverpool
359 7.6 - Trees and Ornamental Planting Figure 7.25 – Proposed PlanƟng Strategy
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0 100 200 metres N © Crown copyright. All rights reserved. 2010.cwac os licence number 100049046 360 7.6 - Trees and Ornamental Planting General Principles • Size and Scale: Street trees should be specified Siting as semi-mature (20cm girth +) specimens as a Trees should only be planted where it is appropriate minimum, with a stem clearance of 2.1m where and consideration should be given to the following they are within a paved area. A more robust factors that will influence siting: tree will stand up to the impact vandalism. The future height and width of a tree should be • Adequate space for mature canopy and roots considered to ensure compatibility with the scale of a space at full maturity. • Natural surveillance/position of CCTV cameras • Form and Habit: Canopies should display and • Impact on night-time lighting levels generally retain a tidy and balanced shape. Street Tree Planting George Street, St Helens • Views of important and attractive building • Canopy density and leaf size: Where larger facades trees are specified, species should be selected Tree Avenues to Strategic Approaches and Routes that have more open canopies so that light can • Underground services (in important locations and penetrate through to the street below. Smaller In comparison to the city centre core, a number where budget allows consideration should be trees provide the opportunity for a denser of Chester’s strategic approaches and routes are given to rerouting and grouping services in ducts). canopy. The generation of plant litter (leaves of poor visual quality and dominated by vehicles. and fruit) will be a maintenance (and health and Avenue tree planting should be used, wherever • Proximity of vehicle and pedestrian routes safety consideration), as well as species that are possible within verges and central reservations, to prone to honeydew. define and raise the visual quality of routes. This Species Selection will help to improve first impressions of the city It is essential that the tree species selected for a • Aesthetics: Trees should be selected for their on arrival by car/bus and also create a pedestrian particular location is an appropriate choice. To help high amenity value and seasonal interest. friendly environment for those walking into the city enable this choice, the following factors should be Feature trees should be selected for their across the inner ring road from the railway station considered: distinctive colour and form and for their year- and residential areas. round seasonal interest. • Growing Requirements: Some species are more In order to successfully achieve these objectives, suited to urban environments (e.g more tolerant The following pages set out the tree species that avenue trees must be of a single species at a of compaction around the base of their roots). have been selected as suitable for planting within consistent spacing along a route. It is anticipated Shallow rooting species can cause disruption the city centre under the hierarchy set out in the that trees along these routes would be medium- to paved surfaces (e.g Prunus spp.). Light and planting strategy. These include Lime species/ large sized (see species table for appropriate shelter requirements are also relevant. It is cultivars chosen to reflect the high proportion of examples). Where scope to accommodate trees is important that in response to climate change, existing Limes found in the city centre. limited, trees should generally only be planted if at species are also selected for their ability to least a row of three trees can be accommodated at withstand drought or waterlogged conditions. any one location.
361 7.6 - Trees and Ornamental Planting Suitable medium –large size avenue trees for strategic approaches and routes
Species Height and spread at Growing requirements Form and features maturity
Acer rubrum ‘Armstrong’ 10m height, 3m spread. Will tolerate alkali condi ons, but not at its best in Large, narrow tree. Drama c red autumn colour. (Red Maple cul var) these condi ons.
Carpinus betulus ‘Streetwise’ 9m height, 3m spread Generally tolerant of a wide range of condi ons Striking orange/yellow autumn colour. (Common Hornbeam cul var) (although prefers soils to be not too light/dry)
Tilia cordata ‘Streetwise’ 10m height, 6m spread Suited to difficult urban environments. Medium/large tree. Shiny dark green foliage. Neat balanced form. No problem (Small Leaved Lime cul var) with aphids in summer.
Tilia platyphyllos ‘Streetwise’ 12m height, 4m spread Suited to difficult urban environments. Large tree with upright habit. Striking red shoots in winter and purple/brown (Broad Leaved Lime cul var) autumn colour. Locate in areas of so landscape – as not aphid free.
