Published on Wednesday, 30 November -0001 00:00
We love our trees and we love to have a lush green lawn, but the two are not always compatible. No grass will grow for long in the dense shade that results from trees, but with proper care, you can grow an acceptable lawn in partial shade. Lawns in shade areas are typically thin, weak and generally do not have the ability to tolerate or recover from stress as compared to lawns growing in full sun.
In spite of what we often hear, leaves and needles from trees do not cause the soil to become acidic; it is the lack of light, not soil acidity that causes thin lawns in the shade. To grow a presentable turf, the area must receive about 50 percent sunlight. This can be filtered through trees or it could mean several hours of full sun followed by diffuse light the remainder of the day. Try to increase light by pruning out branches from the trees. Sometimes just removing the lower branches will help.
The next step to growing good grass in shady areas is to make sure you choose shade-tolerant turf grasses. The most shade-tolerant types are fine-leaved fescues, such as creeping red fescue and chewings fescue. These fescues should be mixed with Kentucky bluegrass varieties such as Glade, Nugget, Touchdown, or Sydsport, which have some degree of shade tolerance, at the rate of two parts fescue to one part bluegrass.
Although we are tempted to add fertilizer to make the grass grow faster, the opposite should be true in shady areas. Grass grows more slowly in shade and slower growing grasses cannot make use of as much fertilizer. Furthermore, fine fescues, even when growing in good sunlight, need only half the fertilizer needed by Kentucky bluegrass. Fertilize three times a year (around Memorial Day, Labor Day and later October), at half the normal rate.
Fine fescues are more drought-tolerant than bluegrass, which allows them to compete well with the demand for water by the trees. When watering shade lawns, water less often and water deeply. For good turf, shaded areas need a good soaking about once a week during hot periods and a soaking once every 10 to 14 days as the weather cools in late August and September.
Since the main limiting factor for good growth is lack of light, shady lawn grasses need more leaf surface for photosynthesis. Therefore, keep the grass a bit longer; usually a little above three inches, but cut the grass before it reaches 4 1/2 inches high. Because fine fescues are a bit thin and wispy, they tend to lie down in front of the mower making it necessary to keep your lawn mower blades sharp.
Because shady lawns are easily smothered by heavy leaf fall, prompt leaf removal is important in the fall. Fine fescues are rather shallow-rooted and can be torn out by hard raking. Gently remove the leaves several times in autumn and again in early spring to allow as much light as possible to reach the grass.
De-thatching shady lawns is usually not necessary because the types of grasses that grow in shade seldom create a thick thatch layer. Core-aeration may be useful each fall if your soil is heavy and compacted. Moss growing in the shady lawn indicates that the soil may need aeration.
No matter how well you care for it, shaded grass will probably thin over the years. The best time to overseed is between Aug. 15 and Sept. 15. Although you can overseed in the spring before the trees leaf out, weed competition may be more of a problem at that time.
If, after several years of effort, grass still doesn't grow well enough in the shady area, you may have to choose an alternative. There are some shade tolerant ground covers that work well and, if all else fails, you can use a decorative mulch under the trees.