Gardens, lawns and trees still require water, maintenance in mid-winter
Despite the cold, dormant appearance of lawns, trees and perennial beds this time of year, experts are reminding homeowners the dead of winter can be one of the most stressful seasons for their outdoor plants, especially in the Cowboy State’s dry and windy climate.
From persistent winds and low humidity to temperature swings and limited snow cover, winter conditions can quietly take a toll below the soil’s surface.
According to horticulture experts from Kansas State University (KSU), the Cheyenne Botanic Gardens and Plant Select, strategic winter maintenance – especially supplemental watering – can make a big difference between healthy spring growth and long-term plant damage.
Winter stress
This winter, large swaths of the West have experienced unprecedented mild temperatures and low moisture.
However, even when winter brings occasional snowfall, KSU Horticulture Expert Cynthia Domenghini notes it often isn’t enough to replenish soil reserves, as light, infrequent snow typically provides only a fraction of an inch of usable moisture, most of which is lost to evaporation.
Therefore, she says winter watering is critical, although it is often overlooked.
“Yards may need another shot of moisture, even after recent rain or snow to alleviate stress in lawns and gardens,” she states in a Jan. 13 KSU Extension News Service article.
In a separate article, Dr. Tyler Mason, a horticulturist at the Cheyenne Botanic Garden, notes Wyoming’s fierce winter sun and strong winds compound the problem, drying out soil and foliage while roots remain unable to access frozen moisture.
Experts at Plant Select, a nonprofit offering plants designed to thrive in the High Plains and Intermountain West, further mention extended periods of dry conditions can damage root systems, weaken plants and delay or prevent spring emergence entirely. In trees, the effects may not appear immediately and can take years to fully manifest.
Supplemental watering
When it comes to supplemental winter watering, Domenghini emphasizes quality over frequency.
“A good, deep watering with moisture reaching at least one foot down into the soil is much better than several light sprinklings that just wet the top portions of the soil,” she says. “A deep watering will ensure the majority of roots have access to water.”
To test soil moisture, Domenghini recommends pushing a metal rod or wooden dowel into the ground. Dry soil will resist penetration, while moist soil will allow the tool to slide in more easily. The depth reached gives a good indication of how far moisture has penetrated.
Experts at Plant Select and the Cheyenne Botanic Garden note the timing of supplemental winter watering is key.
“Water once or twice a month during extended dry periods with no snow cover,” Plant Select suggests. “Water on days above 40 degrees Fahrenheit, ideally when there is no snow cover and the ground isn’t frozen, and water mid-day so it has time to soak into the ground.”
Plant Select experts also point out not all plants require winter water, but some are more sensitive to cold, dry conditions than others.
Evergreens and conifers, for example, do not go fully dormant and continue to lose moisture through their needles.
Newly-planted trees and shrubs – sometimes even those planted within the past two to three years – also have limited root systems and are more sensitive to drought.
Other plants benefiting from winter watering include fall-planted or over-seeded lawns, perennials planted in the fall, shrubs planted within the past year, plants located in windy areas or south- and west-facing exposures and plants near buildings or fences that reflect heat.
On the other hand, established xeric plants do not require winter watering since they are adapted to long periods without moisture and typically tolerate dry winters without lasting damage.
Additionally, the experts explain different plants require different approaches to supplemental winter watering.
For newly-planted trees, Domenghini recommends drilling a small hole near the bottom of a five-gallon bucket and letting water slowly drip out near the base of the tree.
“Refill the bucket until you apply 10 gallons. Slow-release bags with micropores can be purchased as an alternative to using a bucket. Larger trees planted two to three years prior may require more water,” she says.
Domenghini also says larger trees may benefit from a soaker hose placed in a circle halfway between the trunk and the dripline – the outer edge of the branches. Smaller trees may require several loops of hose to adequately water the root zone.
For newly-established foundation plantings or garden beds, hooking both ends of a soaker hose to a Y-adapter helps equalize pressure and encourages uniform watering. Fall-seeded lawns should be watered with overhead sprinklers, aiming to reach at least six inches deep.
As a general winter guideline, Cheyenne Botanic Gardens recommends applying about 10 gallons of water per inch of trunk diameter for trees during extended dry periods.
Protecting perennials
Experts across the board note – although critical – supplemental watering is only one piece of winter garden maintenance.
“Selecting zone-hardy plants is the most important step in helping perennials overwinter,” Mason writes. “Be sure to look on the back of plant tags at a nursery or garden center for Zone Four hardiness or lower.”
He continues, “Zone Five plants can sometimes be marginal in Cheyenne’s climate due to strong winds and low levels of precipitation. Warm sunny days and cold clear nights wreak havoc on a plant’s ability to moderate internal temperatures. Therefore, regulating temperature changes with insulation is essential.”
Mulching is one way to insulate plants and plays an important role in moderating soil temperature and conserving moisture.
Experts recommend a two- to three-inch layer of mulch placed several feet around trees and shrubs to help protect roots. However, they emphasize mulch should be kept several inches away from the trunk of trees to prevent rodent damage.
Vegetable gardens also benefit from mulch, as it can improve soil fertility and increase yields the following growing season.
Preventing sunscald
According to Mason, sunscald is another common issue for Wyoming growers to be aware of this winter, particularly when it comes to young trees with thin or dark bark.
“Sunscald injury comes in the form of discolored bark, sunken areas and bark splitting, which leaves dead tissue inside the affected area,” he explains. “This wound creates stress for the tree or can lead to insect and disease infestations.”
Mason further notes sunscald injury generally occurs on the south side of a tree’s trunk during extreme day and nighttime temperature swings.
“The sun heats the south side of the trunk, encouraging cells to expand, while the north side of the trunk stays cool,” he explains. “When the sun sets, the bark on the south side suddenly contracts leading to bark splitting. Splitting of bark can be exacerbated by dry soils, so be sure to water trees if you go many weeks without moisture or snow cover.”
Mason says tree wrap provides an effective and inexpensive solution to the problem, as wrapping the trunk and lower limbs reflects sunlight and moderates temperature fluctuations.
He recommends applying wraps in the fall once nighttime temperatures dip below freezing and then removing them in the spring after the last frost.
Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to roundup@wylr.net.
