When planting new trees, shrubs and other ornamentals, establishing new roots is the key to successful and healthy plants, says a gardening specialist in Penn State's College of Agricultural Sciences.
"If you just take a plant out of its container, dig a hole and cover the root ball, that's almost guaranteed to slow or limit root growth," says Robert Nuss, professor of ornamental horticulture. "The most important element in gardening is helping plants establish new roots into the soil."
Nuss suggests that gardeners follow these tips:
- Remove plastic containers, plastic twine or plastic burlap. "Plastic will not break down in the soil and allow roots to grow," Nuss says. "Some people recommend making vertical cuts in plastic, but I believe plastic always should be removed."
If left tied around the trunk of the plant, the plastic twine often used to secure the burlap wrap on the root mass will cut into the bark and girdle the stem as the plant grows, Nuss says. "If you can't tell if it's plastic, remember that plastic melts and organic material burns when held to a flame," he explains.
- Remedy girdling roots. Nuss says many container-grown plants can be seriously restricted when roots grow in a circular pattern in the bottom or along the sides of the container. Usually, the root mass looks enveloped by a "basket" of roots. "You can disrupt the girdling pattern by cutting four to six vertical slices on the sides of the mass after removing it from the container and an 'X' across the bottom of the roots," Nuss explains. "The cuts will encourage outward growth into the soil."
- "Butterfly" the root mass. Nuss defines butterflying a root mass on container-grown plants as slicing through the center of the bottom of the mass. "Then you spread or flatten the root mass," Nuss says. "Butterflying disrupts the root pattern and also allows for shallow planting, which is an advantage in heavy or slow-draining soils." He warns against disturbing the root ball on plants that are growing in soil at the nursery and are subsequently dug out.
- Water, water everywhere. "Most gardeners will water faithfully for the first day and for a few weeks after that," Nuss says. "However, root systems will grow well only if the soil is uniformly moist all summer."
The soil surrounding the planting hole often is drier than the fill used to surround the root ball. "You need to pay attention to soil moisture in the entire area to prevent the fill from drying out," Nuss says.
Nuss also recommends laying mulch over the fill soil and mulching several feet past the diameter of the planting hole to keep the proper levels of moisture around the root zone of newly planted trees and shrubs. Keep all mulch several inches away from the trunk or stem of all plants.
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