Shade: Beat the heat with a tree

If you ever have thought a shade tree in the back yard would be nice then it's probably during the hot summer days like we are having now. A tree to dapple the strong sunshine, to provide some relief from the heat, a tree to sit under and read a book, for the kids to play under without getting sunburned.
A shade sail could provide the same sun protection, but it doesn't the same cooling effect. The mass of water stored in a tree - which travels from the soil into the roots, through the trunk and branches then evaporates out the leaves - provides a cooling effect that is unsurpassed.
During the winter months, when the last thing you want to do is block out the sun, a deciduous tree will have lost all its leaves allowing light to pass through.
In situations where you need the tree to also provide privacy from neighbours or remove an object from view then an evergreen may be a better choice.
There is a massive selection of trees that will provide excellent shade. The skill is to choose one that will meet your needs and requirements. Things to consider are:
What ultimate size you would like
What space is available
Do you want flowers too
Do you want good autumn foliage colour What are the practicalities of your site - soil type, exposure to wind, frost, cold, coastal etc.
A trip to Bason Botanic Reserve on Rapanui Rd shows some excellent examples of shade trees, including the deep rich, refreshing green of the Liquidambars and Liriodendrons (tulip tree), along with the spectacular yellow of the golden elms. These all are fairly big trees, great if you have room for them to grow.
For a smaller town section, consideration needs to be made of the shade a tree may create for a neighbour, so smaller-growing trees or those that respond well to pruning will be a better choice.
There are a number of different varieties of flowering cherry (Prunus) that all have slightly different growth habits, which means you can usually find one that will grow to the size you have available. Kanzan is a taller variety with spectacular double pink flowers that forms a vase-shaped head, while Pink Perfection has a similar flower but is far more spreading so forms a better shade tree if it's width you need. Jim's Delight is a relatively new release and reaches only 3m high. A real little gem if you want a small shade tree for a tight corner. It has spectacular single pink blossom in the early spring, as well as beautiful autumn foliage as the leaves turn shades of red and orange.
But the top-selling flowering cherry tree is Shimidsu Sakura. This has an excellent spreading umbrella habit. It will grow about 4m high by 5m wide and as well as an excellent shade tree for the summer it puts on a spectacular show in October with deep pink buds opening to double white flowers toned pink. Shimidsu Sakura also had a good display of autumn colours with leaves turning tones of orange and yellow before dropping.
Another excellent shade tree is the silk tree (Albizia julibrissin). In full flower at the moment. you will spot them around the city with their mass of fluffy pinky-red flowers covering the trees. Hotter summers, like we are having this year, seem to improve flowering. Silk trees have distinctive soft, ferny foliage which lends itself to dappled shade from its naturally spreading branches. These trees, if left to grow, will reach about 6m tall and 5m wide but are easily pruned much smaller. They grow quickly so good shade can be established in 3 to 4 years.
Driving around Hawkes Bay in mid-January I saw some magnificent jacarandas in flower with their cool blue-purple blooms.
Fruit trees can also make good shade trees. A plum tree at the bottom of the garden can make an excellent shade tree, with a mass of white blossom in the spring and then an abundant crop of fruit around Christmas. The added bonus is the fast growth rate of plum trees from which shade can be established as well as the ability that they can be pruned to size - so why not make your shade tree productive and choose a plum or another fruit tree?
We have talked about the beauty and good growth habits of flowering cherries. but you can also consider a fruiting cherry. The blossom isn't as spectacular but the bonus of growing your own cherries is worth weighing up.
Evergreen shade trees tend not to change through the seasons, and apart from flowers and sometimes berries, they will offer a very similar look year round. If you are wanting to use your shade tree as a screen to offer privacy then an evergreen tree will be a better option. A lot of the larger-growing native trees make spectacular shade trees - puriri, karaka, pohutukawa and titoki - but in a town section these will usually grow too big.
There are some good evergreen trees for smaller sections. Leptospermum Copper Sheen forms a good shade tree when its lower limbs are pruned. It has a lovely weeping habit with its coppery-burgundy red foliage making it an attractive tree. It also becomes covered in a mass of white flowers in summer. It is very quick growing and responds well to trimming. It can also be grown as a hedge.
Some Michelia varieties form lovely shade trees. I say "some", because there are varieties that simply don't grow large enough, and their habit is shrubby. However, the doltsopa variety and its hybrids form good evergreen trees. These form a trunk with a rounded head of branches and foliage that will offer good shade from the hot summer sun. A real feature of Michelias is an amazing display of highly fragrant, white flowers in the late winter and early spring.
¦Gareth Carter is general manager of Springvale Garden Centre.