Evergreen trees and shrubs benefit from fertilizer applications and soil amendments that add nitrogen and enrich the nutrient value of the soil. Young evergreens will require fertilizer once or twice per year while healthy mature evergreens will need less fertilizer applied every other year or once per year at the most, if at all. Sub par growth or discolored foliage is a sign in mature evergreens that soil is in need of fertilizing.
Amend the soil around evergreens with organic fertilizer at planting time or top dress the surrounding soil every year or two with several pounds each of well aged manure and quality compost. Create an even layer starting 6-inches out from the trunk to out past the drip line of the evergreen and water in well.
Feed mature established evergreens once each year in the spring with a complete formula granular fertilizer such as a 10-8-6. Apply according to the package label directions but not exceeding 1 pound of fertilizer for every 500 square feet of soil area around the evergreen.
Feed young rapidly growing evergreens with the same 10-8-6 formula in the spring and again in the late summer or fall. Feed young evergreens at a higher rate not to exceed 2 pounds for every 500 square feet of soil area.
Water your evergreens regularly and deeply to supplement annual rainfall. Maintain evenly moist soil when reaching your finger an inch or two down into the soil. Do not let the soil become dry as the evergreen foliage can begin to brown which is irreversible.