Winter Irrigation: When to Water Dormant Plants

By Robin Maitland · October 11, 2026

Why Dormant Plants Need Water

Roots remain alive during dormancy and continue slow metabolic processes. Without adequate soil moisture, roots desiccate and die — the plant may appear healthy above ground but fails to leaf out in spring (a common and confusing failure).

When to Water

Water when all of these conditions are met: air temperature above 40°F, no snow cover, and soil is dry to 3 inches deep. In most climates, this means watering once or twice a month from November through February.

How Much to Apply

Apply slowly and deeply. For trees: 10 gallons per inch of trunk diameter, delivered over 30+ minutes using a slow-drip soaker hose. For shrubs: 5 gallons per plant. For perennial beds: enough to moisten the top 6 inches.

Priorities

Evergreens: Highest priority — they transpire all winter
Plants installed this year: Root systems are not yet deep enough to find moisture
Sandy soil sites: Drain fast, need more frequent winter watering
South-facing slopes: Warm faster, soil dries sooner

What to Avoid

Do not water when temperatures are below freezing — water will ice on the surface. Do not overwater — saturated soil in cold conditions promotes root rot. Check soil moisture before every application.