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Gardening Q&A: Cool-season turfgrass species performs best in Western Pennsylvania
Saturday, September 23, 2000 By Sandy Feather, Penn State Cooperative Extension Agent
Q. I am putting in a new lawn and want to use the type of turfgrass that best suits my needs. Can you tell me the strengths and weaknesses of each type of turfgrass?
Send questions to Sandy Feather by e-mail at slf9@psu.edu or by regular mail c/o Penn State Cooperative Extension, 400 N. Lexington St., Pittsburgh 15208. Due to volume of mail, personal replies cannot be provided.
A. Turfgrasses are divided into cool-season and warm-season species. North of the Mason-Dixon Line, we grow cool season species; south of the line, warm season species perform best. As those names imply, cool season turfgrasses perform best during the cooler times of the year, typically spring and fall. They tend to brown out during the heat and drought of summer and stay green during the winter. Conversely, warm season turfgrasses perform best during hot weather. They tend to turn brown with the first frost and stay that way until warm weather arrives.
We grow cool season turfgrasses in Western Pennsylvania. These include Kentucky bluegrass, rough bluegrass, perennial ryegrass, fine fescues and tall fescue. Zoysia grass is the only warm season species that is winter hardy in Pennsylvania. Except in extreme southeastern Pennsylvania, it will stay straw brown for six months out of the year. For that reason, most turfgrass specialists do not consider zoysia an acceptable option in Pennsylvania.
Kentucky bluegrass (Poa pratensis) is considered the Cadillac of turfgrasses for our area. It is used for home lawns, parks, athletic fields and commercial grounds. Kentucky bluegrass is well adapted to our clay soils and has a fine-to-medium texture and medium-to-dark green color. It spreads by underground stems (rhizomes) and therefore has excellent ability to recover from drought, insect and disease injury. Kentucky bluegrass is cold-tolerant, wear-tolerant and is moderately heat- and drought-tolerant. It goes dormant during periods of heat and drought and recovers quickly with rain and cooler temperatures. It performs best in full sun and well-drained soil. There are several varieties of Kentucky bluegrass that are shade-tolerant, including A-34 (Bensun), Bristol, Eclipse, Glade, Nugget, Touchdown and Victa.
On the downside, Kentucky bluegrass requires a higher level of fertility (2 to 4 pounds of nitrogen per 1,000 square feet throughout the growing season) than other cool season turfgrasses. Because it spreads by rhizomes, it has the potential to build up a significant thatch layer quickly. It is also slow to germinate, up to 30 days. Some of the diseases Kentucky bluegrass is susceptible to include leaf spot, stripe smut, dollar spot, necrotic ring spot and summer patch. In home lawn situations, selecting resistant varieties and using proper cultural methods are preferable to fungicide applications to control these diseases.
Kentucky bluegrass is an important constituent of most mixtures of turfgrass varieties. You should use 2 to 3 pounds of seed per 1,000 square feet to start a new lawn.
Rough bluegrass (Poa trivialis) is closely related to Kentucky bluegrass. It has a light green color and spreads by above-ground stems (stolons). Rough bluegrass is highly shade-tolerant and is the only turfgrass species that will tolerate damp shade. When grown in full sun, it tends to brown out during summer heat and drought. Rough bluegrass can be invasive. It is not generally used in mixes with other turfgrass species because of its lighter green color and tendency to form noticeable patches. If you want to grow turfgrass in damp shade, rough bluegrass is the answer. Otherwise, it is not a desirable addition to your lawn.
Perennial ryegrass (Lolium perenne) has become very popular for home lawn use in recent years. It is also used for athletic turf, parks, golf courses and commercial grounds. Perennial ryegrass has good dark green color and fine-to-medium texture. It is a bunch-type grass that does not spread by rhizomes or stolons. Therefore, it builds thatch much more slowly than Kentucky bluegrass. Perennial ryegrass germinates quickly, roughly five to seven days under good conditions. It is wear- and heat-tolerant. Perennial ryegrass performs best in full sun and well-drained soil. It prefers moderate-to-high fertility, 3 pounds of nitrogen per 1,000 square feet throughout the growing season.
On the downside, perennial ryegrass can be severely injured by extended drought or winter cold when there is no snow cover (a common occurrence here). Since it is a bunch-type grass, it has lower potential to recover from injury than Kentucky bluegrass. Older varieties of perennial ryegrass have a stringy texture much like celery and do not cut well, particularly if your mower blade is dull. Some of the diseases perennial ryegrass is susceptible to include Pythium blight, brown patch, dollar spot, red thread and rust. While most of these can be controlled by varietal selection and proper cultural practices, Pythium requires expensive fungicide applications. It can devastate a solid stand of perennial ryegrass in a short time.
