How to Grow Grass in a Shaded, Mossy Yard

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Achieving a great, grassy lawn isn't always as easy as it seems. Different types of grass require different amount of sunlight and soil pH, making it a challenge for homeowners with mossy lawns to find a single, consistent grass seed that suits all areas around their home. One of the biggest obstacles to success is lack of daylight, and in those locations, usually with no effort, moss takes over.

"Moss grows where it is generally dark and wet. So, usually it's an area that's heavily shaded," shares Craig Elworthy, founder of Lawnbright. Sometimes the moss is dense and fills in nicely. Other times, it's easily torn by foot traffic, lacking the root system to make it durable. He makes several recommendations to help homeowners (like me!) who want to grow grass in place of moss patches, but struggle:

Look Up

"First, many grasses do better with more direct sunlight," shares Elworthy. "Look at the sunlight in that area and consider trimming branches." Hire an arborist who can help perform a tree health assessment. They can check for dead branches or make recommendations to open up trees in your yard to let in more hours of sunlight. And, you never know, they might find a diseased tree that's at risk of falling and recommend that it be cut down.

If you're stuck with a shady spot, be sure to choose a shade-tolerant grass seed. Many can tolerate moderate shade, just remember that they may require reseeding year-to-year for thick coverage.

Related: Winter is the Best Time For a Tree Evaluation—Assess For Damage and Disease Today

Test for Acidic Conditions

Moss tends to thrive in acidic soil, while most grasses prefer a slightly alkaline pH. Test the soil pH using a soil testing kit. If you have acidic conditions, consider adding lime to raise the pH to a level more suitable for grass. Lime can be sprinkled across the moss to help slowly eliminate the acid soil and promote a healthy lawn during future growing seasons. (Sprinkle it before or during a rainstorm for best effect!)

Additionally, compacted soil can make matters worse. You can incorporate organic matter such as compost or well-rotted manure into the soil to improve its fertility and structure. This can provide essential nutrients for the grass seeds to grow.

Check Irrigation and Improve Drainage

"Areas that don't receive as much sunlight need less irrigation, so you may find that you can cut back irrigating certain areas around your home," shares Elworthy. Excessive moisture isn't necessary for most grasses.

Poor drainage can accelerate moss growth. Is your problem area simply a low-lying area? Do you have a downspout diverting rainwater from your roof into your yard? "You usually want to look at adding soil and leveling the area," he adds. Moist soils often have drainage issues, so if you want your grass seed mix to take hold, it's best if you fix the grading of the yard.

Prep Properly

Prepping the lawn for new grass seed is important. Excessive moss growth can potentially smother grass seed if it grows thickly enough over the seeded area. Thick moss can prevent grass seeds from reaching the soil, inhibit their germination, and compete with them for nutrients and moisture. As such, it's not a terrible idea to take all moss out before sprouting grass seedlings.

"For moss removal, use a moss killer, such as an iron-based weed killer," recommends Elworthy. Iron-based weed killers are generally considered safer for grass compared to traditional herbicides containing chemicals like glyphosate. Once the moss is gone, you can remove dead material and spread your new grass seed.

Choose the Right Seed

Select a grass type that is suitable for the growing conditions in your area and that can tolerate shade if the area where you want to grow grass over moss receives limited sunlight. Don't forget to factor in whether you're using warm-season grass or cool-season grass. Late spring is a great time to lay seeds and promote healthy grass growth.