Growing Turfgrass in the Shade

Shade-tolerant grasses let your lawn get lush amid big trees

Lisa Klein: Ask a Master Gardener

Saturday, June 27, 2015

Q: Is it possible to have a lush lawn while still enjoying my large shade trees? Carrie, Tulsa

A: Growing grass in shaded areas is a common problem for homeowners. All turfgrass requires photosynthesis to produce energy for growth. Anything less than four hours of sunlight per day is really not sufficient for the photosynthetic process to do what it needs to do.

Fortunately there are grasses that are more shade tolerant. Use these shade-tolerant varieties along with some modifications in turf care management to have the lawn you desire.

The first thing you should consider is increasing the amount of sunlight by raising the tree canopy and thinning out limbs and branches. Depending upon the size and age of your trees, this may not be cost effective. Obviously if the area you are struggling with receives shade from a house or building, removal is usually not an option.

When choosing seed, you will want to look for a high-quality blend of seeds. The most shade-tolerant grasses grown in our area are tall fescue and Kentucky bluegrass. The next most tolerant is zoysia grass, which will tolerate light shade (needs at least four hours of sun). St. Augustine also will tolerate light shade but, due to cold intolerance, will only grow in extreme southern parts of the state.

If you are starting from scratch, mid-September to mid-October is the best time for seeding or sodding cool-season grasses. This planting window allows enough time to develop a mature root system before the heat of the following summer. Depending upon sunlight, watering practices and general wear and tear, yearly reseeding of fescue and Kentucky bluegrass may be needed.

Cool-season grasses have certain mowing requirements. It’s important not to overcut your grass. Increase the mowing height to 3 inches and mow the shady areas only when it’s necessary. Grasses with taller blades are better able to use the available sunlight to make energy and survive shade.

Fertilization and watering needs of cool-season lawns are also different than those of your sunnier areas. Fertilization decisions should always be based on a soil test, but in general shade turfgrass needs half the amount of nitrogen as full-sun turf. Try not to water too heavily or too often, which can significantly increase to chances of disease.

If it’s practical, limit excess foot traffic and pet exposure, especially when trying to establish your turfgrass. In fall, keep leaves off newly seeded lawns; leaves block out the much-needed sunlight.

For more complete information on shade turf management and suggested varieties for Oklahoma, there is an excellent fact sheet available,  HLA-6608, “Managing Turfgrass in the Shade in Oklahoma, from the Master Gardener web site, tulsamastergardeners.org.  

Garden tips

Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk, and remove the least desirable trunk as soon as it is noticed.

Most varieties of mums are more productive if “pinched back” now. Either pinch off with fingers or cut to remove an inch or so of limb tips above a leaf. This results in the growth of new limbs and a fuller plant. Do not pinch after mid-July or it will interfere with fall blooming.

Watch for tiny, sap-sucking insects called aphids on roses, perennial flowers, shrubs and vegetables (especially tomatoes). They produce a sticky substance called honeydew. Many can be dislodged with a hard spray from your garden hose. Two applications of insecticidal soap or horticultural oil will usually greatly reduce any aphid damage to your plants.

Crape myrtles are one of the few shrubs that should be planted in the middle of summer. Growth of new roots of these plants occurs best with summer soil temperatures.