Trees that grow in nature are fed through the leaves that fall and decay around them. These leaves also preserve moisture in the soil. On a lawn, the tree competes with grass for moisture and food, and the gardener will rake up fallen leaves to create a clean lawn and prevent grass disease. Therefore it is important to supply nutrients to the tree every 2-3 years, when the ground is workable, typically the spring or fall.
The most productive way to feed the tree is to strip the soil from an area all around the tree extending at least 2 to 3 feet beyond the outer branches, since the roof system extends this far. Apply stable or barnyard manure to this area, spreading it 3 inches thick and digging it in. Rake the soil back on the manure and level it, then return the sod. This is the most difficult method, but is best for feeding the tree.
Another method, much easier, is to drill holes over the same area, 12 to 18 inches deep and spaced about 15 inches apart. Each hole should be filled with a commercial fertilizer of bone meal, tankage, peat moss, or humus, along with chemicals, in a formula containing 10% nitrogen, 6% phosphoric acid and 4% potash.
Water and Trees
Lawn and specimen trees should be watered every 10 days, especially in the summer, when the heat causes trees to transpire even more water than other seasons. The roots of the trees are very deep so a light watering won't do. The hose or sprinkler should be used for at least an hour, and hard soil will need to be loosened.
It is a good idea to drive or bore a number of 1½ inch holes that are 3 to 5 inches deep and 3 feet apart, below the outer branches of very large trees. Place a canvas hose or cover the hose with a gunny sack and let the water run. New trees or small trees are watered best if you put a few pieces of drain tile in the hole and put the hose in these, allowing the water to reach the subsoil. Cover the drain-tile holes with stones to avoid evaporation.
Tips on Caring for Trees
Trees can be affected if their feeding roots are unable to get food, for example if a fill of soil is laid over their roots, or if a terrace of blacktop is laid over their feeding roots. Large, valuable trees are best protected by adding drain tile so that they will get water and air. The bark needs protection from dirt or fills directly against it. You can buy metal tree wells, 3 to 7 feet across and 1 to 3 feet high, or build a masonry wall.
Cap the wall with a circle of bricks or create a low wall to make an extra seat on the terrace. If you have some surface other than sod or earth around the tree, make sure it does not extend as far as the tree's outer feeding roots, and leave a circle of natural soil around the trunk. Care for your trees as injuries occur rather than wait to call in a tree surgeon and allow a weakened spot to remain untreated.
Any dead, decayed, diseased or injured bark should be removed by removing the entire limb. On a large limb or trunk, dig out the decayed matter, sterilizing and waterproofing the cut surfaces with creosote and liquid tar. White lead or paint should not be used as they will not seal when used on damp surfaces. Fill deep wounds with concrete. Use a pruning hook carefully, avoiding bruises.
