The benefits of overseeding

A private residence before overseeding.
The same yard 15 days after seeding with SOS 211.

Is overseeding one of your offerings to clients? If not, you might want to consider it. Overseeding is very common for golf courses and sports fields, but isn’t used as frequently by landscape and lawn care professionals in many parts of the country. Overseeding is usually thought of as seeding a cool-season grass over a warm-season grass to provide green cover during the colder months. It can also include overseeding bare or worn spots in a cool-season turf to dress it up.


Bermudagrass, zoysia and St. Augustine are warm-season grasses that turn brown and dull after a frost or during cool winter days. In many parts of the country there are reasons to maintain green color beyond the warm season. It may be for aesthetics on high-profile commercial establishments or private residences. In Bakersfield, Calif., Bob Wheaton, owner of Certified Landscape Maintenance says, “Almost 100 percent of our customers want overseeding. We’ve been doing it for years.”

Apartment complexes, condominiums, townhouses and single-family homes that are for rent or for sale have much better curb appeal if the lawns look good. Research suggests that a properly maintained landscape can add up to 15 percent of a property’s value.

Lawns that are mixtures of warm and cool-season grasses are also candidates for overseeding. Instead of splotches of brown bermuda or zoysia and green spots of fescue, bluegrass or other cool-season grasses, your clients can have green turf throughout.

Another advantage of overseeding for the lawn care professional is that a growing lawn needs mowing and other attention. Greg Plahn, owner of Plahn Landscaping in Bakersfield, Calif., says, “If my clients want green growing grass year-round, I can provide and keep my employees busy all year. It’s a win-win for everyone.”

Grass Seed Germination Periods
Turf species Days to germinate
Annual Ryegrass 3 – 7
Bermudagrass (seeded) 10 – 30
Fine Fescue 14 – 21
Intermediate Ryegrass 5 – 10
Kentucky Bluegrass 7 – 30
Perennial Ryegrass 5 – 10
Tall Fescue 7 – 15

Planning for overseeding

Overseeding can be done at anytime, as long as the seed can be kept moist from the point of seeding through germination. Fall is the best time for seeding, and spring is OK, but if a client has a summer party or wedding, and their lawn needs some filling in, overseeding can be used. Plahn says, “We are frequently asked to overseed properties for special events, and June and July are especially good months for this. The planners want the best lawn possible for all the weddings and graduations, and the bermuda is still mostly dormant.”

The time between seeding and the need for establishment is mostly determined by the germination requirements of the seed. You need to decide what seed you are going to use and how long it is going to take for it to germinate to know how soon it needs to be seeded and how long it is going to have to be watered. Plahn says, “I like to have a month between seeding and the event. The lawn is going to look much better after at least two mowings, but with the right seed, I can get by with a couple of weeks if necessary.”

For best results with overseeding warm-season grasses, you want to overseed five to six weeks before the expected first frost. In this situation, make sure the cool-season grass is established before the warm-season grass goes dormant and browns out.

Transitioning back

If overseeding a warm-season grass with a cool-season grass, there are several things you need to know: what the client expects when it comes time for the warm-season grass to again take over, how you are going to assist that transition and how you are going to charge for it. The transition can be relatively easy or somewhat complicated, depending on a number of factors. Weather is a big one. The longer it stays cool in the spring, the more the cool-season grass in going to hang on. The sooner it gets warm, the sooner the warm-season grass will take over. Seed choice and cultural practices also will have a bearing. Getting the cool-season grass established can be easier than re-establishing the warm-season grass.

Annual ryegrass has usually been avoided for overseeding because of its lighter green color and straggly growth habit, but Dr. L. R. Nelson at the Texas Agricultural Experiment Station has bred a variety that is considered a turf-type annual ryegrass. It is more compact and a darker green than common annual ryegrass. Named Panterra, it is available through Barenbrug USA seed suppliers. Barenbrug has combined Panterra with some of their proprietary perennial ryes in various mixtures that they call Super Over Seeding (SOS).

A turf-type annual rye will generally transition out better than a perennial. When the weather gets too hot, and the bermuda starts to grow, the annual dies out. In some cases, chemicals are needed to transition out some of the perennial grasses.

Steve LeGros, consultant with Turf & Dirt, Inc., central Pennsylvania and Hagerstown, Md., says, “I have had instances where I’ve recommended Panterra and it has needed mowing three days after seeding. The shorter time you have between seeding and growth the less water you are going to need.”

Steve Trusty is a partner in Trusty & Associates, a communications and market research firm in Council Bluffs, Iowa. He has been worked in the green industry for over 40 years.