Perennial ryegrass is one grass that is known both to warm- and cool-season grass areas. Perennial ryegrass is the first species to germinate in cool-season grass mixes. In warm-season turf, count on it for medium to deep green color in the winter months. Homeowners in northern areas of the country can plant it as a monostand (single-grass lawn) as well.
Perennial ryegrass at a glance
Classification: Cool-season grass
Spreads by: Bunch-type grass
Shade tolerance: Low — prefers full sun
Drought resistance: Low (summer dormancy in some areas)
Foot traffic tolerance: High, but poor recuperative ability
Maintenance needs: Moderate mowing requirement, depending on cutting height (lower cutting heights require more frequent mowing)
Mowing height: 2-3 inches
Potential for disease: High, especially in areas with hot, humid summers
Soil pH: 6-7
Soil type: Good drainage, high fertility
Other notes: Most often mixed with Kentucky bluegrass and fine fescue in a cool-season mix; well known for its excellent striping ability, low mowing tolerance (reel mower fans, this one’s for you), and rapid germination rate (four to seven days). Needs moderate levels of fertilizer.
What is perennial ryegrass?
Although perennial ryegrass is most often used in a mix with Kentucky bluegrass and fine fescue, it is possible to have a monostand in some climates. This grass germinates in less than a week (four to seven days) and produces a beautiful, medium to dark green lawn in ideal conditions. For homeowners who don’t mind a high-maintenance turf and want a cool-season perennial grass they can cut often and low with a reel mower, this high-maintenance monostand will fit the bill.
Perennial ryegrass has relatively good resistance to wear once it is established as a mature turf, even though as a bunch grass it is not able to self-repair (which other grasses do via underground or above-ground stems). Another feature that makes this grass attractive to lawn aficionados is its excellent striping ability. Perennial ryegrass has a waxy coating on the leaves that makes lawn stripes stand out even more.
So, what’s the downside? Perennial ryegrass may die or suffer injury if winter temps are too low or summer temps are too high. However, as a cool-season grass, it is possible to overseed the lawn in fall and spring if death or damage occurs. In addition, gray leaf spot used to be more of a problem than it is today thanks to improved cultivars; however, this and other fungal diseases continue to plague this turfgrass, especially in hot, humid summer conditions.
(Note: In this article, we’ll concentrate on perennial ryegrass as a monostand.)
Pros and cons of perennial ryegrass
Whether you live in a warm-season or cool-season grass zone, check out these strengths and weaknesses to know if perennial ryegrass is right for you:
Pros
✓ Not prone to thatch
✓ Reel mower friendly
✓ Fast germination time
✓ Excellent striping ability
✓ Medium to dark green color is desirable for some homeowners
✓ Soft grass to walk on barefoot
Cons
✗ Low tolerance to shade
✗ Low ability to recover from damage (no stolons or rhizomes)
✗ Low drought and heat tolerance
✗ Susceptible to fungal diseases, especially in climates with hot, humid summers
How to establish perennial ryegrass
If you want to establish perennial ryegrass as a monostand, there are a few things to consider before you buy the bag of seed.
- Buy only improved, turf-type varieties
Make sure your seed is not a common or forage perennial ryegrass. These do not produce a high-quality lawn.
- Talk to a local expert
Contact your local Cooperative Extension specialist to ask if a perennial ryegrass monostand is a good idea in your area. Perennial ryegrass is susceptible to winterkill and summer disease pressure (it prefers moderate winter and summer seasons), so the areas in which you can grow a monostand successfully are limited. (It also may grow well in high elevations, above 2,000 feet.) Otherwise, buy a mix of different cool-season grass species to give your lawn a better chance to thrive.
- Research different cultivars
Each cultivar has different tolerances to stress, diseases, and temperature, so research which cultivars work well for the stresses that are common to your location. Also, consider regenerating perennial ryegrass or RPR. There are a few cultivars of this new grass type that have small stolons (above-ground stems), which have made these an attractive option for sports turf managers who want better traffic tolerance from their cool-season turf.
Once you’ve done your homework, seed perennial ryegrass at 3 to 5 pounds per 1,000 square feet. Plant cool-season lawns in the late summer or early fall, during its natural growth period. Once you’ve put the seed down, rake it in to make sure you have good seed to soil contact.
Then, keep the soil bed moist with one to three light waterings per day (depending on your climate and soil type). The key is to keep the soil moist but not soggy, making sure the top ½ inch is constantly moist. Once the perennial ryegrass germinates (four to seven days), water less often but more deeply each time, again, making sure water doesn’t run off of the soil.
Once the grass reaches 1 inch tall, start to water every other day, slowly transitioning to your normal watering schedule as the grass reaches its mature height. For more details, learn “How to Plant Grass Seed in 10 Simple Steps.”
