When pruning, take care not to make common mistakes

Now is the time to prune most trees and shrubs. Plants are dormant, and you can see more what to nip and save. When done correctly, pruning promotes healthy growth.

Usually, I go over proper pruning techniques in programs, but it might be more beneficial to write about incorrect ways of pruning. Knowing how not to prune may be more logical than knowing how to prune.

Probably the most common form of abuse is removing too many lower branches. These branches become important food-producing limbs. Removing them weakens trees, causes excessive wounding and permanently disfigures them.

Once you remove branches, they are gone. Most desert trees naturally produce lower branches and multiple trunks. Trying to force a palo verde or desert willow to look like a tall, single-trunked sycamore from "back home" just won't work. Only remove lower branches if they are dead, dying or for safety reasons.

Branching does not have to be even all the way around a tree. If you remove a lower limb on one side of a tree, you don't need to balance it by removing limbs on the other side. Remove only what's absolutely necessary.

Just as removing lower branches is wrong, so is severely cutting back large limbs and leaving stubs. In time, these stubs rot, and decay moves into the main trunk. We are now seeing this killing fruitless mulberry trees.

If you must remove large limbs, call in a certified arborist who knows the correct procedures of "drop-crotch" pruning. This expert uses thinning and height reduction that does not leave stubs or large open wounds.

When pruning shrubs, lock up the hedge shears, including those of your gardener. Shaping shrubs such as Texas ranger and desert cassia into round balls destroys their shape and, even more significantly, their blooming potential. Shearing also exposes the shrubs' lower branches, something you don't want, because the plants' leaves become smaller and you get fewer flowers. If shrubs need severe pruning, cut back only those extending branches down inside where they attach to a main branch to preserve its natural form.

If you are in doubt about pruning desert trees or shrubs, don't do it.

To learn more about correct pruning of desert plants, Eric A. Johnson's "Pruning, Planting & Care" (Ironwood Press), guides you step by step in pruning plants in our climate. It is a must in my library. You should be able to find it at local bookstores.

Fruit trees need precise pruning. It stimulates growth, improves structure, encourages larger fruit size, keeps trees controllable for easier harvest and becomes more attractive in your yard.

Here are some tips to ensure success:

• Prune annually. If you wait until next year, pruning becomes more difficult when removing older growth.

• Remove all broken, dead, dying or diseased wood. Make cuts back beyond the point of infections to get it all.

• Never let limbs touch each other. Take the one cluttering the tree most.

• If two limbs run parallel, eliminate one; the top limb shades the lower, so it won't produce fruit.

• When removing a limb, cut it back to where it attaches to the primary limb.

• Do away with branches that grow through the center of the tree. If left, they ultimately damage other branches and potential fruit.

• Trim tips off last year's growth to a height suitable so you don't have to climb a ladder to get fruit. This cut stimulates new growth from those tips.

• Remove water sprouts growing straight up from older branches. They won't produce fruit, so eliminate them when they appear. They'll be harder to remove next year.

• Remove suckers coming up from the rootstock when they are first noticed. They rob energy and reduce nutrients for fruiting buds and, even worse, can eventually consume the tree.

• When pruning large, overgrown trees, never remove more than one-third of the branches in a given year. Once gone, examine the tree from a distance to assess its shape and form, trying to imagine what it will look like if you removed more.

• Finally, never cover wounds with pruning paint. Studies find this practice provides an environment for pathogens to flourish. Let the tree heal itself.

Linn Mills writes a gardening column each Sunday. You can reach him at linn.mills@springspreserve.org or call him at 822-7754.