The best time to seed cool season grasses, such as Kentucky bluegrass and tall fescue, is between Aug. 15 and Sept. 15, so it’s time to get started!
Getting your seeding done as early as possible is really important, because each week of delay in seeding translates into two to four additional weeks required for the grass to mature in fall. It is critical to seed tall fescue no later than mid-September. Tall fescue seedlings take a longer time to develop cold hardiness, so get your seeding done early.
Fall is, in fact, the best time of year for seeding lawns due to a combination of factors. First, there’s less weed pressure than in spring and less rain in late summer making soil preparation easier to complete. Plus, the extended period of cool weather, usually with good rainfall, that occurs from September through late November is ideal for growth of cool season turfgrasses.
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Total Renovation: If you need to renovate the entire lawn, start by killing the remaining grass and weeds with glyphosate (RoundUp), then wait 10 to 14 days for the herbicide to take effect. Difficult weeds may need a couple applications to kill completely, so get started early. Next, mow the dead vegetation as short as your mower will allow and move on to soil preparation.
Overseeding: If you just need to fill in thinned areas and still have more than 50% good turf then overseeding is the answer. Skip the RoundUp, but mow the existing grass fairly short, 2.5 or 3 inches tall, to make the next step — soil preparation — easier.
Soil Preparation: Prepare the seedbed through aerification, making at least three passes over the lawn. You need to produce lots of bare soil, so the seed can make contact with it. Watering the lawn area a day or two beforehand will make aeration easier and allow the machine to take deeper cores.
Fertilization: Nebraska soils are rarely low in phosphorus, but turfgrass seedlings do benefit from a starter fertilizer high in phosphorus at seeding. Once the area is prepared, apply a starter fertilizer totaling 1 to 1.5 pounds of phorphorus per 1,000 square feet.
Phosphorus is the second number in the fertilizer ratio. For example, a 16-22-8 product contains 22% phosphorus. At 22% phosphorus, you would need to apply approximately 4.5 pounds of product per 1,000 square feet to supply 1 pound of phosphorus per 1,000 square feet.
Purchase high-quality blue- or gold-tag seed with a blend of three or four Kentucky bluegrass and/or turf-type tall fescue cultivars. Having a blend of cultivars broadens the genetic base of your turf for disease resistance. You get what you pay for in grass seed, so go for the most expensive seed you can find. The cost of seed is a minor expense when compared to the cost of establishment and maintenance for the life of the lawn.
Seed buying don’ts
1. Don’t buy seed in bulk bins when the grass species and cultivars are not listed. You don’t know what you’re buying and it may not be very high quality seed.
2. Don’t buy seed labeled VNS, meaning variety not stated.
3. Don’t buy routinely advertised grass seed.
4. Don’t buy seed containing annual ryegrass, “K31” fescue, “Kenblue” Kentucky bluegrass or “Linn” perennial ryegrass.
After preparing the area, use a drop spreader to apply the seed. Rotary spreaders are great for fertilizing, but not so great for seeding. Seed is too light to spread uniformly with a rotary spreader so purchase, rent or borrow a drop seeder. Divide the seed in half; apply the first half as you walk north to south, and the second half going east to west. This helps ensure even distribution.
Afterwards, rake the seed slightly to ensure good seed-soil contact. The full seeding rate for turf-type tall fescue is 6 to 8 pounds per 1,000 square feet, and two or three pounds for Kentucky bluegrass. When seeding into an existing lawn, the seeding rate can be cut in half.
Watering and mowing
Irrigate the seeded area two to four times a day during the first two weeks, depending on temperatures. Keep the top half-inch or inch of soil moist as the seedlings germinate. Taper off your watering schedule as the seedlings develop. As they approach mowing height, reduce the number of irrigations to two or three times per week, but water more deeply with each application to encourage deep root development.
Begin mowing as soon as possible. Mowing encourages tiller (secondary stem) development and helps new plantings thicken up quicker. It also keeps weeds under control while the new seedlings become established. Just be sure your mower blade is good and sharp!
If fall turfgrass seeding isn’t possible for you, then consider dormant seeding. With this method, the area is prepared in late fall, late September through November, but the seed is not distributed until after the growing season has ended. Plan to spread the seed anytime from mid- to late November through March. Your goal is to have the seeding completed and ready to germinate in spring when rain and soil temperatures are right. Watch for more information on dormant seeding in November.
For more information on lawn seeding, check out the following publications.
• Choosing Grasses and Buying Seed, UNL Turfgrass iNfo, https://go.unl.edu/grassselection
• Improving Turf in Fall, UNL Turfgrass iNfo, https://go.unl.edu/fallseeding
• Establishing Lawns From Seed, UNL Turfgrass iNfo, http://go.unl.edu/lawnseeding
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Sarah Browning is an extension educator with Nebraska Extension. To ask a question or reach her, call 402-441-7180 or write to her at [email protected] or 444 Cherrycreek Road, Lincoln, NE 68528.