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Advice on planting container-grown trees and shrubs
“The best time to plant a tree was 20 years ago. The next best time is now.”
— Chinese proverb
Unlike the hard-wearing daylily that can be uprooted time and again, woody plants should grace the garden space we give them for decades. Their planting should be approached thoughtfully and methodically.
At planting, a container-grown tree or shrub has less than 20 percent of the absorbing roots as the same size plant established in the garden. The gardener’s goal at planting is to promote rapid root growth and reduce the water stress imposed by a limited root system. Soils in Maine are often compacted or poorly drained, conditions that give woody plant roots a hard time. Compaction of the soil prevents adequate aeration of the root zone, while too much water drowns roots. Neither of these conditions are remedied by planting in a hole barely larger than the root ball.
Roots of plants placed in small holes soon reach the compacted native soil and, unable to penetrate it, begin to circle in the hole, much like the circling that occurs when roots meet the impenetrable sides of a pot. Circling roots can become girdling roots, cutting off water flow to the plant like a crimp in a garden hose.
Small planting holes surrounded by compacted soil may also drain slowly after a hard rain. Roots die in the waterlogged soil.