Tree-planting myths

WASHINGTON - Many planting practices that were thought critical to the health of trees are simply myths. Some ideas that have long been accepted by experts have proven to be incorrect. This is understandable because it can take generations to comprehend the sophisticated systems of these magnificent plants. While you're enjoying the warm and cozy indoors this winter, let's examine some tree myths.

Myth 1: Newly planted trees need to be staked or guy-wired.

This is generally incorrect. Balled-and-burlapped and large-container trees are bottom-heavy, so they can stand on their own. Wiring them in place kills far more trees than it helps because in most cases the wires are never removed.

It's not staking and using guy wires that kill trees, but the lack of stewardship. This is a common problem, especially for street trees that are planted in holes and never given care again. Without removing stakes within one year of planting, and without enough water, trees die.

One exception to this rule is if you are planting a bare-root tree or one that is a poorly rooted plant from a container. In those situations, staking might be necessary.

Myth 2: When planting a tree, dig the hole twice as wide and twice as deep as the root ball, installing it so the tree trunk is planted at ground level and making sure you have properly prepared the soil.

Install root balls about 25 percent higher than ground level. Place the tree or shrub, and then fill the hole with a mixture of one-third compost and two-thirds native soil. Pack the soil mixture firmly so that any air pockets are filled in. Water the tree well, making sure the soil stays moist, but not wet, while the plant establishes itself, or until the ground freezes, if you've planted in fall or winter.

Research indicates that newly planted trees do best on a solid platform of soil. Planting trees and shrubs too deeply is a common mistake that can lead to killing the plant. Avoid allowing the root collar (the flare just above the point where the roots join the main trunk) to be covered with soil or mulch. The roots need moisture, but the bark and root collar need air. If you cover them with soil, the bark will rot, causing the same girdling effect as wire.

Myth 3: Newly planted trees should be "fed" regularly.

Trees don't eat. They absorb nutrients and can be fertilized in fall with a general-purpose dry fertilizer using a broadcast spreader over the surface of the root zone. Use a product with an analysis of about 10-6-4 (nitrogen-phosphorous-potash). Trees receive their nourishment through osmosis and need moisture to absorb these minerals through their cells. They require a balance of properly moist soil that has been prepared to allow enough air space for the roots to grow and absorb the minerals that the soil contains. Clay is loaded with minerals, and if it's mixed with enough organic matter, it will be easy for trees' roots to reach out and take what they need.

Myth 4: Trees need to be watered constantly.

Trees need to be watered when they need water - not before or after. This is not rocket science. Stick your finger in the soil and if it's dry, water. If it's moist, don't. Most plants do not like to be over-watered, and can die from constant watering.

Myth 5: Drought-tolerant trees don't need to be watered.

Yes they do, especially when they are becoming established. Xeriscaping - the practice of using native plants to minimize watering - doesn't mean not watering. A couple of trees that tolerate dry soils are paperbark maple (Acer griseum) and lacebark elm (Ulmus parvifolia). During establishment of trees, during the first couple of seasons, they still must be watered, but only when necessary.

Finally, one requirement that is not a myth is the most critical guideline to keep in mind. Before you plant even one tree, know what's below it. Have your utility lines located by calling 811, the federally mandated "call before you dig" phone number.

• Lerner is the author of "Anyone Can Landscape"(Ball 2001). Contact him through his Web site, www.gardenlerner.com. jml@gardenlerner.com