Water trees now for winter protection

Trees and shrubs are some of the most valuable parts of our yards and orchards. If you have a terrific shade tree, cherish it. Be grateful for that windbreak when snow or dust starts blowing through.

Hopefully, your fruit trees and shrubs rewarded you this summer and fall with beauty and produce.

As these faithful friends prepare for another Idaho winter, don’t forget them. One of the best things you can do right now is ensure the soil around them is moist before the ground freezes.

Going into winter with dry soil creates stressful conditions that can lead to root injury or even death.

While some areas have received rain lately, most trees still benefit from one last deep watering before the freeze.

Dry air and fluctuating temperatures are typical in Idaho winters, and roots can suffer when soil dries out.

The damage isn’t always visible right away—trees may look fine in spring but show stress later in summer through yellowing leaves, pest problems, or reduced flowering and fruiting.

To provide enough moisture, run a hose on a slow trickle and move it around the dripline of the tree.

Small trees may only need 30–40 minutes of watering; large, mature trees can take several hours. As a general guide, apply 10 gallons of water for every inch of trunk diameter. For example, a two-inch tree should receive about 20 gallons.

You may use a long screwdriver or soil probe to check moisture. If it slides easily 12 inches into the soil, moisture is good.

If it’s difficult to push in or comes out dry, more water is needed. If your soil has gravel or other obstructions, this is not a practical test.

Pay extra attention to trees near buildings, fences, or pavement where reflected heat can dry soil faster.

The low winter sun on south and west sides intensifies this effect. Windy areas also dry out more quickly, so water them more often. A layer of mulch helps conserve soil moisture and protect roots from temperature swings.

If you use a sprinkler that wets branches, water only when air temperatures are above 40°F to prevent ice buildup.

Newly planted trees are especially vulnerable to winter drought. A good rule of thumb: trees take about one year to establish for each inch of trunk diameter.

For example, a two-inch tree needs roughly two years to develop a balanced root system. Fall is a great time to plant, but make sure new trees stay in moist soil throughout winter for the best start.