Gardening: Growing trees for shade in Whanganui

Strong trees provide great shade and can be appreciated in many Whanganui parks.

Gareth Carter is the general manager of Springvale Garden Centre in Whanganui.

OPINION

After a cold wet start to summer we are now getting some hot summer days.

Such days are perfect for picnicking and seeking the refreshing shade of a suitable tree.

Decent-sized, strong trees provide great shade and can be appreciated in many of our parks.

A trip out to Bason Botanic Gardens on Rapanui Rd shows some excellent examples of shade trees, the deep rich refreshing green of the Liquidambar and Liriodendron (tulip tree) are some of my favourites along with the spectacular yellow of the golden elms.

These all are fairly big trees which are great if you have lots of room for them to grow.

If you ever have thought a shade tree in the backyard 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 sunburnt.

You know that a shade sail could provide the same sun protection, but it does have not the same cooling effect of a tree.

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.

If you go for a deciduous tree as your selected shade tree, the tree will adjust to the light and warmth needs of winter.

During the winter months, when the last thing you want to do is block out the sun, a deciduous shade 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 great selection of trees that will provide excellent shade. The skill is to choose one that will meet the needs and requirements you want from it.

Things to consider are what size you would like, what space is available, would you like it to flower and would you like something with good autumn foliage colour for seasonal interest.

These need to combine along with the practical implications such as soil type, exposure to wind, frost, cold, coastal salt spray, etc, to ensure the tree’s successful growth.

For a smaller town section, consideration needs to be made of the shade a tree may create for a neighbour, so smaller growing or trees that respond well to pruning will make a better choice.

Flowering cherries (Prunus) are a very popular choice of shade tree.

There are a number of different varieties that all have slightly different growth habits.

This means if it’s a flowering cherry you want then you can usually find one that will grow to the size you have available.

Kanzan is a taller growing variety with spectacular double pink flowers and forms a vase-shaped head, while Pink Perfection has a very similar flower but its growth habit is far more spreading so forms a better shade tree if it’s width you need.

Jims Delight is a relatively new release and only reaches 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 spectacular autumn foliage as the leaves turn shades of red and orange.

A top-selling flowering cherry tree would be Shimidsu Sakura. This has an excellent spreading umbrella-shaped growth habit.

It will grow approximately 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 yellows before dropping.

Another excellent shade tree is the Silk Tree (Albizia julibrissin).

In flower at the moment, you will be able to spot them around the city with their mass of fluffy pinky-red flowers covering the trees.

Hotter summers seem to improve the flowering of these trees.

The silk trees have distinctively soft ferny foliage which lends itself to provide good dappled shade from its naturally spreading branches.

These trees, if left to grow, will reach approximately 6m tall and 5m wide but are easily pruned to a much smaller size. They grow quickly so good shade can be established in 3-4 years.

Driving around the city I have also seen some magnificent Jacarandas in flower with their cool bluely purple blooms. These too can be kept smaller with pruning.

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 springtime 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?

Other fruit trees that make good shade trees are cherries. we have talked about the beauty and good growth habits of flowering cherries, you can also consider a fruiting cherry.

The blossom isn’t as spectacular but the bonus of growing your own cherries is an option 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 year-round screen to offer privacy then a evergreen tree will be a better option for you.

A lot of the larger growing native trees make spectacular shade trees such as the puriri, karaka, pōhutukawa, and titoki but in a town section these will usually grow too big for the space available.

There are some good evergreen trees for smaller and town 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.

Very quick growing, it makes a good option for quickly establishing privacy.

It responds well to trimming and can also be grown as a hedge.

So if you are feeling the summer heat, then consider a good spot to plant a suitable shade tree.

Gareth Carter is General Manager of Springvale Garden Centre.