What's the best grass mixture for a western Oregon lawn?

Last Updated: 
August 4, 2008

CORVALLIS - When faced with the task of establishing a new lawn, people want to know the best kind of grass to plant. Tom Cook, turf specialist at Oregon State University, is asked about this a lot.

"I rarely give the same answer twice, because the best grass depends on the site, the owner and a dozen other variables," Cook said.

But hedging aside, Cook says there are several basic grass mixtures that will cover most situations. He has outlined them in his publication, "Practical Lawn Establishment and Renovation" (EC 1550), published by the OSU Extension Service.

Below are just a few grass seed mixtures that Cook recommends for western Oregon lawns.

"The percentages of mixture components are not sacred," said Cook. "You have to be flexible in shopping because every supplier has a different idea of what they want to sell you. The key is to study the label and go for the contents, not the price or the hype."

For general turf on sunny sites:

A mix of 70-80 percent perennial ryegrass and 20-30 percent fine fescue will make a lawn that is rugged, will tolerate some shade, requires medium to high fertility initially to look good, and is fairly easy to cut, says Cook.

"Mixtures like this start fast and quickly give a functional lawn," he pointed out. "They tend to be hungry for the first year or two since they are initially dominated by perennial ryegrass. By the third year, the fine fescues begin to dominate, particularly if you have not fertilized regularly. This lawn will be susceptible to red thread."

A mix of 60 percent perennial ryegrass with 20 percent fine fescue and 20 percent colonial bentgrass will produce a climax lawn that is dominated by bentgrass within two years from planting.

"Its strength is good turf quality fall through spring, low fertility requirement and long term persistence," explained Cook. "It works best when mowed to no higher than two inches tall and is well-suited to mulching mowers. This mix is available from some retailers in the Portland area, but will not be found in most garden centers."

A mixture of 50 percent perennial ryegrass and 50 percent Kentucky bluegrass creates a lawn that needs relatively high fertility to look its best, said Cook.

"And it requires sun," he added. "Plan on mowing (when the grass is) at one-and-a-half to two inches high – and irrigating regularly. You probably won't find this mix in the stores, but for people who like the bluegrass look it's a pretty good mix. Initially dominated by ryegrass, the bluegrass shows up in the second or third year. Either of these grasses planted alone tends to be invaded by other grasses rather quickly which ruins the appearance of the lawn. Mixed together, both grasses hold up better. In our trials, this mix was stable after five years."

A mixture of 50 percent perennial ryegrass, 25 percent Kentucky bluegrass and 25 percent fine fescues or similar mixtures are common in nurseries and discount stores, said Cook.

"This mixture may sound like the answer to everyone's prayers," says Cook, "but we've found the fine fescues don't blend well, and the lawn looks patchy."

For general turf on shady sites, Cook recommends a mixture of 70 percent fine fescue and 30 percent perennial ryegrass. He says it is an easy lawn to maintain with medium to low fertility, occasional irrigation, and mowing at about two inches.

"This mix takes advantage of the natural shade tolerance of the fine fescues and the rapid establishment of the perennial ryegrass," he said. "Fescues do better if the soil is fairly dry with good air movement. In wet shady sites typical of much of western Oregon, the fescues get riddled with fungal diseases."

For more information on home lawn care, check out these publications from the OSU Extension Service on line.

  • Fertilizing Lawns (EC 1278) (recently revised)
  • Necrotic Ring Spot on Turf in Oregon (EC 1462)
  • Conserving Water in the Garden: Landscape and Lawn Care (EC 1531)
  • Controlling Moss in Lawns (FS 55)
  • Practical Lawn Establishment and Renovation (EC 1550)
  • Maintaining a Healthy Lawn in Western Oregon (EC 1521)
  • If you don't have access to the web, write for a catalog and order form for printed versions of these publications from: Publication Orders, Extension and Experiment Station Communications, OSU, 422 Kerr Administration Bldg., Corvallis, OR 97331-2119. Or call 1-800-561-6719 and request a catalog.

    Author: Carol Savonen
    Source: Tom Cook