Colorado’s dry winters can leave trees short of moisture, especially when snowfall is light and warm, windy weather dries the soil. Deciduous trees are dormant, but their roots can still take up water when the soil is unfrozen. Evergreens also lose moisture through their needles during winter; if the ground is frozen, their roots cannot replace it quickly, which can contribute to winter desiccation.

Winter watering helps when the soil is dry. It is not needed on a fixed schedule, and too much water can harm roots.

When to water

Check soil moisture during extended dry periods, particularly for newly planted trees and trees growing in exposed locations. Water on a mild day when the soil is not frozen and temperatures are expected to stay above freezing long enough for the water to soak in. Avoid watering frozen ground, creating icy walkways, or leaving hoses connected where they may freeze.

Snow contributes moisture as it melts, but a light snowfall may not wet the root zone. Check the soil rather than relying on the appearance of snow cover. If the soil is still moist several inches below the surface, wait and check again later.

How to water

  • Apply water slowly over the root area beneath the canopy and beyond it where practical, rather than pouring it against the trunk.
  • Water deeply enough to moisten the soil without leaving standing water or saturating it.
  • Adjust the amount and frequency for the tree’s age, soil drainage, recent precipitation, and local conditions.
  • Check the soil again before watering. If it is frozen or already moist, wait.

There is no single number of minutes or one watering interval that works for every tree and soil. A soaker hose or slow trickle can help apply water gradually, but monitor the area to make sure water is soaking in rather than running off.

Protect roots and reduce winter stress

Maintain a 2–4 inch layer of organic mulch over the root area where practical, keeping mulch several inches away from the trunk. Mulch moderates soil temperature and helps retain moisture; piling it against the trunk can cause problems.

Evergreens in exposed sites may benefit from a temporary wind screen, but wrapping the entire tree tightly can trap moisture and damage branches. Ask an arborist about the right approach for the species and location.

If you notice damage

Brown needles or foliage can result from winter drying, but may also have other causes. Wait until spring growth makes the extent clearer, and ask an arborist to assess severe or widespread damage. Avoid pruning healthy branches or increasing watering without checking soil moisture first.

The goal is to keep roots from drying out—not to keep the soil wet all winter. When in doubt, check the soil and follow local Colorado State University Extension guidance for your tree and site.