Choosing a tree is without a doubt the most serious decision that a gardener, professional or amateur, has to make, for no other garden element has such far-reaching and long-standing consequences. This applies all the more when it comes to choosing a shade tree, as the right choice can significantly enhance the quality of the family’s life, while a poor one is liable to dramatically detract from it. Here are the critical points to remember.
It may be stating the obvious, but judging by the number of cardinal errors that one still sees today, it is necessary to ram this point home. It is imperative to undertake some research and determine whether the chosen species develops an aggressive root system. Trees like Ficus, Poplar, Casaurina, Erythrina, and Ulmus should not be planted within 20 meters of the house. If the future tree is intended to provide shade for a seating area, then make sure it will be planted a similar distance from underground sewage pipes. For example, the spectacular Delonix regia, (suitable only for warm winter climates) with its squat, umbrella form, might be wonderful to create a shady corner at the garden’s edge, but by virtue of its invasive roots, dangerous close to a building.
This is a critical question as far as energy consumption is concerned especially in hot, dry and Mediterranean climates. Ideally, the tree ought to be deciduous, (bare of leaves during the winter) because the shade provided in the summer significantly reduces the use of air conditioners, while the bare condition of the tree in the winter allows the sun to sufficiently warm the house thereby reducing the need for heating. Examples of appropriate trees for shading a house are hackberry, (Celtis) Judas tree(Cercis siliquastrum) and for small homes, the Crape Myrtle. (Lagerstroemia indica)
It is important to choose a tree that is appropriate in scale with the house. A massive Eucalyptus not only looks out of place next to a one story building, but by dwarfing it, is liable to induce a feeling of insignificance and claustrophobia amongst the home dwellers. The dark and gloom caused by excessive shade can similarly be a factor behind depression. The possible psychological consequences of these matters should not be under-estimated. For further discussion on this topic, go to the link below and then on the Articles page, arranged alphabetically, and find the article “Planting Trees – Where To Place Landscape And Fruit Trees.”
In principle of course, most people are interested in a species that will provide shade as quickly as possible. Admittedly, a great but slow-growing tree such as Pistacia atlantica, by taking about 20 years to reach 5-6 meters, would hardly be a suitable candidate. On the other hand, beware of many fast growing species. The very fast growers, like Tipuana tipu, require frequent and none to easy pruning for the first 10 years or so after planting. The question needs to be asked therefore, if the resources will be available for a difficult and expensive maintenance regime in the future.