Turf Care: Optimal Overseeding

Prep, seeds, and spreading methods.

Previously, Turf covered the fertilization aspects of overseeding. In this article, we look at further tips regarding preparation, grass variety, and method. Keep this on hand for Fall overseeding projects!

Overseeding is an easy way to fill in bare spots, improve the density of turf, establish improved grass varieties, and enhance a lawn’s color. For professional lawn care operators, overseeding can help instill trust in your customers since it’s a nuanced task that ideally yields very obvious results.

Yet achieving those obvious results can often stir up anxiety, or at least a lot of questions. Did I consider everything? Are the conditions just right? And while nothing is a sure thing, there are several practical steps you can take to make overseeding success more likely.

Getting The Turf Ready

Often, a seeding project is only as effective as your preparation. It’s like picking up the house before you vacuum, or sanding wood before you stain it. If you don’t start with the right conditions, you’ll face challenges in the results. While you can’t eliminate obstacles such as weather, shade, and foot traffic, there are steps you can take. Here’s a checklist contributed by Matt Shaffer, a world-renowned turf professional and director of Golf Course Operations Emeritus at Merion Golf Club in Ardmore, PA.

First, remove all debris from the turf, starting with mowing and bagging your grass.
Then dethatch the lawn, using a dethatcher. Set the machine so it is just at the soil line. The best way to check that is to do a pass and then cut a triangle out with a pocketknife to see how deep you are going.
Hand-rake the lawn.
Cut the lawn again, but set the mowing height ½” lower, and bag all the clippings. The lawn will look rough at this point, but do not water.

Then, you’ll want to decide if you should aerate. I personally always recommend aeration to loosen the soil and give water, air, seed, and fertilizer more of an opportunity to get into the soil. One way to determine if you should aerate normally or aggressively is to use the screwdriver test. Hold a screwdriver by the handle with the head pointed down, and at about waist height, gently toss the screwdriver down toward the ground. If it sticks easily, your soil is soft enough for typical aeration. If it bounces away and doesn’t stick, the soil is dry and compacted and might require more aggressive aeration.

Select The Right Grass

With the many varieties and grass seed mixes available, where do you even begin? Ultimately, proper seed selection comes down to your climate, so it’s difficult to recommend a specific variety. If you don’t know where to start, contact a local seed distributor; they will be able to give you an idea of what varieties and mixes will work best for you. It helps to consider these factors: cli-mate; shade; wear-and-tear; and color.

Climate. Is a cool-season or warm-season grass appropriate? With climate extremes, drought, and water shortages, properties in transition zones may consider rethinking old choices. According to a previous article in Turf, the California turfgrass industry has seen a major transition from cool-season grasses to warm-season grasses in recent years. This includes a growing demand for Bermudagrasses due to water-saving capabilities. A Fresno farm which once sold 80% fescue and 20% warm-season grasses now comes in with sales at 75% warm-season and 25% cool-season. Talk to other landscapers, area sod producers, and Extensions for the most up to date recommendations in transition zones.

Shade. How much sun your turf gets will play a big role in what kind of seed to use.

Wear-and-Tear. How much traffic are you expecting the turf to get? If it’s a front yard of an older couple that won’t use it much, it’s a much different story than a soccer field that has games all week long.

Color. Grass varieties come in all shades of green, so make sure you’re considering the color when choosing the seed. While pretty much all seed grows well in the sun, you’ll want to do some research to find the right shade-tolerant grass variety for your area.

Cost. Although tempting, saving a few bucks on cheap seed could cost thousands to your reputation—and ability to sell over-seeding services the following season. Seed is a long-term investment. Buy the good stuff for better germination, quality, and vitality. “When you really factor in your fuel, labor, machine time, and parts, putting seed down is the cheapest thing you can do,” comments Shaffer.

Method & Equipment

When it comes time to put seed down, there are several tools at your disposal depending on what you want to accomplish. Shaffer, again, has some tips on what equipment to use and how:

Put the first half of the seed down with a drop spreader.
Aerate the lawn in two directions.
Put the other half of the seed in an overseeder and go over the lawn in two different directions. Preferably in a diamond-shaped pattern.
Put a starter fertilizer down that has more phosphorus in it. Make sure your state does not have phosphorus restrictions. (Some states that reportedly do include: Illinois, Maine, Maryland, Michigan, Minnesota, New Jersey, New York, Vermont, Virginia, Washington, and Wisconsin.)
Irrigation should keep the seed damp, but not soaked. Set the irrigation system accordingly or tell clients to water in the early morning, the coolest time of the day.
When the grass germinates, wait until it develops a third leaf before cutting it. Give the plant a gentle tug to make sure it is rooted down. Make sure the mower blade is extremely sharp or it will rip and shred the new seedlings. At this time, start backing off irrigation requirements. And keep a close eye on the weather to ensure the grass doesn’t dry out too much at client properties that received overseeding services.

Although you can’t guarantee clients a perfect lawn after overseeding, you can stack the deck in your favor by following these tips. You’re likely to come out with better-looking, healthy grass that will serve as a testament to your abilities as a turf professional.

Scheffler is the senior product manager for RYAN. In business since 1946, RYAN manufactures durable, high-performance turf maintenance equipment. The company’s range of heavy-duty, commercial-built products has grown to include aerators, dethatchers, overseeders, and sod cutters.