Overseeding Your Lawn
The key thing with overseeding yards is to have seed-to-soil contact. If we just sprinkle some grass seed into this yard, some will grow, but it won’t be quite as effective as if we can get that seed worked into the soil and get it actually touching the soil surface.
We can get that seed-to-soil contact in a number of ways. Sometimes we can use a core aerifier, which will poke holes in the ground. We can poke holes in the ground and then sprinkle our seed in over the top of that. The seeds will fall in those holes, and give us some seed-to-soil contact. That works very effective, and we should core aerate our yards to alleviate compaction and get air and water movement into the soil. The downside is that the core aerification holes are usually a couple inches apart, and you’ll end up with just grass growing in those core aerification holes.
A better way of overseeding your yard, is to use a power rake or a verticutter. A power rake or verticutter cuts grooves in the yard. We can cut a series of grooves cutting in one direction, sprinkle our seed across, and then come back with the verticutter and cut a second set of grooves in a ninety degree direction. That works the seed into all those grooves, and gives us a very good seed to soil contact.
If this was my yard, this is what I’d be doing. First, come in with your mower and mow this grass pretty short. Not so short that you’re scalping it and causing damage to the ground and to the mower – but mow it an inch and a half, or two inches. Mow it short, and remove that leaf debris that’s on top of the yard. Take that aside and put it in your compost pile, or dispose of it properly.
Once you’ve got the grass mowed short, what I would do then, is to come in and core aerate the yard. This pokes holes in the ground. Let those cores dry out for half an hour to four or five hours – usually an afternoon.
Then, come back that afternoon, and run the verticutter across the yard. Once we’ve got those grooves – there may be more debris. Take a leaf rake and rake up all that debris up and put it in the compost, or dispose of it properly.
Next, sprinkle your seed out across the yard, nice and uniform with either a drop spreader or rotary spreader. And then take the verticutter and go in a second direction (90 degrees) to the first one, and run another set of grooves across the yard.
Once that’s done, sprinkle out some starter fertilizer across the yard, nice and uniformly, according to the rate table, and then turn on the irrigation and keep it moist. The key thing with keeping it moist is that we want to keep it light and frequent. And we probably want to be irrigating in the middle of the day or afternoon, when the sun is at it’s hottest, to keep that soil surface moist.
Once the grass grows and begins to mature and starts getting to it’s height that it’s supposed to be (three inches for tall fescue or two and a half inches for Kentucky bluegrass), we want to get out there and start mowing that grass. Frequently I’ll see people let that grass grow real tall thinking they want to help that grass get a good head start. But what they’re doing is letting that one individual plant grow real tall all by itself and shade out some of it’s brothers and sisters beside it. We want to cut it when it gets to it’s right height, so that it will start tillering or sending out rhizomes that are in the ground and spreading out across the surface. Also, not all of its energy is going into just upright growth.
This feature story prepared with Rodney St.John, Kansas State University Research and Extension, Turfgrass. For more information, visit your local county extension office or visit our website at KansasGreenYards.org.