Guidelines | Thinning out trees and shrubs | Specific spacing rules
How far apart and how many plants should occupy any particular piece of ground is a difficult question to answer. Much will depend on the eventual size and shape of the tree or shrub and its rate of growth. The rate of growth of trees and shrubs depends greatly on soil conditions and, to a considerable extent, it is a matter of taste and experience.
Shrubs filling their allotted space
Dense planting fills the space quickly, hiding the soil and helping to control weeds. But, planting at close spacing is expensive, because a greater number plants is used. After a while, trees and shrubs planted too closely together begin to interfere with each other’s development and they all end up spoiled.
Thinning out trees and shrubs
The spacing guidelines might give a planting that looks sparse, but this will not last long. To avoid an initial sparse look, over-planting and subsequent thinning might be carried out. Quick-growing shrubs can be used as colourful, but temporary, fillers. Broom, cistus, escallonia, weigela, ceanothus and lavatera are examples. Some of these are short-lived anyway, so thinning is almost automatic as they reach their lifespan and die out.
Planting may initially look a little bare
Specific spacing rules
When planting near boundary walls, keep large trees about three metres away and plant small trees and shrubs the height of the wall away. Plant wall shrubs and climbers between 15 centimetres and 45 centimetres away. When planting near a house, keep large trees at a distance equal to half their eventual height plus 6 metres. Plant small trees and large shrubs no closer then 3 metres, unless they are of narrow, columnar shape.