Tilia x euchlora 10m height, 6m spread Tolerant of a wide range of condi ons Medium sized tree, dark shiny green foliage. No problem with aphids in summer. (Lime species)
Tilia tomentosa ‘Chelsea Sen nel’ 10m height, 5m spread Tolerant of a wide range of condi ons Large tree with a rac ve weeping branches, but generally columnar form. (Silver Lime cul var) Delicate leaves with silver underside. Aphid free
Acer rubrum ‘Armstrong’ Carpinus betulus ‘Streetwise’ Tilia platyphyllos ‘Streetwise’ Tilia x euchlora (Red Maple cultivar) (Common Hornbeam cultivar) (Broad Leaved Lime cultivar) (Lime species) 362 7.6 - Trees and Ornamental Planting Street Trees to Key Links Suitable small – medium size street trees to key links
There are a few key links into the retail core and to Species Height and spread at Growing require- Form and features key destinations within the city that currently lack maturity ments definition. The use of street tree planting along these routes would help improve the quality of Acer campestre ‘Streetwise’ 7m height, 3m spread Tolerant of all soil Medium tree with neat, upright habit. the streets for pedestrians in particular, creating (Field Maple cul var) types Brilliant yellow autumn colour. attractive vistas and encouraging visitors to explore further afield. Again, consistent use of species Carpinus betulus ‘Frans Fontaine’ 9m height, 2.5m spread Best in well drained Medium tree with narrow upright habit. will be important at these locations using regular (Common Hornbeam cul var) and rich soils, but can Dark green leaves, yellow autumn colour. s ll thrive in sandy or spacings. It is anticipated that trees along these dry soils. routes would be small-medium sized (see species table for appropriate examples). Pyrus calleryana ‘Chan cleer’ 8m height, 3m spread Very hardy and Upright, dy form. White blossom in (Ornamental Pear) drought tolerant. Well spring. Glossy green leaves with good suited to plan ng in autumn colour. streets.
Tilia cordata ‘Rancho’ 8m height, 3m spread Tolerant of a wide Small/medium tree with upright conical (Small Leaved Lime cul var) range of condi ons/ habit and a rac ve dark green glossy situa ons. foliage. No problem with aphids in summer.
Acer campestre ‘Streetwise’ Pyrus calleryana ‘Chanticleer’ Pyrus calleryana ‘Chanticleer’ Tilia cordata ‘Rancho’ (Field Maple cultivar) (Ornamental Pear) (Ornamental Pear) (Small Leaved Lime cultivar) 363 7.6 - Trees and Ornamental Planting Ornamental Tree and Other Planting to Spaces Suitable ornamental trees to spaces and gateways (ranging in size) and Gateways Ornamental tree planting should be employed at Species Height and Growing require- Form and features the key spaces and gateways identified in Figure spread at ments 7.25 to announce arrival and emphasise a change maturity in character of the public realm. Ornamental tree planting should be used in combination with Acer platanoides ‘Globosum’ 4m height, 3m Good on all soils Small tree. Striking mop head shape (specimens ornamental shrub and perennial planting, where (Norway Maple cul var) spread (except where prone to can become wider than they are tall). Good waterlogging). yellow/orange autumn colour. appropriate, as an integral part of the design of the space or gateway. Species should generally be Acer platanoides ‘Obelisk’ 10m height, 1.5m Good on all soils Medium sized tree with striking columnar consistently used, or at least used in bold blocks. (Norway Maple cul var) spread (except where prone to habit. Tree species in these locations are likely to vary in waterlogging). scale, depending on the space available, and will be Amelanchier lamarckii 7m height, 2.5m Tolerant of range of Small tree. Narrow upright canopy. Early spring selected for their distinctive, decorative features. ‘Robin Hill’ spread growing condi ons. - white blossom. Oval coppery red leaves (Snowy Mespilus) follow and rich red/orange autumn colour.
Betula nigra 10m height, 5m Will tolerate extremely Medium sized tree. Dis nc ve pink/orange (River Birch) spread wet and dry soils. flaking bark.
Fagus sylva ca ‘Dawyck Gold’ 8m height, 2m Any free draining soil. Medium/Large tree with ght columnar habit. (Common Beech cul var) spread Striking form suited for plan ng in so landscape as feature. A rac ve yellow/green leaves.
Prunus serrula 6m height, 4m Tolerant of range of Small tree. Shiny red/brown bark (par cularly (Tibetan Cherry) spread growing condi ons. a rac ve as mul -stem).
Quercus palustris 10m height, 5m Will not grow on alkaline Large tree with pyramidal form and a rac ve (Pin Oak) spread soils. habit. Leaves turn scarlet red in autumn.
