Extension Educator, Horticulture
Lawn under a shade tree reminds me of a baby bird -- mostly bald and not too beautiful. A popular question at our Extension office is, "How can I get grass to grow under my trees?" That's like asking, "How can I look like the model in the magazine?" Neither have much to do with reality.
First, evaluate the amount of shade present. Does the area get any sun? Is it a dappled shade under a honey locust? Or is it the deep, dark and dry shade under a maple? Even shade-tolerant grasses need about 4 hours of sunlight. If feasible, work with a certified arborist to determine if the trees may be limbed higher or selective branches may be removed to allow more light to penetrate.
Also evaluate the soil. Is it compacted, too wet or too dry? If it is compacted, core aerification can be done now. A thin layer of compost may be added to improve the soil, but do not add more than an inch. Do not add lime unless a soil test reveals a need.
Shady lawns are best established August 15 through September 15 using seed rather than sod unless the sod was produced for shade. When seeding areas, choose a shade-tolerant grass mixture of several species and cultivars. Red fescue or other fine fescues are the primary lawn species for shade.
Among the more commonly used cultivars of fine fescues are Bridgeport, Brittany, Eco, Jamestown II, Medina, Sandpiper, Shadow II, Tiffany, Victory (all chewings fescues); Dawson, Flyer II, Seabreeze (creeping red fescues); and Nordic and Reliant (hard fescues). Perennial ryegrass and tall fescue offer intermediate shade tolerance. Perennial ryegrass cultivars for shade include Birdie II, Citation II, Manhatten II, and Palmer. Tall fescues best for shade include Falcon, Finelawn, Houndog, Jaguar, Olympic, Rebel, and Rebel II. Kentucky bluegrass generally does poorly in shade, but some of the more shade tolerant cultivars include Bensun, Bristol, Eclipse, Glade, Nugget, Touchdown, and Victa.
When seeding, be sure to get good seed to soil contact using a garden rake. Keep seed moist through frequent watering until seedlings emerge. Then water less frequently but more thoroughly.
Maintaining a quality lawn under trees requires different management strategies than lawns in full sun.
Shady lawn management includes:
Shade lawns often have problems with moss or shade-loving weeds such as ground ivy --also called creeping Charlie and a few other names I can't repeat. Despite the way it appears, the weeds or moss are not killing the grass. The weeds are taking advantage of bare soil areas because the grass is growing poorly.
If you have done everything right and the grass still won't grow in the shade, then it's time for a reality check. Many other plants such as ajuga, sweet woodruff or pachysandra grow well in shade. Add some perennials such as ferns, hostas or woodland flowers and quickly your baby bird becomes an eagle.