As we approach the end of the year, I have been keeping an eye on our total annual precipitation for 2018. It’s not good. We normally average between 14 and 15 inches per annum. We are currently sitting at 8.5 inches. If my math is correct, that is about 40 percent less.
Semi-arid regions, such as Broomfield, typically receive between 10 and 20 inches per year. Arid areas average five to 10 inches each year. Our precipitation this year likens us to Phoenix, Arizona. We are dry. Very dry.
The effects of receiving below-normal precipitation for the past several years is easily visible in our landscapes. The aspens, blue spruce and pine trees in my own yard started looking sad in the middle of July. Even though I regularly water them, it still doesn’t seem to be enough.
This winter we need to pay particular attention to the lack of moisture and its effects on our yards. Colorado State University Extension has a fact sheet with some helpful information. CSUE shares that trees, shrubs, perennials, and even our lawns, can be damaged without supplemental water during the long dry periods from October through March: extension.colostate.edu/topic-areas/yard-garden/fall-and-winter-watering-7-211 .
Woody plants with shallow root systems are more susceptible to damage. This would include some of the deciduous trees like birches, maples, lindens, dogwoods and ashes. Evergreens, such as spruce, fir, arborvitae, boxwood and euonymus also are likely to be harmed with drought.
About all we can do at this point is regular watering, mulch, and better plant selection going forward. Only water when the temperature is above 40 degrees and there is no snow on the ground. Midday is the best time to water. This will allow ample time for the water to soak into the soil before potentially freezing overnight. CSUE suggests we water once or twice a month this time of year. With the minimal amount of precipitation for 2018, I would definitely water twice a month.
Trees need ten gallons of water per inch of the trunk’s diameter applied slowly to give the water a chance to soak in. Water the entire dripline of the tree’s canopy using either a soaker hose or low flow sprinkler head. Remember to drain your hose and bring it indoors, otherwise it may freeze and crack.
Small shrubs need about five gallons of water a month and larger shrubs can need three times that depending on their size. Lastly, you want to have about four inches of mulch underneath your trees and shrubs. Keep the mulch away from the base of the plant by about six inches: planttalk.colostate.edu/topics/trees-shrubs-vines/1751-fall-winter-watering-drought
Let’s hope 2019 brings us more moisture. In the meantime, don’t forget to eat your black-eyed peas on New Year’s Day!
Kelley Rawlsky has an M.S. in horticulture and is the director of Bringing People and Plants Together, an organization dedicated to bringing horticulture education and therapy to the community. For more information: PeopleAndPlantsTogether @gmail.com or follow us on Facebook.