Often, homeowners give little thought to the evergreens on their property. These reliable trees carry on without much maintenance, providing shade for homes and yards, giving shelter to wildlife and growing consistently year after year. Though a number of different theories exist on when and whether to fertilize evergreens, rely on a few basic strategies to keep your evergreen trees healthy and looking their best.
Most evergreens get sufficient nutrition from the soil and the plant matter that decomposes beneath the tree or shrub itself. If the evergreen is located near a lawn area, fertilizers from lawn care will generally be enough to help support the tree as well. If the tree is located away from the lawn, however, additional nitrogen may be needed to sustain new spring growth and to recover from stressful winter weather.
When To Fertilize
If you perform a soil test of the area around the root system of the tree, the test will tell you if the ground has sufficient phosphorus for good growth, according to the University of Minnesota's website. A complete fertilizer such as 10-8-6 is recommended if additional phosphorus is needed. Mid-April is a good time to fertilizer evergreens, to provide nutrition for the new growing season and to help recovery from winter stresses. Another feeding, if desired, can be done Aug. 1. Do not apply fertilizers after the ground has frozen.
Newly Transplanted Trees
Newly transplanted evergreens do not generally need fertilizing. Strong nitrogen fertilizers can, in fact, burn tender roots of trees that are attempting to re-establish. Do not place fertilizer into the holes for the new trees. Allow the trees to overwinter and then examine them carefully for signs of nutritional deficiency. Pale foliage or weakness in new growth are signs that fertilizer is needed.
A recommended maintenance rate for fertilizer is generally 2 to 4 pounds of nitrogen per every 1,000 square feet of soil surface. This is applied every two to four years for immature, fast-growing trees. Slower-growing mature trees may require only one pound of fertilizer. Apply this with a drop spreader and then water thoroughly to allow the fertilizer to leach deeply into the soil. You can also puncture holes into the ground, starting 1 1/2 feet away from the trunk, to a depth of 8 to 12 inches deep, spaced about 2 feet apart in concentric circles. Then, divide the fertilizer into equal amounts and place into the holes. Water the area generously.