Acer platanoides ‘Globosum’ Amelanchier lamarckii Prunus serrula Quercus palustris (Norway Maple cultivar) ‘Robin Hill’ (Snowy Mespilus) (Tibetan Cherry) (Pin Oak) 364 7.6 - Trees and Ornamental Planting Tree Planting to Surface Car Parks and Internal Suitable small size tree planting to surface car parks and internal side streets Side Streets There is a tendency for surface car parks surrounding the retail core to be devoid of any tree or other Species Height and spread Growing require- Form and features planting. First impressions of the city are often at maturity ments influenced by the views of these areas and the addition of tree planting could do a great deal to Malus trilobata 6m height, 2.5m spread Very tolerant of urban Small, narrow headed tree. Flowers white assist. Similarly, internal side streets within the main (Crab Apple) environments and wide Maple like leaves, with strong autumn perimeter blocks of the city centre provide access to range of condi ons. colour. some smaller businesses, as well as vehicle access Sorbus aucuparia ‘Streetwise’ 7m height, 3m spread Very tolerant of urban Neat upright habit. Bright orange berries to service yards. The use of occasional tree planting (Rowan cul var) environments and wide in autumn. along these side streets would help to screen less range of condi ons. attractive boundaries, enhancing the environmental Sorbus hupehensis 8m height, 5m spread Very tolerant of urban Small tree with bold compact canopy. quality of these routes and encouraging greater (Hupeh Rowan) environments and wide Foliage blue/green and fruits are white footfall for businesses. A consistent use of species range of condi ons. with nge of pink. across a single car park or along a street will help to prevent a haphazard look. It is anticipated that trees Sorbus x thuringiaca ‘Fas giata’ 6m height, 4m spread Very tolerant of urban Small tree, with formal ‘lollipop’ head. (Whitebeam cul var) environments. Pinnate, grey/green leaves with red berries along these routes would be small sized (see species in autumn. table for appropriate examples).
Enhanced planting to Grosvenor Park and Other Greenspaces Proposals for enhanced planting within Grosvenor Park are contained within the Grosvenor Park Conservation Management Plan. As well as enhancing existing planting through an appropriate management regime, new planting is proposed through the restoration and improvement of the River Terrace Garden and Quarry Garden.
In addition it is recognised that there is scope to improve planting in other greenspaces in the city centre.
Malus trilobata Sorbus aucuparia ‘Streetwise’ Sorbus hupehensis (Crab Apple) (Rowan cultivar) (Hupeh Rowan) 365 7.6 - Trees and Ornamental Planting Tree Pit Design and Specification The key elements of each design solution will • Rather than using tree guards, it is proposed include the following. that trees be planted at a suitably robust size General Principles (semi-mature 20cm + with a 2100mm clear stem) • Trees should be planted in the ground, rather • Tree pits should contain a suitable primary and anchored using a below ground tensioner than in raised planters. Planting in the ground growing medium, comprising a system such as and anchor system. Depending upon ground should ideally be in uncontained, free draining Greenleaf’s RootCell system (or equal approved), conditions Deadman anchors or alternative soil. which provides a load bearing structure used anchor systems can be used. Individual in conjunction with topsoil. A sand based load requirements should be discussed with the tree • Where contained tree pits are needed they bearing soil, such as Greenleaf’s Arbor soil/ product supplier on a site-by-site basis. should be as large as is feasible. For example, Amsterdam tree soil (or equal approved), is only the use of a single tree pit linking a row of trees recommended for use as a secondary rooting (in the form of a trench) is better than a series of zone underneath paved areas. smaller individual pits. • It is imperative to the survival of any tree to • Tree grilles/tree pit surfacing should be used to incorporate a drainage layer/soakaway to protect and aerate tree root systems and allow prevent waterlogging. rainwater irrigation. • The tree grille/surfacing should be supported by • Depending on the depth of the tree pit there a frame so that the surface paving is not bearing may be archaeological implications to tree down on the tree pit soil, which might lead to planting in certain areas of the city. The City compaction and potential subsidence. Archaeologist must be consulted prior to any works being carried out. • Watering of trees should be via an in-situ inlet pipe for manual watering or an automatic The key elements of a tree pit protected by a tree system. This will improve the efficiency grille and by tree pit surfacing are shown in the for watering large numbers of trees during details provided in Figures 7.26, 7.27 and 7.28. The maintenance operations. The inlet pipe should actual design and specification of tree pits will vary be protected when not in use, using a cast depending on the exact location, layout and species aluminium lid. Automatic systems may be able and all requirements should be discussed with a tree to make use of water collected from surrounding product supplier and checked with the appropriate drainage systems. It is important to note that council landscape architect and engineer before irrigation pipes also assist in aerating the roots. proceeding. • Root barriers/root directors should be used as an aid to direct the spread of the root system and prevent damage to buildings, services and surfacing. Example of tree in hard surfacing
366 7.6 - Trees and Ornamental Planting Figure 7.26 – Tree pit detail with Greenleaf Arboresin porous tree pit surfacing (or equal approved)
367 7.6 - Trees and Ornamental Planting Figure 7.27 – Tree pit detail with Greenleaf Clyde Grille (or equal approved)