Perennial ryegrass is an important constituent of mixtures of turfgrass varieties. You should use 4 to 5 pounds of seed per 1,000 square feet to start a new lawn.
Do not confuse perennial ryegrass with annual ryegrass. Annual ryegrass is used as a cover crop in the vegetable garden, a nurse crop to stabilize hillsides, or a quick, inexpensive cover. It is great to get you up out of the mud during construction projects. It is not desirable to have annual ryegrass comprise a large percentage of a permanent grass seed mixture. It is an annual that will only grow for a season.
Fine fescues (Festuca species) are very fine-textured turfgrasses. They include creeping red fescue (Festuca rubra), Chewings fescue (Festuca rubra variety commutata), hard fescue (Festuca longifolia) and sheep fescue (Festuca ovina). They are used for home lawns, commercial grounds, golf course roughs and parks. They exhibit medium to dark green color. Fine fescues tolerate low fertility, acidic soil, drought and shade. Like Kentucky bluegrass, they go dormant during periods of heat and drought and recover quickly with rain and cooler temperatures. They prefer a low level of fertility, 1 to 2 pounds of nitrogen per 1,000 square feet throughout the growing season.
On the downside, fine fescues do not tolerate hot, humid conditions well. They do not tolerate poor drainage, heavy traffic or high levels of fertility. Chewings and creeping red fescue spread by rhizomes and can build significant thatch. Some of the diseases fine fescues are susceptible to include leaf spot, dollar spot and red thread. Varietal selection and proper cultural practices are preferable to fungicide applications to control these diseases on home lawns.
Fine fescues are commonly used in turfgrass mixtures and should be sown at a rate of 4 to 5 pounds per 1,000 square feet.
Tall fescue (Festuca arundinacea) is a tough, durable turfgrass for home lawns, commercial grounds, parks, playgrounds and athletic fields. It is often used in low-maintenance situations such as reseeding strip-mined areas, utility rights-of-way and highway medians. Old varieties such as Kentucky 31 are light green and very coarse and do not combine well with other species of turfgrass. The newer turf-type tall fescues have much better dark green color and finer texture, while maintaining excellent drought and wear tolerance as well as moderate shade tolerance. Tall fescue is usually grown alone rather than mixed with other species of turfgrass. Tall fescue is a bunch-type grass that builds thatch more slowly than Kentucky bluegrass. It performs well with 2 1/2 to 3 pounds of nitrogen per 1,000 square feet throughout the growing season.
On the downside, tall fescue is slow to germinate, up to 30 days. It can be damaged by winter cold when there is no snow cover. Since it does not spread by rhizomes, tall fescue does not have the ability to recover from injury that Kentucky bluegrass does. Some of the diseases tall fescue is susceptible to include brown patch, Pythium blight and red thread. With the exception of Pythium, varietal selection and proper cultural practices are preferable to fungicide applications to control these diseases on home lawns.
Tall fescue should be sown at a rate of 6 to 8 pounds per 1,000 square feet.
To avoid a monoculture situation, we usually grow mixtures of different types of turfgrasses. That way, if a disease wipes out a portion of your lawn, you will have the remaining types of turfgrass to carry on. A very common recommendation for our area is called Penn State Mix, which is a mixture of varying percentages of Kentucky bluegrass, perennial ryegrass and fine fescue. The name comes from the fact that Penn State has been recommending such a mix for home lawn use for many years, not because Penn State sells grass seed (it does not). Even if you wish to have a lawn comprised of one species of turfgrass, e.g., Kentucky bluegrass, be sure to use a blend of different varieties. Each will have different disease resistance and cultural tolerances.
Here are some suggestions for home lawn seed mixtures:
For open, sunny situations: 100 percent Kentucky bluegrass; 100 percent turf-type tall fescue; or 80-90 percent Kentucky bluegrass and 10-20 percent perennial ryegrass.
For a mix of sun and shade: 40-60 percent Kentucky bluegrass, 30-40 percent fine fescue and 10-20 percent perennial ryegrass.
For heavy shade and well-drained soil: 100 percent fine fescue.
For heavy shade and poorly drained soil: 100 percent rough bluegrass
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