Lawn Overseeding

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The fall months of September and October are ideal for overseeding cool season lawns. Whether you tried in the spring and didn’t get the results you wanted; or you’ve had disease (i.e. brown patch) or insects (i.e. grubworms) which have thinned your turf, now’s the time to remedy those problems. It’s the perfect time to start a brand new lawn, too, using most of the “Ten Steps to Successful Overseeding” listed below.

Always start with good seed, because the quality of the seed determines the quality of your lawn. Look for a seed with a high germination percent. (This indicates how much grass seed will actually sprout.) Also, check the label for the percent of weed seed and other filler. Even 1% weed seed in a 25-lb. bag of grass seed translates into a QUARTER POUND OF WEED SEEDS. That’s a lot of weeds to contend with in your quest for the perfect lawn.

Be patient when overseeding, If you see a few thin spots in your lawn going into winter, don’t fret … and DON’T OVERSEED AGAIN YET. Keep your lawn fertilized on schedule and you’ll be surprised how it fills in next spring.

Next fall, if spots remain a little thin, lightly overseed at that time, keeping in mind that a little seed is better than a lot.

STEP 1. Before you begin, make sure the soil is evenly moist. It should be neither too wet nor too dry. If your soil is very dry, water a day or two before seeding to soften it.

STEP 2. Use your lawn mower to scalp the existing grass to 1" - 1.5" and bag the clippings. This helps get the seed down into the soil.

STEP 3. If you have heavy clay soil or your ground is compacted from too much traffic, you may want to aerate and add gypsum. A core aerator pulls out plugs of soil and deposits them on the surface where they break down into a beneficial top dressing. Aerating every few years is good maintenance for cool-season lawns to alleviate natural traffic compaction. This practice allows better penetration of water, air and fertilizer. To further loosen heavy clay soils, add gypsum to your lawn after core aerating. 

If you don’t core aerate, you can still improve your soil before seeding by applying either Enviromax or Natural Guard Grass Clippings Decomposter. Enviromax is a liquid spray-on polymer which expands once it is watered into the soil, restoring pore spaces which allows water and fertilizer to get to the roots where they do the most good. Grass Clippings Decomposter (with 100% humates) creates a soil building process that results in more organic matter in the ground. This increases the nutrient uptake of plant roots. The fertilizer is absorbed better so you see more results.

STEP 4. Good seed-to-soil contact is crucial in attaining desired results. Small areas can be worked with a rake. For large areas, rent a vertislicer/seeder from Johnson’s Garden Centers. To avoid the “row” effect of new grass, overseed in one direction, then “cross-cut” at approximately 45 degrees from the first run. For this procedure, set the seed drop at 1/2 of the recommended application rate. 

For a healthy lawn, DO NOT EXCEED the recommended rate. Seed sown too thickly is a breeding ground for disease. A small amount of debris will be left behind after vertislicing. Don’t worry about raking it up unless there are very large clumps. A thin layer of debris will keep the soil moist while the seed is germinating and protect the new seedlings as they grow.

STEP 5. Apply ferti•lome New Lawn Starter (9-13-7) with a broadcast spreader at the recommended rate. (You may borrow a spreader from Johnson’s any time you purchase your lawn fertilizer at Johnson’s.) New Lawn Starter is high in phosphorus, which helps your grass seedlings get off to a good start. It is designed to help grass seed develop roots and mature stems before rapid growth begins.

STEP 6. Moisture is vital to grass seedlings. The seed bed should never dry out, but be kept constantly moist (not soggy). Water three to four times per day if necessary depending on weather conditions and soil type. Don’t water to the point that water is puddling or running off. Continue watering this way until the new grass reaches 1.5-2" then reduce the frequency of watering times but water for longer periods of time.

STEP 7. Start mowing your new lawn when some of the new grass reaches 3" tall. Don’t wait until all the grass reaches 3". The sooner you start mowing the faster the grass will start to thicken. Don’t mow more than 1/3 of the blade at any one time. Always make sure the blade is sharp. 

STEP 8. Apply ferti•lome Winterizer (25-3-6) 30 days following seeding and again 30 days later. These 2 applications will establish a healthy root system; build in winter hardiness; and give you early spring green up.

STEP 9. The cultivation necessary to plant grass sometimes brings weed seeds to the surface. To spot treat those weeds, spray with ferti•lome Weed-Out after the new grass has been mowed three times. Weed-Out may be used late into the season, but remember that in cooler weather Weed-Out takes longer to work.

STEP 10. Apply ferti•lome Crabgrass Preventer Plus Lawn Food with TEAM in late March/early April to feed your lawn while preventing crabgrass and other annual weeds from getting started in your turf. Or apply ferti•lome Crabgrass Preventer plus Lawn Food with BARRICADE in February for season-long crabgrass control while feeding your lawn.