The "Should nots" of Pruning

Winter is the best time to prune most trees and shrubs. When plants are dormant, removing twigs, stems and branches can be done without shock to the plant. Also, when done correctly, pruning can promote healthy spring growth.

Usually, I discuss proper pruning techniques in my column. However, it may be more beneficial to discuss incorrect ways of pruning. Knowing how not to prune often is often the more logical prerequisite in knowing how to prune!

In the case of palms, I see many trees around town that are being damaged by excessive pruning. Palms should never be pruned to look like "rooster tails". Palms with only the top three or four fronds remaining have been pruned excessively and improperly. Only the lower leaves, the ones which have turned brown or are yellowing should be removed. Correct pruning of palms is a "once a year" job, which is no more often than "rooster-tail" pruning. The difference is that correct pruning keeps palms healthy, and looking their best. If your tree trimmer is "rooster-tailing", just say no!

Trees are also excessively pruned. In it's various forms, all excessive pruning is bad. But probably the most common form of abuse is what I call "limbing-up". This involves the removal of lower branches often for no apparent reason. In fact, on many trees, the entire lower half or even two-thirds of the branches are removed. Also referred to as "skirting", this practice removes important food producing limbs, and in the process weakens the trunk and roots, causes excessive wounding, and permanently disfigures the tree.

Once branches are removed, they can never be replaced, and they will not regrow! Most desert trees are naturally low branched and multiple-trunked. Forcing a palo verde or desert willow to look like a tall, single-trunked sugar maple from "back home" just doesn't work. Only remove lower branches if they are dead or dying, an obstruction, or safety concern. Branching does not have to be even all the way around a tree. If you must remove a lower limb on one side of the tree, do not try to balance it by removing limbs on the other side. Limit your branch removal to only what is absolutely necessary.

Just as "limbing-up" is the wrong way to prune, so to is "limbing-back". This is when large limbs are arbitrarily cut back. Large stubs remain after this form of severe pruning. In time, these branch stubs will rot, and the decay will move into the main trunk. As the decay progresses, the tree becomes structurally unsound and in danger of falling in a wind storm. Cutting large branches should only be done by a certified arborist who knows the correct procedures of "drop-crotch" pruning. This method, used for thinning and height reduction, does not leave stubs and other large open wounds.

When it comes to pruning shrubs, throw away the hedge shears! Shaping shrubs like Texas ranger and desert cassia into round balls destroys their shape and blooming potential. More importantly, shearing causes the lower part of the shrub to become bare and twiggy. Eventually only the top of the plant is crowned with leaves. Only rows of formal hedges should be sheared, not individual shrubs. If shrubs need to be pruned for size control, then selective cuting back and removal of the longer branches is advised. Removing them will maintain or reduce the size of the shrub while preserving it's natural form.

Finally, if your in doubt about whether or not to prune a tree or shrub, then you probably shouldn't. Use the time you would have spent on unnecessary pruning and have some fun looking through this year's spring gardening catalogs.

If you want to learn more about the correct pruning of desert plants, I highly recommend "Pruning, Planting & Care", by Eric A. Johnson. It is a guide to pruning plants of the Arid West, with lots of color photography and step by step instructions. It can be purchased at many local book stores.