We’re not just throwing shade – that grass looks pretty dismal under the trees. The trees, shrubs and surrounding buildings create an overcast area in the lawn that moves with the sun, and it’s just not enough light for a healthy lawn. And there’s no better place on a hot summer day than cool grass in the shade.
“Too much shade can be problematic and lead to deterioration of turf quality and tolerance,” says Jacob Taylor, a master’s student from Hampton who is involved in a Clemson University study on shade and iron fertilization of specific grasses. “We’re looking at what can be done to combat shade stress and retain acceptable turf quality.”
Some lawn grass varieties can get by with fewer hours of direct sunlight, but can you expect to fill in the bare areas enough to matter? “It depends on how much shade is present in the lawn,” says Peter Landschoot, Professor of Turfgrass Science at Penn State College of Agricultural Sciences. “If you have four to five hours of direct sunlight per day, you should be able to grow a decent lawn, provided you have good drainage and shade-tolerant grasses in your lawn. If you only have a couple of hours (or less) of light per day, your lawn will probably be thin and struggle, no matter what type of grasses you have and despite a well-planned management program.”
Before you rush to reseed, understand your lawn’s short-term and long-term needs when it comes to sunlight.
Assess Your Shadiness
The first step is to get to know your lawn and its sunning schedule. All types of turf grasses need a certain amount of light, irrigation, and nutrients, but growing grass in the shade requires a few adjustments. Shade from trees, shrubs, buildings, and even lawn ornaments can prevent light and water from reaching the grass.
- Find your compass. What direction does your lawn face? Does it have eastern or western exposure? That will help you learn how much sun is available. A shady area’s microclimate could vary from a nearby area that is flooded with sunlight.
- Study the soil. If you haven’t had a soil test done in the last few years, get one. Once you have the results, you can prepare the soil as recommended before seeding, and give any future grasses a head start.
- Picture the result. The sun’s rays are stronger at noon, and sunny or dappled areas can change as the day goes on. Grab your camera and choose a spot that faces the shady areas in the lawn. Schedule the pictures for the morning, noon, mid-afternoon, and early evening, so you can determine how many hours of full sun or partial sun a particular spot gets.
- Pull the invaders. Ground-covering weeds such as English ivy can take over shady spots and make it harder for grass to survive. Get rid of those pesky space-hoggers before seeding.
- Weather or not. It’s not just the shade that affects the health of lawns. Extreme changes in temperature, lack of air or wind, humidity, and an increased carbon monoxide level can also have a bearing on whether the grasses thrive or merely survive.
What’s Your Climate?
- Zone out. Look up your area on the USDA’s Plant Hardiness Zones and Koppen Climate Classification maps. Knowing your zone will help you choose the right grass variety or combination of varieties.
- Know whether cool-season or warm-season grasses thrive in your area. Cool-season grasses grow best in early spring and fall temperatures between 65 and 80 degrees Fahrenheit. Warm-season grasses do well in areas with summer temperatures of 75 to 90 degrees.
- Ask for help from local experts. Contact your local extension service or talk to turfgrass experts about the best types of shade tolerant grass for your area, and about the best fertilizing schedules.
- Copy the look. Do you like the texture or look of a grass or low-growing plant in a shady park or public lawn? Ask the groundskeeper about their lawn care schedule, and what grasses or plants are being used.
No Exact Meaning for ‘Partial Sun,’ ‘Shade Tolerant’
Shade can have an effect on the overall health of grass plants, including weaker root systems, more susceptibility to disease or insect damage, and reduced vigor and growth. But if you buy a plant or seed bag labeled “partial sun” or “shade tolerant,” it’s no guarantee. Those are relative terms. They mean only that the seller is asserting that this product does relatively better than a full-sun variety.
- Pick a grass that can take it. “I don’t know of any regulations governing the word “shade tolerant” on grass seed labels,” says Landschoot. “However, all seed labels must disclose the contents of the container (% seed [by weight] of each grass species and cultivar, and % germination). “Typically, shade tolerant seed mixtures in the northern U.S. have one or more of the fine fescues (creeping red fescue, Chewings fescue, and/or hard fescue) as the predominant component. A good quality turf-type tall fescue could also serve as a shade-tolerant species, but this type of grass is less tolerant of shaded conditions than the fine fescues.”
- Catch the right amount of rays. If a grass seed label says the seeds require full sun or partial shade, what does it really mean? “’Full sun’ usually means no shade whatsoever. Partial shade can mean just about anything depending on who you talk to,” explains Landschoot. “For me, it usually denotes a dappled effect, where the turf gets some sun (at least 4-5 hours of light throughout the day), and some shade as the day progresses.”
|Grass Varieties' Tolerance for Shade|
|Tolerance||Cool-season grass varieties||Warm-season grass varieties|
|Source: James Beard, "Turfgrass, Science and Culture." This is a general guideline; many grass varieties have been developed with different shade tolerances.|
Steps You Can Take to Grow Grass in Shade
Grass can become stressed in low-light conditions. Give it a boost by doing a few things:
- Turn on the light: Trim the canopy. Look at the tree canopy that is shading the area. Are the branches crowded together, preventing sunlight from seeping through? Are there dead branches that can be removed? On tall, mature trees, how many more hours of daylight could you claim beneath if you trimmed of all the lowest branches? Contact an arborist for the best way to safely prune or cut back branches.
- Look beneath. Trees have complex root systems that can cover several times more than the canopy size. About half of the tree roots stay in the upper layer of soil, so they are strong competitors for water and nutrients.
- Wetland check. Shade can cause moisture to remain in the soil and allow fungus or moss to grow. Level out any of those areas to balance irrigation or drainage. Water deep and infrequently, and apply fungicides if necessary.
- Leaf away. Remove fallen leaves and other debris as quickly as possible, to allow grass to receive as much light and air as possible.
- Pay dirt. If you haven’t done a soil test and prepared ahead of time, test and treat your soil now. Soil amendments such as lime can help balance pH and feed the grasses. “Thicken the turf as much as you can (apply fertilizer, apply seed of a shade-tolerant grass species, etc.) in the spring before the tree leaves expand and block the sunlight,” suggests Landschoot.
- Overseed it. Seed in mid-spring and in the early fall for cool-season grasses, or in early summer for warm-season turf. Water well after seeding.
- Raise the bar. Mowing higher gives the weak blades a chance to process the sun they receive. Raise the mower blade a 1/2 inch to a full inch higher than other parts of the yard, and a minimum of 3 inches.
- Let it rest. Try to keep foot traffic to a minimum, so grass can recover and grow.
When the Grass Isn’t Greener
If the grass just isn’t showing signs of recovery or repair, you might want to consider other methods:
- Apply mulch. If you have heavy shade, don’t even try to grow grass,” says Landschoot. “Grow ground cover plants or just mulch the area.” Don’t pile mulch up against the tree’s trunk, but extend the mulch out to the canopy line of the tree.
- Cover it. Opt for shade tolerant ground cover. Stay away from invasive plants and incorporate pollinator-loving plants that spread. Ground covers are great for sloped areas or spots with poor drainage.
- Don’t try to change what nature gave you. Wild plants adapt to the condition, creating relationships and networks with other plants and animals. A combination of grasses and spreading plants could offer a lush green landscape with fewer cuttings. Blend this mixture into the larger expanse of lawn that receives more sun to give it a more uniform look, and you’ll be blade in the shade.