G6725 Grasses in Shade: Establishing and Maintaining Lawns in Low Light | University of Missouri Extension

Brad S. Fresenburg - Department of Horticulture

Trees and shade create a naturally pleasing environment in the landscape. However, it is difficult to grow grass under trees because not only the quantity but also the quality of the light changes in the shade. In full sun, light is in the "near red" range of wavelengths; in the shade it shifts to the "far red," which is less effective in photosynthesis. In addition, dense canopies, particularly those of conifers, filter out the blue component of sunlight, which is critical for plant growth. The result of these changes is a reduction in photosynthesis and its products, including carbohydrates needed for plant growth.

Leaves, leaf cuticles and stems of plants are thinner in shade. Shoot density decreases and rhizome and stolon numbers decrease. Plant tissues are succulent and there is an increase in susceptibility to environmental stresses and disease. Transpired moisture from trees and grass, and moisture from dew forming trees, take longer to dissipate, and the additional moisture may contribute to an increase in disease.

Shady conditions in combination with other plant stresses contribute to the difficulty of growing grasses under trees. For example, tree roots compete with turf for water and nutrients, and this competition can further weaken turf growing in shade. Allelopathic effects, such as the inhibitory effect of silver maple upon Kentucky bluegrass, are important among certain species of plants. Excessive organic matter from leaf litter will also inhibit grass. One or more of these factors make it particularly difficult to grow grass under sweet gum, maple and unpruned pin oak. On the other hand, grass is easier to grow under locust and poplar trees.

Select and use grasses that have improved shade tolerance (Table 1). Most of the fine fescues (hard, sheep, spreading, slender creeping and chewing's) have very good shade tolerance. Tall fescue has good shade tolerance, while Kentucky bluegrass is the least shade tolerant of the cool-season grasses. Bermudagrass, zoysiagrass and buffalograss should not be used in shady locations. In some areas where shade-tolerant grasses fail, consider shade-tolerant groundcovers or mulched beds instead of grass.

Pruning trees to improve light penetration

In Missouri, the hard, sheep, and Chewing's fescues are usually preferred over the other fine fescues when using monoculture in shady locations. Turf-type tall fescues may also provide an acceptable turf in moderate shade caused by trees.

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Another shade-tolerant grass is rough stalk bluegrass. This grass does well in cool, wet conditions found in some shady locations. It performs well in the spring and falls but will die in the summer if moisture is lacking. Rough stalk bluegrass should not be used in lawns where only one or two large trees cause thinning of turf. It is a spreading grass and may leak, causing unattractive patches in sunny areas.

Table 1

> Hard fescue

Festuca longifolia

Aurora, Biljart, Discovery, Ecostar, Osprey, Reliant, Reliant II, Scaldis, Spartan, Waldina, Spreading (strong creeping) fescue

Sheep fescue

Ovine fescue

F stucco rubra spp.

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