Deciduous Trees and Shrubs:
At this time of year, those deciduous trees and shrubs that lose all their leaves at once are most noticeable. For example, liquidamber has leaves that are very intense red in late autumn. It forms a strong contrast to the greens of the native trees, and provides a focal point of the garden.
Most of our natives are evergreen, apart from some exceptions such as ribbonwood.
Deciduous trees come from the colder climates of the northern hemisphere. They form the intense reds, yellows, oranges and purples as the green chlorophyll in the leaves breaks down prior to leaf drop. These other bright pigments then become obvious. The colour intensity is heightened where there is a big difference between day and night temperatures. This is why you can see more intense leaf colour in places like Upper Hutt, than say Wellington central.
I don’t recommend using deciduous trees to clients who live in very windy sites, or where they are near the coast. The strong winds tend to damage the leaves, especially in the early spring as the leaves emerge. Coastal winds commonly cause leaf scorch. You may however create a sheltered environment on an exposed site where you can grow these trees. Choose hardy shelter plants like natives trees to create shelter.
One of the more hardy deciduous trees is silver birch. This tree has white bark with black markings, and a graceful, weeping habit. The leaves go yellow in autumn. It will tolerate a reasonably strong non-coastal wind.
Two deciduous trees you are likely to see as street trees in Lower Hutt are liquidamber and golden elm. Liquidamber has maple-like leaves which turn red as mentioned above. The golden elm has rich golden-yellow leaves from spring to autumn. You need to be careful to choose non-suckering elms. Some of the elms such as the English elm produce a mass of suckers throughout your garden. In one large garden in the Wairarapa that I visited recently, it was a major problem.
One of my favourite trees is the copper beech, with its copper-red leaves. These trees need adequate room to grow, so are more appropriate for parks
Deciduous magnolias do not produce autumn leaf colour, but produce showy flowers in late winter to early spring on bare branches. Magnolia campbellii requires a lot of room to grow, while Magnolia stellata is ideal for smaller gardens.
Flowering varieties of fruiting plants include flowering cherries, the weeping silver pear and flowering crab trees. It is better to plant flowering cherries in more sheltered spots, otherwise strong winds remove most of the spectacular blooms in spring.
Deciduous shrubs such as hydrangeas produce blooms over summer, but hold their blooms until autumn. The flowers turn blue in acid soils, and pink in alkaline soils. You can turn your hydrangeas blue by adding aluminium sulphate, and pink by adding lime. I have just pruned my hydrangeas back, by pruning back flowering stems to a lower bud. I prefer to prune hydrangeas lightly.
Other deciduous shrubs suitable for sheltered gardens are spiraea, and the scented lilacs.
Mix you deciduous plants with evergreen ones, so that your garden isn’t too bare in winter. This also applies to deciduous plants like bulbs or hostas. While the leaves all dropping at once can be a nuisance, use these leaves in your compost heap, or leave them to contribute to the formation of humus in your soil.
Enjoy natures seasons!