Overseeding refers to the act of adding turf grass seeds on an existing turf lawn. It can give very good results, granted that you follow a few simple rules. You will find on this page a few overseeding rules of thumb.
The Right Seeds for Your Conditions
Two of the most important factors if you want your overseeding efforts to be successful are sun and water. Climate is also an important factor, but chances are that all the nurseries and hardware stores in your location sell seeds that are well adapted to your climate. But if you live in Hawaii and order grass seeds form a nursery located in Alberta, Canada, then you might just receive cool season grass seeds, while what you need is warm season grass seeds.
So how do you choose grass seeds that are well adapted to your conditions? Well, the first thing to know is that grass seeds are usually sold as mixes, so in a single bag, you may very well get five different seed varieties. You should read what’s written on the bag and look for the names of those varieties you know are well adapted to your conditions.
- If you have lots of sun, choose sun loving grass varieties, such as Kentucky bluegrass (a cool season grass, it is well adapted to regions with harsh winters) or bermudagrass (a warm season grass, it thrives in regions with harsh, long summers).
- If you have less than two to four hours of direct sunlight per day, choose seeds adapted to shaded areas (full shade to partial shade varieties), such as red fescue (cool season grass) or Zoysiagrass (warm season grass).
- If you have no direct sunlight, you should know there is simply no grass variety that thrives in complete shade, so your lawn may survive in such conditions, but it will never be beautiful, no matter how much fertilizer and weed control products you use. So why not consider a radical grass replacement project.
- If you have ample rain water, then most turf grass seeds are good for you.
- If water is scarce and if you are likely to suffer droughts, then choose drought resistant varieties, such as Zoysiagrass (warm season grass). Once your lawn is well established, keep it as long as possible. The longer the grass, the longer its roots. Longer roots are more likely to keep moisture in the ground, to find what little water there is and to survive droughts.
You may very well consider using different varieties for different parts of your yard. You may, for instance, choose one mix for your sunny front yard, and another one for your backyard, if it is less sunny.
A word about those seeds covered in special chemicals supposed to give them a boost or to make them germinate with less water. While it may be true that they can have an edge over comparable untreated seeds, what is absolutely certain to make your overseeding efforts successful is to buy top quality seeds and to do things right, as explained on this page.
For more information on selecting turf grass varieties, you may see the following:
- The University of California Agriculture and Natural Resources Department’s UC Guide to Healthy Lawns page.
- The Ontario Ministry of Agriculture and Food’s Lawn Establishment page.
- Virginia State University’s Selecting Turfgrass page.
The soil is also very important. If it is too poor, your seedlings will not get enough nourishment. If it is too hard, their roots will not be able to penetrate the soil. If it is too dry, they will dry out, yet if it is permanently wet, they will rot. So before you start overseeding, check your soil to ensure it will not ruin your efforts.
If your soil is too poor, consider using mild, natural fertilizers, such as compost or simply black earth before overseeding. Do not use anything too strong, as it will damage the seedlings. And stay away from corn gluten, as it will prevent germination altogether.
If your soil is too hard, use a lawn aerator. Aerating your soil will let water and air penetrate it, which will make your soil richer and more alive. This, in turn, will make your soil less compact. Note that this will happen happen over weeks and months. Adding natural fertilizers will help and speed up the process.
Whatever it says on the bag of seeds you bought, once you are done overseeding your lawn, you will have to make sure your seeds don’t dry out during the first few days and weeks. So, if nature doesn’t provide the water, you will need to.
If, on the other hand, too much water is the problem, then there are two possibilities. If the situation is exceptional, wait until the weather becomes more clement. If you lawn is almost always damp or soggy, then overseeding in these conditions is useless. You have to fix your lawn drainage problem.
What is the Best Time for Overseeding?
The best time is when the conditions are mildest.
- If you live in a colder region where there are harsh winters, the best times are towards the beginning or the end of the summer. Seedlings will not fare well with frost, but they won’t fare well with sultry weather and harsh sun rays either.
- If you live in a region where the weather is hot to chilly all year round, choose any period when the weather conditions are the least harsh.
Once you know you have the right seeds and the right conditions, you are ready to start overseeding. Overseeding is quite simple in fact. It can be done by hand, but it’s much simpler if you use a spreader. Different types of turf grass grow differently and take up more or less space, so follow the instructions on the bag of seeds to know how much to use. Using too much will not necessarily give better results.
Mowing your Lawn
The seeds need to be in contact with the soil for them to germinate and take root, and for that to happen as much as possible when overseeding, you should mow your lawn the shortest you can (you should not go below one inch or two and a half centimeters). The best thing is to do this gradually. Mow it shorter than usual one day. Wait a few days and then mow it even shorter. For tips on how to care for your lawn, see our lawn care page. And if you usually mulch your grass and leave the clippings on the ground, don’t do it then, because it may shield the seeds from the soil. And bear in mind that this must be done when the weather is least likely to be harsh.
While it may be a good idea to feed your seeds, it must be done very gently. A good idea is simply to sprinkle black earth over your lawn after overseeding. Most black earth mixes contain small quantities of natural fertilizers, such as manure or compost. This will give your seeds a boost without burning them.
It may be a good idea to do a very light raking to ensure the seeds go all the way down to the soil. Just make sure that you don’t move the seeds around and end up with spots where there are too many and spots where there are almost none.
Nothing will happen to the seeds until there is enough water to wake them up. So to start the process, if there is no rain in sight, you should water your lawn thoroughly.