In March, it’s still too early to do much with warm season grasses like Bermuda, Zoysia, Centipede, and St. Augustine. However, if you have a cool season grass, like Fescue or Kentucky bluegrass, now is the second best time to overseed. Here are my suggested steps for getting your cool season lawn in top shape.
Assuming at least 50% of your lawn is still grass and not weeds, then proceed with my plan. Otherwise, you might want to consider starting over from scratch. First, get a soil analysis done through your county extension service. You’ll learn all you need to know about what nutrients you’ll need to provide to give your lawn the best chance of performing. Be sure to follow the application rates listed on your analysis. Do this right away. You need time to add the amendments before you do some of the following suggestions for best results.
On the day you are ready to spread the seed, first mow the grass a bit on the low side. Next rake or blow any leaf or grass debris from your turf area. You want to start with as clean a slate as possible. Then, aerate your lawn with a core aerator. The term core refers to the plugs of soil that are removed from your lawn as the machine does the work. Although the cores may be unsightly, don’t worry. They’ll wash back into the soil quickly. In the mean time, the voids left by the cores allow oxygen deeper into the root zone, and generally creates a more favorable environment for grass roots to grow by relieving compaction. The voids will also be filled in with new organic matter, as well as lime or fertilizers that you might be adding.
Based on the results of your soil analysis, you may need to add supplemental nutrients or adjust the soil pH. Add those ingredients now, while the voids are still open. This gives s the best chance of the amendments making their way quickly below the surface where they can be most effective.
Next, add grass seed. Distribute the seed in a back and forth pattern. Once complete, go over the same area again but this time, cross the original pattern at a 90-degree angle. Think of a checkerboard pattern. This ensures the best coverage. Resist the temptation to cover the lawn area with so much seed that it looks like a new carpet. Cool season grasses do best when you apply at a rate of no more than five pounds per 1000 square feet. This is much less than you intuitively are inclined to do. Trust me on this. If you add too much seed now, you will have a beautiful stand of grass until summer. As soon as the heat and drought kick in, a heavily seeded lawn will suffer from water needs, disease, and decline. In just a matter of months, your lawn problems will be back.
Once the seed is down, use a water-filled roller to go over the entire lawn area. This ensures the best seed to soil contact; a very important point for good germination.
For cool season grass to germinate quickly, it must stay constantly moist. Until the seed germinates, irrigate your lawn several times a day for very short intervals. You are only attempting to keep the seed moist, not water your lawn. Four very brief sessions of only a few minutes should be adequate. You may even want to apply a light layer of straw mulch to assist in retaining moisture. Once you have good overall germination, you can back off on the watering. Ultimately, an inch of water per week is your goal. Ease into getting to that goal.
Finally, mow your lawn once the grass roots have become well established and the blades are tall. A lawnmower can do a lot of damage to newly sprouted grass. I usually wait about two to three weeks before making the first cut. Although cool season grasses can suffer and decline in the heat of summer, following the above guidelines will give your lawn the best chance of not only surviving, but looking good.