Late winter pruning
Between now and the beginning of February is the time for grooming woody plants. This part of spring preparation will make a big difference, not only for flowering and fruiting plants, but also for shade trees. When these plants have dropped their leaves, it is much easier to see their structure. Once that is visible, the intrepid Mojave gardener can see what she or he should do to make them grow better. A visual examination is important before making any cuts.
Since leaves are gone, the bare branches display any problems that require attention. Are any of them broken? A strong wind can do damage that might not be apparent under all the foliage. It is a good idea to look for breaks or cracks in branches and remove them before they become an avenue for pests to invade.
Without broken branches, the tree or shrub will look better immediately, but taking a few more steps will improve it even more. Are any twigs or branches rubbing against each other? Although it might not seem to be a big issue, but when they rub, they are abrading their tender bark. This scraping can leave a wound that could get infected with disease organisms or infested with insects.
If there is any indication that insect pests have invaded, or there is evidence of a disease, it is important to remove the affected tissue. If this is necessary, it is critical to sterilize the cutter after every cut — pruner, lopper or saw — using bleach or some other disinfecting solution. Otherwise, it is possible to spread the ailment from the unhealthy one to other, healthy ones.
Not everything will get an advantage from winter pruning, for instance a shrub that flowers early in the spring. These blossoms appear on wood that the plant produced last year. If you cut it off these branches, you are removing the flower buds. Prune early flowering shrubs (cassia, Banks rose, e.g.) soon after the blooms have passed. Anything that flowers later in the season (Texas Ranger, lantana) can benefit from grooming around this time. Ideally, a shrub should not look as if it has been cut at all, only that its natural shape is tidier.
There are several rules of pruning, but one of the most important is: never "top" a tree. This is the terrible practice trying to lower a canopy by chopping branches without paying attention to its natural shape. It leaves stubs that are unsightly and may even weaken the tree. This is similar to hedging shrubs or shaving them into unnatural balls or squares.
If a pruning job is particularly large, or would require using power tools, it is a better idea to use a certified arborist. A certified arborist has taken many hours of classroom education and practical experience. They have passed the Division of Forestry examination. They know how and what to prune, and will do it in a way that benefits the tree. They have also had a good deal of safety training, which is not the case with many home gardeners.
Dr. Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact email@example.com or 702-257-5581.