Different trees are adapted to different soils, climate and other growing conditions. However, basic tree growing needs are similar from species to species.
Soil is perhaps the single most important variable in a tree's environment. Any tree will grow best in a soil that is at least three feet deep, allows water to percolate through it, but can retain adequate moisture for roots. A certain amount of decomposed wood or leaves, or organic matter, is desirable. An ideal acidity-alkalinity measure, called pH by soil scientists, is about 5 to 6. This is considered an acid soil by agricultural standards. The more the soil pH varies from these ideal standards, the fewer number of tree species that can grow in it. Trees planted in poor soils will grow slower and may have more problems than trees growing in better soils.
Moisture is closely related to soil quality, since well-drained, porous soils can provide more usable water to the roots. Trees consume large amounts of water, but at the same time roots need oxygen to breathe. Soils should provide adequate moisture and at the same time allow enough air exchange for oxygen to reach the roots. Very sandy or gravelly soils cannot hold sufficient water for some trees. Heavy, compacted soils with poor water percolation may hold too much water and cause roots to suffocate. A few trees are adapted to grow in wet and swampy sites, but most will decline in poorly drained soils.
Sunlight allows a tree's leaves to manufacture food in the form of sugar through photosynthesis. If tree foliage is shaded by other trees, buildings or other objects, the number of leaves and amount of food produced will be reduced. How much sunlight each tree needs to grow well varies with species. Some trees grow naturally as understory trees and tolerate shade well. All trees will have sparser foliage and fewer flowers at reduced light levels.
Some locations, especially with undisturbed, native soils, have the capacity to grow large, vigorous trees. In other places, trees may never be able to achieve acceptable growth. Trees in urban areas are troubled by growing conditions that are much less than ideal due to removal of topsoil, soil compaction, soil contamination, air pollution or lack of growing space. The more limitations on the growing site, the more carefully trees will need to be selected.
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