Posted 23 January 2012. Applied Turfgrass Science.
Bluegrass, Fescue (Over)Seeding Season Can Start Now
Source: Kansas State University Press Release. www.ag.ksu.edu
Olathe, Kansas (January 19, 2012)--In a break with long long-term trends, fall 2011 in Kansas wasn’t a great time to start or overseed a tall fescue or Kentucky bluegrass lawn.
“Normally, Mother Nature helps out with seed germination, but last fall we didn’t get any help. I saw poor germination in irrigated lawns and zero germination in non-irrigated lawns,” said Rodney St. John, turfgrass horticulturist with K-State Research and Extension.
Homeowners who got such results now have three options, St. John said. They can wait to reseed in fall 2012. They can plan to seed this spring. Or, they can get outdoors ASAP and try dormant seeding.
For homeowners, dormant seeding is the least favorite approach, because it’s timed for when the weather is cold -- too cold for seed to germinate. In Kansas, that generally means between December and February.
As with any turf-seeding approach, however, good seed-soil contact is important during winter. So, St. John generally recommends homeowners choose one of the following to achieve that contact:
• Spread seed by hand after a light snowfall of less than 1 inch (i.e., when you can still see the lawn’s bare spots). As the snow melts, it will bring the seed into good contact with the damp soil.
• Or, sow when the soil is moist and freezing weather is in the forecast. Freezing creates little bubble-like pockets in wet, bare soil – pockets that are perfect for catching and holding seed. When the soil dries later, those soil “bubbles” will collapse, covering the seed.
• Or, if soil is fairly dry and not frozen, rent and use a core aerator or vericutter. Then broadcast the seed.
“With good soil contact, the seedlings will emerge in early spring. If we have typical cool, damp weather then, the seedlings may not need any care until they’re tall enough to mow,” St. John said. “Homeowners rarely try the approach to seed an entire lawn, but it’s hard to beat as a low-stress way to fill in some thin or bare spots.”
Crabgrass prevention can be a problem, however, for both dormant- and spring-seeded turf. Most crabgrass preventers will kill turf seedlings until the new grass has grown enough to merit mowing three times – i.e., it has become well-established with roots that extend below the treatment zone.
“The two exceptions on the crabgrass preventer market now have different advantages, if you choose to use them,” the specialist said. “You can apply siduron – found in the product called Tupersan – even before seedlings begin to emerge in newly planted areas. It’s a good product, but it can be hard to find. Siduron won’t last as long or tend to be as effective as the other choice, but it’s safer on new grass seedlings.
“That second choice is dithiopyr or Dimension -- found in Hi-Yield Turf and Ornamental Weed and Grass Stopper. It becomes useful two weeks after fescue, bluegrass or perennial ryegrass germinate. But, you can apply it up to four weeks after crabgrass germinates – about the time that grassy weed becomes visible. And, it remains effective for about six weeks.”
For spring and fall lawn seeding, the steps are basically the same, St. John said.
Any county or district Extension office can help homeowners with any needed soil tests, variety recommendations and how-to information. In addition, K-State’s publication “Planting a Home Lawn” is available on the Web. St. John’s video “Overseeding Your Lawn” is also available.
He said the big differences between planting tall fescue or Kentucky bluegrass in spring or fall have to do with the likely weather.
For example, success in spring lawn seeding often comes down to planting early enough – March or early April. This gives the seedlings time to become well-established before the growing season’s hot weather and weed competition begin.
Planting early can be difficult, however, because spring tends to be a somewhat slushy, rainy season, St. John said. Working a wet planting bed is out. Doing so can destroy the soil’s structure – making it as hard as a compacted playing field. Adding insult to injury, follow-up rains can then lead to seed erosion.
“Last year was an exception. On average, though, fall gives you by far the best odds for seeding or overseeding a cool-season turf successfully,” the specialist said. “Typically, the weather is better, and it soon will be cooling off, not getting hotter. In turn, the weed pressure is dying down. Tall fescue and Kentucky bluegrass are starting their natural fall growth spurt.
“Fall also is the absolute best time to fertilize these grasses – which, at lower rates, can help turf seedlings along. With an application in September, you’re helping the turf strengthen up and prepare for winter. With another meal in November, you’re developing a denser lawn that will green up earlier the following spring.”
St. John would not recommend waiting for fall now, however, if homeowners are dealing with bare dirt.
If left unplanted, the weeds that need pulling/spraying will be obvious. Plus, homeowners will have plenty of time to both work and improve the soil before fall lawn-seeding time begins.
“For months, however, homeowners will also be facing the very real risk of soil erosion,” St. John said. “Getting at least some grass to grow in spring is better than having no grass -- bare soil -- until fall.”
Rodney St. John