Sod is available in some states but is less commonly used. Since perennial ryegrass germinates so quickly, weeds aren’t an issue, so it makes more sense for homeowners to seed this grass.
How much does perennial ryegrass cost?
Perennial ryegrass seed: Costs vary widely by brand and supplier; a 5-pound bag ranges from about $19 to $44
Perennial ryegrass sod: Costs between 40 cents and 85 cents per square foot
Caring for perennial ryegrass
Mowing
As a monostand (a one-grass lawn), mow from 2 to 3 inches for most home lawns. At lower mowing heights (under an inch), you’ll need a reel mower, which is uncommon for most home lawns. Taller mowing heights can be accomplished with a standard rotary mower.
Keep in mind that the lower you mow, the more often you’ll mow since you’ll want to remove only ⅓ of the grass blade per mow. A taller cut means less mowing.
Don’t forget to leave the grass clippings on the ground as you mow (as long as the grass is healthy and disease-free). This reduces your fertilizer each year by up to 30%.
Water
Perennial ryegrass likes to stay well watered, even in summer. If it goes into summer dormancy, recovery is slow, and dormant grasses are susceptible to disease, pests, and weeds. So, plan to apply at least 1 inch of water per week (if it doesn’t rain) during the summer to keep the lawn green and growing.
Fertilization
Perennial ryegrass requires 1-5 pounds of nitrogen per 1,000 square feet per year. As with most cool-season lawns, apply most of your applications in the late summer to early fall and some in spring after green-up.
Dethatching and aeration
Thatch is generally not a concern with perennial ryegrass.
If your soil compacts easily (not an ideal condition for this grass since it requires good drainage), aerate every fall.
Core aeration pulls cores of soil from the ground, opening up the roots for better air and water circulation. This creates a stronger, healthier root system, which means a stronger, healthier perennial ryegrass lawn.
Disease, insects, and weeds
Disease: Perennial ryegrass is susceptible to several turfgrass diseases, especially in hot summer weather. These are a few you may encounter:
- Gray leaf spot
- Dollar spot
- Brown patch
- Red thread
- Rust
- Pythium blight
To create a stronger perennial ryegrass lawn, choose a blend with several different cultivars in one mix. This increases the strength of the lawn against disease, drought, and other stresses.
And before you click “buy” on that fungicide, there are many other practices to take up first to prevent and treat fungus in your lawn. Here are a few to get you started:
- If you have a Kentucky bluegrass, fine fescue, perennial ryegrass mix, dethatch the lawn once thatch levels exceed ½ inch. Fungus tends to thrive in grass with high levels of thatch.
- Water in the early morning hours, before 10 a.m., to give the grass time to dry completely. Water only when the grass shows signs of drought stress (footprints that stay on the lawn, grass turning a different color, or blades that wilt).
- Remove clippings temporarily if you have a fungus problem. Once the fungus is resolved, you can continue to mulch the clippings into the grass and return those good nutrients to the soil.
- Aerate if you have compacted soil. Aeration strengthens the grass by allowing more light, air, and water at the root level. It also removes some thatch (though not as much as dethatching).
Insects:
- Billbugs
- Greenbug aphids
- Chinch bugs
Choose endophyte-enhanced varieties for the best insect resistance. Endophytes produce alkaloids that deter insects from feeding on the grass.
Pro Tip: If you have leftover seed, store it in a temperature-controlled environment. The endophytes lose their viability in hot storage conditions.
Weeds:
If you see weeds pop up in your perennial ryegrass lawn, there are a few options.
- Chemical control: Combinations of dicamba, 2,4-D, and mecoprop are safe for post-emergent weed control in established perennial ryegrass lawns. This chemical cocktail will control annual and perennial weeds that have sprouted in the lawn.
To prevent weeds from sprouting in the first place, use a pre-emergent herbicide in spring and fall before you see summer and winter annual weeds pop up. Temperatures can vary slightly by region, but in general, apply pre-emergents in spring when soil temps (not air temps) are 55 degrees and warming. In fall, apply pre-emergents when soil temps are around 65 degrees. Check with your state’s Extension Office for further details on the best time to apply.
- Natural approach: There are many products on the market for organic pre- and post-emergent weed control in perennial ryegrass lawns. There are also many organic home remedies such as horticultural vinegar, weed torches, and hand-pulling, among others.
Some information taken from Fundamentals of Turfgrass Management, 5th ed. by Christians, Patton, and Law
If you think a perennial ryegrass lawn may be right up your alley, contact one of our local lawn care professionals. They can help you select, install, and care for your grass so you can spend your free time doing what matters most.
Main photo credit: istock
