Trees have always provided us with fuel, lumber, food, recreation, beauty, and shade. They fight air pollution, dampen noise, reduce home heating and air conditioning costs, control soil erosion, and provide shelter for all kinds of wildlife. They help make our urban and suburban spaces more livable. As popular concern about the “greenhouse effect” continues to mount, so does appreciation of the importance of trees to the home landscape.
In this file we make a large distinction between large mature trees and trees that are less than 5 or 6 years old. We assume the only practical thing you can do for your large trees is to mulch them and sometimes water them. Pruning and fertilizing large trees is the province of professional arborists and we believe should not be tried by untrained homeowners. Therefore this file primarily discusses what you can do for the smaller and younger trees on your property. It includes basic tree care tasks such as feeding, watering, and mulching, that you can easily perform yourself.
While you don’t need to become a botanist or a professional arborist to care for the trees on your property, there are a few facts that might be helpful in your efforts to have healthy trees all year round, year and year. Most trees have two sets of roots. The deep roots are designed to give the tree stability and they are the ones looking for water. The second set is the roots you need to know about. They are generally shallow anywhere from 4 to 12 inches deep. These are the roots searching for food and again for water. The feeder roots of a five foot tree may have a diameter of only three or four feet, however when that tree becomes mature, that root system can travel out as far as twice the distance from the trunk to the drip line.
So whether you are feeding, watering, or mulching that tree, you see that working just a few feet away from the trunk does not do the job. These feeder roots function best, as with all other plants, when the surrounding soil has lots of organic matter in it (from 3 to 5%). That is why we recommend that you either mulch the tree or grow ground cover under the tree as far out from the trunk towards the drip line as your aesthetic tolerance will allow. Ideally all trees will have ground cover or mulch all the way out to the drip line, but in some case that might mean you don’t have any lawn left. In the end though it is a compromise decision of the looks of the yard over the long-term health of the trees.