CORVALLIS, Ore. – Lawn looking lackluster? Mid-August to early October is a sweet spot in the calendar year to sow fresh grass seed or replace an existing lawn throughout the state, according to Alec Kowalewski, turfgrass specialist for the Oregon State University Extension Service.
If you wait until November, you're too late – the next best bet to establish a new lawn comes around the following April to May.
"The problem is that when you get later into the year, annual bluegrass takes over," Kowalewski said. "If your turfgrass seed germinates late in the fall, it will not out-compete annual bluegrass, a very problematic, profuse weed due to our wet climate."
Wondering which type of turfgrass is best? If you live in western Oregon and full sun embraces your lawn, Kowalewski recommends perennial ryegrass. If your lawn lies in the shade or you don't irrigate much, fine fescues are a great choice, he said. But Kowalewski advised picking tall fescues if you don't water much and your lawn gets full sun.
"Fescues are very drought-tolerant," Kowalewski said. "Tall fescue is the most drought-tolerant and fine fescue is both drought- and shade-tolerant."
For eastern Oregon homeowners who deal with a significant amount of snowfall, Kowalewski suggested Kentucky bluegrass. But remember, it needs irrigation.
Science has not created a kind of turfgrass that stays green all year without any water – yet.
"Tall fescue is the closest thing to it," Kowalewski said.
To establish a new lawn, decide first whether you are completely redoing your lawn or freshening up scruffy-looking patches of turfgrass. If you're tearing out your old lawn, see the OSU Extension article Two ways to uproot your lawn.
If you're repairing an old lawn, first aerate it with a core-cultivating machine and seed the turfgrass into the existing lawn. It's a practice known as inter-seeding or renovation, Kowalewski said.
"The most important part is adding fertilizer while seeding," Kowalewski advised. "From now until the rainy season starts, you'll need to irrigate lightly every day to every other day to keep the grass moist. About one-tenth of an inch each time you water is adequate."
Select turfgrass-specific starter fertilizer. Perennial ryegrass will germinate in about 7-10 days and will establish about deep roots in 2-3 weeks. Kentucky bluegrass, tall fescue and fine fescue will germinate in about 21 days and take about two months to take root. When grass has developed strong enough roots, it's time to start mowing it and playing on it.
Want to support Oregon grass seed growers with the purchase of your new lawn?
"The cool thing is that most of the grass available on the market is grown right here in Oregon," Kowalewski said.
For more information, see the following OSU Extension guides: