Spring is tree-planting time for many gardeners. It's also the time to make big mistakes when planting. Alas, this tree popped out of it's planting hole due to poorly-trained landscape contractors after being struck by a car. This poor tree needed to get its roots away from the planting hole. (You can see the circling roots just the way they were in the planting container.) Planting on a mound will help "drive" roots away from the tree's base as it drys out faster, making the roots seek moisture further from the trunk. So will fracturing the sides of the hole. (This tree may have been "planted" by auguring a hole in the ground and just plopping the tree into the hole.) The roots responsible for absorbing water and nutrients are the very young and tiny root hairs found near the tips of new roots. Older roots, much like older branches, have a bark-like covering that protects the root but doesn’t produce root hairs. In one study done with radioactive isotopes in England, the roots 4.5 feet away from the trunk of a 10-year-old apple tree absorbed less than 10% of the water and nutrients absorbed by the entire root system. The study showed that proportionately, many more feeding roots are found at, or beyond, the drip line of a tree’s foliage. Because of this, I prefer to place a ring of in-line emitter tubing at or beyond the tree’s drip line. This produces a “doughnut” of moisture, and far more of the root zone is adequately irrigated than with a single line of hose down a row of trees. As the tree grows, extra lengths are added to this circle of moisture to correspond with the new growth in the canopy. By setting the circle of emitters farther out every few years, you’re encouraging the tree’s roots to explore more soil volume and gather more nutrients for superior growth. Such trees would stand a better chance against wayward cars.
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