SELECTING WOODY PLANTS 

Woody plants include trees, shrubs and many lower-growing plants.  What to look for when choosing a woody plant:

  • How tall will it grow? The stated height on plant labels are guidelines, not hard and fast rules – often trees will grow considerably taller or smaller.
  • How dense? The denser the crown, the better its shade provision.
  • How wide? Broad-canopied trees need lots of space but they provide excellent shade compared to narrow, columnar trees. Some low growing shrubs are wider than they are high.  
  • How low does the foliage grow? If the foliage grows low to the ground, it may take up to much space, or you may have to spend time pruning back branches to provide good access beneath the tree.
  • Does it cause root problems? Think about nearby drainage pipes, foundations, paths, etc
  • Is it hardy? Does it have good resistance to stress, pests and diseases?
  • Does it drop leaves, branches, fruit, sap/resin or cones? All woody plants drop leaves, but some drop them all at once in autumn (deciduous trees), and although they make a huge mess, at least it’s all over and done within a few weeks (and you have the bonus of a pile of leaves for composting and mulching). Others continually drop messy leaves throughout the year.  Some can be quite hazardous in small backyards, dropping whole branches, pine cones or large and messy fruits. Some plants, particularly some conifers, will drop resins or sap that can be sticky or difficult to remove, or even damage some surfaces such as painted areas, or car enamel.
  • Does it pose a safety or health risk, such as having thorns, cause allergies, have irritating sap, or dropping branches. 

TREES

Trees are an effective way to create a cool, comfortable garden.  As hot air flows through the tree, the temperature drops as moisture evaporates from the trees foliage, and oxygen levels rise.  

After you’ve made sure the tree won’t be in the way of paths, the driveway, buildings or a clothing line, and that it won’t interfere with underground drainage pipes or overhead wires, think about how it can be best positioned for maximum summer shade effect. 
Planting a tree on the northern side of the house (or the southern side if you are in the northern hemisphere) will shade the interior rooms for much of the day; a tree on the western side will shade the house and garden when it’s generally most needed - the afternoon.  

DECIDUOUS OR SEMI DECIDUOUS TREES

Many deciduous trees provide shade in summer and allow sunlight through during winter. Though these trees tend to occur mostly in temperate or even colder regions, there are some tropical trees which are deciduous or semi deciduous. Good examples are:

  • Acer negundo (Ghost Maple) – An hardy, fast growing tree to 6-12m tall. The cultivar A. negundo ‘Aureo-marginatum' grows to 5-6m tall, and has attractive yellow edged leaves. The cultivar A. negundo ‘Variegatum’ grows to 5-6m tall, has very attractive white margined leaves. Any non-variegated shoots should be removed as soon as they appear for these two cultivars. 
  • Acer palmatum (Japanese Maple) – A lovely small tree for the garden. Grows up to 6-8 m tall. Many varieties are available that display different leaf colours and shapes. Autumn foliage is best in cool areas in full sun. It has a fibrous root system that rarely causes problems.  
  • Bauhinia variegata – A small tree reaching 5-10 m. Large orchid-like white or mauve flowers in early spring. It may need shaping to develop a tree-like form. It grows in many parts of Australia, but is only fully deciduous in cold areas. 
  • Calodendrum capense (Cape Chestnut) – Grows to 8-15 m with a broad crown. Profuse clusters of pink flowers in mid to late spring. Fully deciduous in cooler climates and areas with dry winters; evergreen elsewhere. 
  • Caesalpinea ferea (Leopard Tree) - Medium sized tree to 6m with leopard-patterned bark. Showy yellows blossoms appear in spring. Best in Tropical and subtropical areas.
  • Caesalpinia pulcherrima (Pride of Barbados) – A medium shrub to small tree (up to 4 m). It has attractive red and yellow flowers in summer and autumn, and has fern-like foliage. It needs pruning in its early years to shape it into a tree form. A good shade tree for small gardens in frost-free areas (tropics and subtropics).
  • Delonix regia (Poinciana) – Grows to 10 m tall but has a much broader spread. It has bright red flowers in late spring. It has an attractive broad canopy so it need lots of space to spread. An excellent shade tree for subtropical and tropical areas only. 
  • Fraxinus excelsior ‘Aurea’ (Golden Ash) – Grows to 6-12m tall, with its spring and autumn foliage being golden yellow. It is also attractive in winter when it’s yellow-gold younger branches can be easily seen. Lower side shoots should be removed as they appear to promote a tree-like shape when the plant is young. A pendulous form is also available, and this is grafted onto seedling root stocks at a suitable height.
  • Fraxinus oxycarpa (Desert Ash) – Grows to 10-15m tall, and is fast growing, and generally hardy in hot, dry conditions. Superior forms budded on to seedling root stocks are available. 
  • Jacaranda mimosifolia – Grows 10-15 m tall and has a broad crown. Showy mauve bell-shaped flowers in spring and fern-like leaves throughout summer. Fully deciduous in cool to mild areas; retains some foliage in warm climates. 
  • Koelreuteria paniculata (Golden Rain Tree) - Fast growing and hardy tree to 12 m with a broad canopy. Small yellow flowers are produced in panicles in late summer followed by inflated red capsules through to autumn. Quercus sp. (Oaks) – Tall trees which are best suited to larger gardens. Good autumn display in cool climates (especially the Pin Oak, Quercus palustris). Tolerates warm, hot summers but needs cool winters.  
  • Robinia pseudoacacia (Golden Robinia) – Grows to 10 m tall and 8 m wide. Can be fast growing in good conditions. Attractive lime-green foliage turns golden in autumn. Roots can be a problem.
  • Tabebuia sp. (Trumpet trees) - Grow around the 6-12m height range with a number of different species well suited to the subtropics. Colours of flowers are either yellow, pink or mauve in clusters during spring or summer. Most are attractive shaped trees.
  • Liquidambar styraciflua – Tall pyramid or columnar-shaped tree growing 20-30m tall and 6-8m wide. Good autumn display in cooler climates. Needs good summer rainfall.

 

EVERGREEN TREES

The advantage of evergreen trees is to provide year-round shade. This may be a disadvantage in colder climates because they create greater darkness over winter; but for a hot climate, where the sun can create excessive glare as well as heat; it can be advantageous to grow more evergreens. 

WOODY FLOWERING SHRUBS 

There are many different shrubs that flower at different times throughout the year.  Other shrubs provide year-round foliage interest.  
Many of the smaller shrubs, growing 1 metre or less, are particularly showy.  Fuchsias, gardenias, many azalea cultivars, roses, geraniums and hydrangeas are just some of the smaller shrubs that have long flowering periods. These shrubs are especially useful in gardens with limited space and will grow well in pots. They’re also useful as fillers, planted in the gaps between larger shrubs, and some are ideal as fast-growing low hedges, or just as specimen flowering plants.  
Medium and large sized shrubs often form the bulk of plantings in larger gardens.  They’re a useful size for screens and hedges, and for general background greenery.

SELECTING FLOWERING SHRUBS

  • Choose plants that flower when you want a display.  For example, many roses may flower from spring to autumn, but often produce their best flowers in spring. 
  • Choose plants that suit your garden conditions. For example, if you are near the coast choose plants that are wind, salt and sun tolerant; if you are live in a dry arid zone choose plants that are tolerant of drought and sun.
  • Choose plants that fit with other plants in the garden, not just in flower colour but also in their foliage and form. 
  • Choose plants that can be easily maintained by clipping or pruning. Clipping extends the life of many of these plants, maintaining their shape, and encouraging new growth, which produces the next season’s flowers.
  • Unless you have plenty of room, avoid plants that spread (eg. suckers, self layering).
  • Think about the plant’s longevity – some small shrubs grow rapidly and are ideal for a quick display, but may die after a couple of seasons.  
 

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