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7. Ask a Desert Gardener, Dec 2023


December is the coldest month in Las Vegas.  Although daytime temperatures can be quite moderate, evening temperatures can dip down to the low 30’s or below! There are preventative measures to protect your landscapes from cold damage as well as preparing your gardens for the Spring.

Inspect your irrigation systems making certain that the narrow tubing is buried at least 2” below the ground to prevent freezing, splitting and leaks.  Check the underground irrigation boxes for frozen valves and make sure you have placed insulated covers over exposed spigots and pipes. Close down fountains and other “water features” that may freeze.

December is a good time to replenish both rock and organic mulch in order to protect soil and roots from freezing. Once leaves have fallen off deciduous trees and bushes, remove any remaining rubbish from you landscape to prevent unwanted rodents and insects from building nests.

Any remaining pruning should be completed. Wait until Mid-December for “late” blooming plants to go dormant before heavily pruning. At that time, 1/3 of the tops and side branches of roses should be removed and lantana and lavender plants should be pruned down to soil level. Heavy pruning of Texas Rangers, Jasmines and Hawthornes will stimulate fresh growth and flowering once the growing season begins.

Follow the Water Authority Winter Schedule for “once a week” irrigation. Remember, however, NOT to water after the sun goes down or when ground temperatures approach freezing. Succulents should NOT be watered at all during December through January.

Cold sensitive plants can be wrapped with burlap while young plants can be protected by placing Styrofoam cups over their tops to insulate them from cold and wind damage. Plants can also be protected by wrapping them with outdoor (non-LED) Christmas lights that can be turned on during cold winter nights. An old blanket can be thrown over delicate bushes when temperatures go below freezing.

Potted plants should be moved close to the outer walls of your home to take advantage of the sun’s reflected heat. During prolonged cold spells, move these pots into your garage.

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Howard Galin is a University of Nevada certified Master Gardener and the Chair of the SCA Garden Club House Call Program.