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Trees for the Ages
Trees dwell in our home landscapes the longest of all its plantings. The tree you plant today may grow for decades or even centuries.
Special Needs of Trees
Trees are long-term residents of our yards. Given 20 or 30 years’ time, an oak sapling with a rootball 12 inches (30 cm) wide often grows to 70 feet (21 m) high and wide. At maturity the root systems of such trees eventually cover an area about 210 feet (64 m) in diameter.
Key to growing these long-lived trees is starting with tree species well adapted to your site, soil type, light, exposure, climate, and other conditions [see Matching Sites to Trees and Shrubs].
Another must for growing healthy trees is to plant in soil of the type and texture of the soil that they will occupy at maturity.
Catalpa, scarlet oak, and sassafras thrive in heavy, slow-draining clay soils. Other trees, however, prefer loose, sandy soils that take up and release water quickly. They include arborvitae, red oak, and white pine.
Let’s review quickly the soils large landscape trees prefer [See: Soil for Trees and Shrubs.] Assume, for example, that you are planting a shade tree and your site consists of heavy clay soil.
Unless you plan to amend the entire site—at least 100 feet (30 m) in every direction—your sapling will do better in the long run you plant it right into that unamended clay soil. Do them a favor and skip soil improvements.
Extensive planting research shows that trees planted with only native soil in their planting holes perform better. They develop larger, better-established root systems than trees planted in a small area of heavily amended soil.
One soil additive you may wish to use is applying so-called mycorrhizal fungi—organisms that promote tree root development—or beneficial nematodes.
Most healthy soils naturally contain mycorrhizal fungi. Compacted soils may need supplements.
Some species of trees—such as citrus, almonds, or other nut and fruit trees—fall victim to harmful soil nematodes and die unless their soil is inoculated at time of planting with large numbers of good nematodes.
Both mycorrhizal and nematode cultures are available at many nurseries and from direct merchants.
Trees for New Homes
Planting trees in new housing developments are a special case. Many times, all the topsoil was removed from a new-home site before construction.
If you are landscaping on a site where only subsoil remains, consider bringing in new topsoil before planting your trees.
Topsoil is available at many materials yards and home improvement retailers. All you’ll need is the number of square feet to cover and the depth you wish to apply.
Fertilizing New Trees
After planting, apply slow-release fertilizer to the soil surface in a circular or donut-shaped pattern away from the tree’s trunk. Begin distributing fertilizer at the label-recommended rate, just outside the diameter of the root ball just planted, and continue for 12–18 in. (30–45 cm).
Organic choices for slow-release fertilizer include well-composted manure and natural compounds containing high phosphorus and potassium, but low nitrogen content. Synthetic slow-release fertilizers are formulated to release their nutrients over an extended period of time, and may be dry powder or granules.
Avoid feeding with high-nitrogen formulations that would cause growth spurts before roots are fully established.
Regardless of choice of fertilizer, work it into the top 4 in. (10 cm) of soil after application. Water it in to help carry it down to the roots.
For more details on early care and post-planting maintenance of trees and shrubs, see Establishing New Plantings.