368 7.6 - Trees and Ornamental Planting Figure 7.28 – Tree pit detail with Jones of Oswestry Arborslot Grille (or equal approved)
369 7.6 - Trees and Ornamental Planting Ornamental Shrub and Perennial Planting Planting Design overcrowded. Herbaceous perennials are quicker Generally planting within the public realm should be to establish and can therefore be planted more cost Ornamental shrub and perennial planting should designed using simple bold, single species blocks, effectively using smaller pot sizes (e.g. 1 – 2L). The be carefully incorporated into the design of the city selected from a limited palette, which allows for use of higher densities when planting herbaceous centre public realm to maximise aesthetic benefits repetition of species to unify a space or define a perennials (inparticular) will help with weed without generating unsustainable maintenance route. The palettes of species chosen for any one suppression and also take into account potential requirements. As previously identified, it is planting scheme should provide year round interest, plant failures. suggested that ornamental shrub and perennial with a good proportion of evergreens creating planting would be appropriate in the following structure during the winter months. Planting Plant Defects Periods locations: design should exploit contrasts or similarities in The first three years following planting are critical. form, texture and colour to produce dramatic and The use of defects periods for implementation • City centre spaces and gateways; attractive visual displays. schemes will be essential to ensure that plant replacement occurs. • Streets in need of environmental improvement, Species but lacking space for tree planting; and All species selected must be suitably hardy and robust to ensure survival in the public realm. • Grosvenor Park and other greenspaces. In response to concerns about climate change consideration must also be given to the ability Siting of selected species to tolerate drought and/or As described within the Section 7.3 - Street waterlogged conditions. Species must be chosen Furniture, the preferred approach should be to for their overall decorative effect and seasonal provide permanent raised beds/planters only as an highlights. It is essential that plant species of the integral part of the design of new spaces within the right size are chosen for each particular location. public realm. Planting areas should not sit flush Growing requirements, particularly light tolerance with paving in busy pedestrian areas, but should be are an important consideration. The aim should be raised to prevent pedestrians walking across them. to design low maintenance schemes using plants that are suitable at their maximum height and will From time to time high quality portable planters therefore not require regular pruning. (see page 337) may be incorporated into schemes, where they are appropriate to the design of the Plant Sizes and Densities scheme and where there is a perceived need for As a general rule, shrubs are much slower growing them to be moved in the future to provide access or than herbaceous perennials and so in order to space for an event. achieve good structure and initial impact shrubs should be specified at a minimum size of 5L. Shrub densities will vary considerably depending on the species selected and must take into account mature size to ensure that shrubs do not become Chester in Bloom bedding display
370 7.6 - Trees and Ornamental Planting Annual Bedding Displays Grass areas Page 338 provides examples of the types of It is recommended that wherever possible, temporary planters and containers that are currently Grass areas can be particularly valuable as flexible ornamental shrub and perennial planting schemes and will continue to be used each year. As with seating and picnicking space during the summer are used to decorate the public realm. Although other items in the public realm, temporary planters months, as well as offering visual relief to hard these schemes have their own maintenance and other containers should be carefully located urban environments. These should be located to implications they represent a longer term so as not to obstruct pedestrian flow. The use of respect main pedestrian desire lines. Designing investment and more sustainable approach to hanging baskets fixed to existing columns will assist raised areas for grass can prevent unnecessary wear planting in comparison with annual bedding. The in minimising street clutter. and tear from foot traffic. Flush mowing strips opportunity to combine shrub and perennial should be added around trees and furniture for ease planting with annual planting highlights might also of maintenance. represent a less intensive, but effective approach.
Having said this, it is understood that ‘Chester in Bloom’ is valued by both residents and visitors and annual bedding does have a role to play in decorating some parts of the public realm and offering seasonal highlights. Last year’s ‘Chester in Bloom’ was developed using a cycling theme, which resulted in the creation of temporary living artworks that formed ‘talking points’ within the public realm. The use of an annual theme should continue and themes should be chosen through consultation with the local community. It is understood that the council are hoping to encourage greater community involvement in the future.
It is understood that the RHS are keen to work with the council to identify a palette of bedding plants considered appropriate for Chester. Seasonal planting schemes should vary their colour palettes annually to sustain interest. It is suggested that generally annual bedding displays should be focused on the main routes and spaces, offering focal points within the public realm. This will heighten impact rather than spreading the planting too thinly across the city. Example of raised grass area
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