How To Treat Perennial Ryegrass Bald Spots In Your Lawn

Perennial ryegrass is a cool-season grass variety that's ubiquitous on lawns throughout cool, mild regions, such as the Pacific Northwest. If you happen to own a lawn with perennial ryegrass, you've probably noticed the turf's annoying tendency to grow in clumps and not recover its bare spots naturally. This happens for two reasons. For one, perennial ryegrass does not tolerate heat and drought well, so hot, dry summer conditions may kill off patches of the turf instead of simply making them dormant — those are likely the bare spots you're seeing. 

And the reason the turf doesn't spread back over the bare spots is because — well — perennial ryegrass just doesn't spread quickly enough. It doesn't have rhizomes that can help it grow sideways aggressively the way Kentucky bluegrass does. Instead, perennial ryegrass has a bunchgrass growth habit, which causes it to grow in clumps. What's more, perennial ryegrass takes a while to mature and get established because its seedlings don't grow as vigorously.

For you, the lawn owner, the combination of factors above means one thing. If your turf comprises perennial ryegrass, you'll have to reseed bare spots yourself as soon as they emerge. Leaving the bald spots alone for long is not a great idea since weeds are more likely to establish themselves in unhealthy, sparsely growing lawns. Here's how to reseed perennial ryegrass bald spots quickly and effectively.

The good thing about perennial ryegrass is that you can seed it any time between the last and first frost date of the year. This means you don't need to wait to get rid of the bald spots on your lawn. Before you overseed the spots, you'll have to prepare them thoroughly. Mow the area around them to the same height you'd mow to in the spring. Then, remove the dead grass from the bare spots. To make the soil more conducive to new turf growth, rake the topsoil layer well, and then even out the surface so it's nice and smooth. If you were planning to apply pre-emergent herbicides to adjacent lawn areas around the same time, hold off on doing so for now; otherwise, you run the risk of keeping the ryegrass from germinating.

Now, the bald spots are ready for overseeding. This lawn seeding technique is simple. Start by broadcasting the seeds over the bare spots with your hand. Follow the seed manufacturer's instructions to make sure you're applying the right quantity. Once you've covered all the bald spots, top-dress them with a half an inch or so of soil — doing so will help keep the seeds from drying out. If your bald spots are situated on a slope, you can top dress them with a moisture-retentive mulch to keep the seeds secure. 

Next, all that's left is proper irrigation. Be sure to water your perennial ryegrass seeds evenly on a daily basis until the seedlings sprout to the optimal mowing height of 2 to 3 inches.