Irrigation critical for newly planted trees and shrubs

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

After a fairly cool start to our spring, it looks like we will jump right into summer with temperatures forecast in the 80s and even 90s in the next week. With such warm temperatures this early in the season, it is essential to keep newly planted trees and shrubs watered to insure survival and rapid establishment. New trees, whether container-grown or balled-in-burlap, need time for their roots to grow into surrounding soil in order to survive the transpiration water loss associated with afternoon temperatures in the 80s and 90s. When planting trees in the spring, remember to give them a good watering immediately after planting and then once a week for the first two months. For the rest of the summer, watering once every two weeks should be adequate unless we get into an especially hot and dry spell.

MSU campus arborist Paul Swartz is an advocate of using irrigation devices such as GatorBags to water newly planted trees. The bags are designed to trickle out 20 gallons of water over six to eight hours; this improves the efficiency of water use by reducing surface run-off and allowing the water to soak deeper into the soil, promoting greater rooting. “This year we’re having a major planting effort on campus and we’re using about 1,200 Gator Bags” Swartz notes. “They give us flexibility because we can zip two or three together for larger trees.” MSU Landscape Services crews fill the bags once a week during the establishment year.

Mulching is another key to improving survival and early growth on newly planted trees and shrubs. As we’ve noted before, mulching provides multiple benefits for plants; conserving soil moisture by reducing surface evaporation and reducing weeds are highest on the list. Our research on mulch at the MSU Horticulture Teaching and Research Center suggests that almost all organic mulches (wood chips, ground or shredded bark) can fulfill these functions. To paraphrase the old Nike ads, our motto is, “Mulch: Just Do It!”

GatorBags around trees on MSU's campus.

Dr. Cregg's work is funded in part by MSU's AgBioResearch.

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