Fall and Winter Watering Desk: how many gallons your trees need
Leaves drop, but roots keep working until the ground freezes, and evergreens keep losing water all winter through their needles. Most people stop watering in October. Give a tree 10 gallons for every inch of trunk diameter, measured 6 in above the ground, once or twice a month during a dry spell. Water only when the air and soil are above 40 F and the ground is bare, and water at midday so it soaks in before a cold night. Enter your trunk sizes to get gallons, hose time, and how many years the tree stays a watering job. Your list saves on your device. No account needed.
Free fall and winter watering calculator. Enter a trunk diameter and get gallons per watering at 10 gallons per inch, hose time, and how many years the tree stays a watering job. Plus the rules: air and soil above 40 F, no snow cover, water at midday, soak 12 inches deep. Sourced from university extension.
The three rules
- Water only when air and soil temperatures are above 40 F, with no snow cover (Colorado State).
- Water at midday so the water has time to soak in before it freezes overnight (Colorado State).
- Soak slowly to about 12 in deep. With a deep root needle, stay above 8 in (Colorado State).
How much water, by plant
| Plant | Amount | How often |
|---|---|---|
| Tree | 10 gallons for each inch of trunk diameter. A 2 in tree gets 20 gallons. | One or two times a month in a dry spell with no snow cover |
| New shrub, planted this year | 5 gallons | Twice a month, October through March |
| Established shrub under 3 ft | 5 gallons | Once a month, October through March |
| Established shrub over 6 ft | 18 gallons | Once a month, October through March |
Measure the trunk diameter with a ruler 6 in above the ground (Colorado State).
Worked examples
| Trunk size | Water per watering | Years until established |
|---|---|---|
| 1 in trunk | 10 gallons | 1 year to establish |
| 2 in trunk | 20 gallons | About 2 years |
| 4 in trunk | 40 gallons | About 4 years |
| 10 in trunk | 100 gallons | About 10 years |
Trees generally take one year to establish for each inch of trunk diameter (Colorado State). A 2 in caliper tree needs at least two years.
Why winter watering matters
Newly planted trees are the most likely to be hurt by winter drought (Colorado State). Evergreens lose moisture through their needles all winter, and once the ground freezes the roots cannot replace it, so they go into winter short of water and the needles turn brown (Iowa State). Iowa State adds that properly watered young trees are less likely to show tip dieback and sunscald. Keep watering until the ground freezes, then start again in spring when it thaws (Iowa State).
Guides
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Sources
- Colorado State University Extension, Fall and Winter Watering of Plants and Trees (7.211)
- Iowa State University Extension, Fall Care of Newly Planted Trees
- Iowa State University Extension, Caring for Newly Planted Trees through Winter
- Iowa State University Extension, Protecting Trees and Shrubs in Winter
- University of Minnesota Extension, Protecting trees and shrubs in winter
- Minnesota DNR, Caring for trees
- UF/IFAS Gardening Solutions, Planting and Establishing Trees