Written by Master Gardener Joyce Hylton and edited by Extension Agent Kirsten Conrad
As we go into the colder temperatures of the year, a very important concern continues to be soil moisture content. Our recent rains notwithstanding, this area has received very little rain in the last 6 months. This fall, all of our plants are a bit ‘thirsty’ as they enter their dormant season.
Young or newly planted trees that have not spread their feeder roots into the surrounding soils will require more attention and regular irrigation because of limited abilities in obtaining water in their growing environment. All newly planted trees should have 1 inches of water per week- even in the winter- for two years.
This is also especially true of conifer trees and evergreens that have needles that are subject to winter burn. Winter burn occurs when evergreen trees can’t get enough water from the soil to offset the drying effects of wind and extreme cold.
The key to survival is giving trees adequate moisture before winter freezes the world around them. Once the ground is frozen, watering is not possible. Up to 3 inches of mulch can be applied around the planting zone that will protect roots from freeze/thaw cycle and prevent water loss.
The following is excerpted from Winterize Your Trees by Lindsey Purcell, a Purdue University publication.
Watering. Whenever rainfall is insufficient for extended periods, supplemental water is needed, especially on newly planted and less-established trees. Follow the “5 + 5 rule,” which says to provide 5 gallons of water plus another 5 gallons for every diameter-inch of tree trunk. This should provide plenty of water to help a tree during times of inadequate rainfall. For mature and well-established trees, 1 inch of supplemental water applied to the root zone every week should keep soil moisture adequate. Continue to water through the fall until the ground is frozen, so that trees have ample moisture to survive the winter months and are ready for spring growth. If limited rain or snowfall in winter indicates drought, it may be necessary to water in the winter. The best time for winter watering is a warm day, when the temperature is above 40 degrees. Refer to Drought? Don’t forget the Trees! (FNR-483-W) for more information on watering trees.