Kim Snowdon
Colorado Master Gardener

“Autumn, the year’s last, loveliest smile.” — William Cullen Bryant

Autumn in Colorado has been especially beautiful this year, showcasing leaves ablaze with color. But it’s also been very dry. So winter watering is critical in this region’s arid, high-desert climate.

Trees, shrubs, lawns and perennials should be watered one or two times per month during prolonged dry spells between October and March. December, January and February are typically dry, windy months in the Pikes Peak region, and evaporative water loss can desiccate plants. The damage might not be noticeable until spring.

Water early in the day when air and soil temperatures are above 40 degrees with no snow cover to allow moisture to soak in before temperatures drop in the evening.

TREES

Established large trees have a root spread equal to or greater than the height of the tree. Focus watering within the drip line (the edge of the canopy where rain drips down) from the edge of the canopy to halfway to the trunk and 2-3 times this distance out from the canopy.

It’s even more important to water newly planted trees. Trees with a smaller diameter trunk will establish more quickly. For example, in ideal climate and soil conditions, a one-inch diameter tree will take one year to establish and a two-inch diameter tree will take two years to establish.

Tree types that are especially sensitive to dry winters are birches, maples, lindens, dogwoods, willows and mountain ashes. Evergreen species are also vulnerable because they don’t lose their foliage.

Water several locations around the tree to ensure good distribution, about 10 gallons of water per inch of trunk diameter (measure 6 inches above the ground). Use a hose-end sprinkler, soaker hose or deep root watering fork.

SHRUBS

Give five gallons of water twice a month to newly planted shrubs. Large established shrubs benefit from approximately 18 gallons of water once a month. Water within the shrub drip line and at the base of the shrub.

LAWN

Deep, infrequent watering that soaks to a depth of 3-5 inches once or twice a month is better than more frequent shallow watering. Areas that receive more sunshine or are exposed to wind or on a slope will need more water than areas that are shady. Make sure water isn’t running off the surface. Avoid watering on windy days.

PERENNIALS

Water requirements may vary. Bare root plants take longer to become established than container plants and may need more water. Fall plantings may take longer to establish than spring planted, but cooler temperatures in autumn lessen the stress on new plantings. Those planted in more exposed sunny or windy positions will require more water.

Applying mulch, especially around the perennials, will help moderate soil temperatures and protect delicate roots from potential soil heaving.

Caring for your trees, shrubs, lawn, and perennials during the dry winter months will go far to ensure they thrive next year.

Submit gardening questions via ask.extension.org and they will be routed to El Paso County Master Gardeners, or call 719-520-7684. The in-person help desk is closed for the season. Questions submitted via Ask Extension will be answered remotely and phone messages will be returned biweekly.