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Trees and Shrubs

Posted 1/13/2016

Trees and shrubs bedecked with foliage and flowers provide some of the most wonderful views in our landscapes. Since we are well aware that the Mojave Desert is not a particularly green space, we can appreciate the visual relief these woody plants can offer from the spectacular reds and browns of native lands. If we obtain fruit from them, then we are even more fortunate nothing could be more refreshing than a ripe nectarine, juicy in late spring. Those trees that are large enough can provide welcome shade from the relentless sun, especially in midsummer.

For these reasons, some gardeners can become melancholy in winter, with all the starkly naked limbs of the deciduous trees we enjoy for their green canopies. Perhaps there is an open seedpod or dried fruit on a high branch, making it an even more lonesome sight.

This time of year is not all gloom, despite bare trees, cold weather and the passing of the festive holiday season. Now is the time when we can see how the wood, the skeletons of our trees, is faring. This is when we can examine their structure and make some necessary changes before they burst into leaf in a few months.

In this dormant state, they can tolerate some heavier pruning than they could if the sap were running.

Leafless trees in winter display any problems they might have developed over the previous several months, and this is the time to pay attention to them.

Take a look at that woody frame for branches that have broken or are rubbing against each other. Those can be open wounds, which provide an avenue for insects and disease organisms to enter. These may cause further injury, even death, so they need to be removed.

Once any damaged parts are gone, the tree's structure is more apparent. It is best if its architecture is well balanced, with limbs evenly spaced around the trunk. Too many branches on one side or the other is less attractive, and results in a greater likelihood of sunscald on the unprotected side. There should also be roughly equal spaces between branches as they grow up. If the upper part has more than the lower, it can look top heavy. If the lower part is much denser, it can look unhealthy.

It is the gardener's decision: what do you want it to look like, and can you do your own pruning? If heavy pruning is necessary, or you would need a ladder, consider hiring a certified arborist. They are experts and worth hiring.

Even some shrubs that have not lost all their leaves can receive pruning. This is NOT the time to prune anything that flowers in early spring; those should wait until just after they finish blooming. Cassias and Lady Banks roses should wait. Shrubs like lantana and Texas Ranger, on the other hand, benefit from a good grooming around now. A colleague and I have produced a fact sheet on pruning shrubs in the desert; call the Extension office for information.

Dr. Angela O'Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.

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