In general, large evergreen trees can be treated the same as deciduous trees with respect to fertilizing. Evergreens normally have roots that extend beyond the branch spread. Compost incorporated before planting, used as mulch around trees and shrubs or applied to turf as a top-dressing can supply the nutrients required to keep trees and shrubs growing well. Most composts are also good sources of calcium, P, K and micronutrients. In addition to supplying plant nutrients, top-dressing or amending with compost also adds organic matter to the soil, thereby improving soil structure, water infiltration and microbial activity.
Bark mulches supply some calcium and potassium but are low in nitrogen and phosphorus.
Ideally, soil test results should be used to determine fertilization rates, especially for phosphorus, potassium and micronutrients. Certain plants such as broadleaf evergreens, dwarf conifers and alpine plants should receive about half the rate of most deciduous plants. Excessive fertilization of pines often creates large gaps between branch whorls. In general, surface application of fertilizer is an efficient and effective way of getting nutrients to tree and shrub roots. In many cases, fertilization of turf supplies enough nutrients to meet the needs of trees in the area.