March 1, 2000 | By: Aimee D. Heald
LEXINGTON, KY.

The drought and heat of 1999 was rough on many Kentucky lawns. Most turf damage occurred on south or southwest-facing slopes, on lawns with heavy clay or very shallow soils, to newly laid sod that was not watered sufficiently, and in the shade of some water-loving trees. The problem was compounded by the drought continuing into the fall, thus preventing fall seeding or renovation during the optimum time for seeding grasses in late August and September.

"If a lawn area has some turf but the stand is thin, maybe 10 plants per square foot, reseeding may not be necessary," A.J. Powell, turf specialist for the University of Kentucky College of Agriculture, said. " Also, if reseeding was attempted last fall and some grass is present, reseeding again may not be necessary. But, you will need to ‘grow-in' the grass by applying nitrogen during late February - early March. Apply about one pound of nitrogen per 1000 square-feet. For normal lawn maintenance, we do not usually recommend this spring nitrogen but with young or thin turf, the roots cannot take up enough of the inherent soil nitrogen for ‘grow-in'."

The best spring seeding time is from about mid-February through mid-March. Germination will not likely occur prior to about March 20, but this varies considerably. The earlier it germinates, the better stand you will get. Spring freezes do not hurt young seedlings.

Powell emphasized that early establishment is important to get maximum cover prior to weed growth and to get maximum root growth prior to high summer temperatures and drought.

"Crabgrass pre-emerge herbicides are normally applied between mid-February and mid-April. If you plan to reseed, don't use the normal herbicide and timing," Powell said. "Even broadleaf weed herbicides applied shortly before or after seeding may reduce seedling establishment." Most old lawns originally were established with Kentucky bluegrass but within the last 15 to 20 years, most seeded lawns and some sodded lawns have been established with turf-type tall fescue. Also, some fine leaf fescue lawns have been established in shady sites and there are some turf-type perennial ryegrass lawns.

For the newly seeded area to blend with the surviving portion of the lawn, it is best to seed the same grass species already present. Powell said this poses a problem with Kentucky bluegrass lawns because Kentucky bluegrass germinates very slowly in the spring, has very low seedling vigor, and often the shallow-rooted grass will not survive the following summer.

If bluegrass is seeded, good moisture must be provided during establishment and also during the following summer.

Many Kentucky bluegrass lawns already have numerous tall fescue clumps or have other serious weed problems. It certainly would be preferred to seed tall fescue into these lawns. In fact, it would be better to renovate the entire lawn with tall fescue, not just the bad spots. See UK publication AGR-51 for whole lawn renovation or go to http://www.uky.edu/Agriculture/ukturf to find seeding rates and variety recommendations. Powell recommended many methods for renovation of a post-drought lawn (SEE SIDEBAR). He stressed that to get good establishment, you need good soil to seed contact.

After renovating the lawn, it's important to encourage quick germination and sod establishment.

"For quickest establishment, water immediately after seeding and keep the surface moist until germination is complete," Powell said. "Drying winds and intermittent rainfall can be severe enough during some spring seasons to cause failure if irrigation cannot be applied."

Spring seedlings will seldom develop into mature plants unless extra nitrogen is applied soon after germination. Apply about one pound of nitrogen per 1,000 square-feet. Although this nitrogen may increase crabgrass competition, it is necessary to get root growth and plant maturity. Do not let new seedlings grow tall prior to initiating mowing. If you normally are mowing the lawn at two inches for example, mow the new grass at that same height. Never remove more than about one-third of the grass height with each mowing.

By following some simple steps and giving a post-drought lawn extra attention, Kentucky can have beautiful lawns in the new millennium. SIDEBAR

Methods of Rennovating a Post-Drought Lawn

Slit Seeding/Power Seeding. Many commercial lawn companies renovate lawns with power seeders, i.e. a self-propelled machine that cuts slits through the surface organic matter and into the soil, then drops seed into the slits. These power seeders can sometimes be rented from rental companies, however they are not easily maneuvered on sloping lawns. When seeding with tall fescue or perennial ryegrass, it is best to seed about one pound per 1,000 square-feet for each pass across the lawn. Additional seed can be broadcast on the surface, then followed by an additional pass over the lawn with the power seeder. This gives improved soil to seed contact and better over-all coverage.

Vertical Mowers/Dethatchers. Dethatching machines can also be rented and used to loosen the dead grasses/weeds, and also used to make shallow grooves in the soil surface. The dethatcher may need to cross the area several times, in different directions, to disturb the soil sufficiently. Use dethatchers equipped with blades or knives; those equipped with spring-tines will not give sufficient grooving and loosening of the soil surface. If a large amount of organic material or thatch is dislodged by the thatching machine, it should be removed and discarded. A small amount of organic matter left on the surface will act as a mulch and help conserve moisture.

After dethatching, evenly broadcast the seed over the lawn, then go over the lawn again with the dethatcher or a hand rake. This will help to get better seed : soil contact.

Topdress Seeding: Small areas can be renovated by hand raking some of the dead organic matter off the surface, broadcasting the seed, then covering the seed with about 1/8th of an inch of good garden soil, sand or peat.

Core Seeding: Renovation is seldom successful when an aerifier (coring machine) is used to make small holes in the lawn and seed is then broadcast over the surface. A very small portion of the seed makes good soil : seed contact. If using a coring machine, traverse the lawn several times, making 20 to 30 holes per square foot. With soil cores redeposited back on the surface, improved soil : seed contact is made and the renovation can be successful.

Sodding. The quickest repair method is to remove the dead sod with a sod cutter or hoe, loosen the soil surface, lay the sod and water. A sod cutter can often be rented and used to remove the old/dead sod. Quality tall fescue and Kentucky bluegrass sod can be purchased at some garden centers or local sod farms.

Contact: 

A.J. Powell 606-257-5606