Overseeding 101: Why, When and How to Overseed Your Lawn

Overseeding is an important part of lawn care. It basically means spreading grass seed over your existing lawn. And, although important, it’s a step that homeowners often neglect.

But who can blame them? Between mowing, watering, and fertilizing, we’re already spending so much time on our lawns. We deserve a break. We deserve to take it easy on the patio. But here’s the thing: if we don’t overseed our lawns, we’ll have problems that’ll cost us even more time (and money) to fix.

Why Overseed?

  • Get Thick, Weed-Free Lawn. One of the reasons you want to overseed your lawn is to fill in thinned out areas. As your grass plants mature, their reproduction rates slow down, and you’ll start getting bare patches that open up your lawn to weeds. So you want to overseed as necessary to give weeds absolutely no room to grow, as well as bring back a lush, green lawn.
  • Rejuvenate Your Lawn. If you have an older lawn, you can improve its resistance to drought, disease, and pest by overseeding with newer, hardier varieties of grass. It’s not unlike injecting new blood into a sports team with new signings to improve the overall condition of the team. You spend less on maintenance with newer, hardier grass, as you would on rookie contracts. While mature grass and players tend to cost more for less!
  • Winter Green. For those who live in the south where warm-season grasses grow, overseeding allows you to plant a cool-season variety to keep your lawn green throughout the winter. This is called winter overseeding. The key is to have the cool-season grass die out come spring, and not let it interfere with your warm-season grass when it comes out of dormancy. Tall fescue, annual ryegrass, and perennial ryegrass are commonly used for winter overseeding.

How Should You Overseed?

Step 1: Aerate

Overseeding is a simple three-step process. First, you need to open up the soil. This is done by aerating your lawn, which involves removing plugs of soil from the ground. This is an important step because it will allow grass seeds to make contact with the ground and properly germinate, and those holes in the ground will allow water, air, and fertilizer to get through.

You can hire someone to aerate your lawn or rent a power aerator from your local home improvement store. If you choose to do it yourself, go over your whole lawn three times with the aerator in different directions to ensure proper aeration. You can also purchase an inexpensive manual aerator to do the job. But this tool will require more time and elbow grease!

Yard Butler Lawn Aerator
This manual aerator is also a handy tool to have. You can aerate your lawn at anytime without the need for heavy machinery.

Once you’re done, leave the plugs – with all their yummy nutrients – on the ground. They will work their way back into the soil.

Step 2: Seed

The next step would be to throw down some compost, organic fertilizer, and grass seed.

Spread about half an inch of compost over your lawn and rake evenly. Then use a broadcast spreader to scatter your fertilizer and grass seeds. It doesn’t matter whether you fertilize or overseed first, but rake everything in to ensure proper growth.

Scotts Turf Builder Broadcast Spreader
If you don't already have one, get a broadcast spreader to scatter fertilizer and grass seeds on your lawn.

You may have heard of using “starter fertilizers” for overseeding. These products have a high proportion of phosphorus intended to promote root growth in new grass. But if you’ve been taking care of your lawn organically, these synthetic products mean nothing to you, as your soil should have plenty of phosphorus alongside other vital nutrients to grow healthy grass. We wouldn’t recommend using “starter fertilizers” because you usually end up putting more phosphorus than needed, causing water pollution.

Step 3: Water

The third and final step, which can make or break your efforts, is to water your lawn properly. Grass seeds need to stay moist so that they can germinate. That means you have to water light and often for the first few weeks, rather than deeply and infrequently as you would with an established lawn.

You should be watering two or three times a day for the first two to four weeks. But be careful not to drown your lawn in water. It only needs to stay moist. If it rains, simply cut back on watering.

When’s the Best Time to Overseed?

Timing is important. Cool-season grasses grow in the spring and fall, which means – surprise, surprise – those are the best times to overseed. But we would argue that fall is the better of the two seasons.

If you overseed in spring, your grass has to compete against weeds. And guess what? Those aggressive weeds will win. But in the fall, there are fewer weeds to compete against. So overseed in the fall, before it gets too cold. September is the best month to overseed.

On the other hand, warm-season grasses grow in the summer, so the best time to overseed is late spring or early summer. The best months to overseed are May or June.

Other FAQs

To finish off, we want to address some commonly asked questions about overseeding a lawn.

  • Should you overseed every year? No, this isn’t necessary, unless you are winter overseeding. Overseeding to restore a lawn only needs to be done every few years, and depends on a number of factors like wear and how well you maintain a lawn. On that note, aeration likewise is only required every few years, unless your soil is heavily compacted or you need to overseed. That’s why people don’t buy power aerators. They’re heavy, bulky, expensive, and not worth having for only a few uses.
  • What’s the best grass seed to overseed with? As we mentioned earlier, the best varieties of grass for winter overseeding southern lawns are tall fescue, annual ryegrass, and perennial ryegrass. For restoration purposes, the grass seed you choose depends on where you live. For instance, in the cool-season grass zone, most people overseed with a mix of cool-season grasses: Kentucky bluegrass, perennial ryegrass, and tall or red fescue. Your local nursery should carry grass seeds suitable for your climate. New varieties and mixes come out often, so it’s a good idea to ask your nursery for some up-to-the-minute advice.
  • Can you use too much grass seed? No, unless you really overdo it and create unnecessary competition among the grass. Some seeds will simply not germinate at all, or get blown away, while the stronger seeds survive. But there’s the issue of wasting money by using too much seed. So follow the instructions on the label as closely as possible.
  • Why won’t my grass seed germinate? It’s usually due to one of these things: you chose the wrong time overseed with the conditions being too hot or too cold, you haven’t watered properly, your grass seeds have gone bad, or your soil is in poor condition with not enough nutrients to feed the grass.

You’re an Overseeding Pro!

We don’t have to tell you how disappointing it is to have a thin, weed-infested lawn. But now that you learned everything there is to know about overseeding, you can stop that from happening.

We guarantee that if you include overseeding as part of your lawn maintenance program alongside watering, mowing, and organic fertilizing, the grass will be greener (and thicker) on your side!

Have Fun Out There!