The first step to overseeding is to assess the situation and to check for these problems:
• Poor drainage
• Deep shade
• Low fertility
• Improper pH
• Compacted soil
Failure to address these problems will reduce the chance of a successful renovation.
When a lawn is patchy and brown, you may be having trouble with air and water getting deep enough into the soil for it to be effective. Aerating your lawn, as well as overseeding it to promote grass growth, can turn a sickly lawn into a prize winner practically overnight.
Aerating is the process of removing small plugs of soil from your lawn to break up compacted soil and promote the proper drainage of water and the circulation of air throughout the soil. Compacted soil prevents roots from growing deep enough to withstand adverse weather conditions such as heat, drought and cold weather.
Aeration helps thatch, dead grass on the lawn, break down. This helps prevent thatch from choking off good grass in the lawn and keeps water from running off large areas, making puddles or creating drought-like conditions. Fertilizer, when applied to the lawn, is easily absorbed when the soil is properly aerated.
When to Aerate
Aeration should be done at least once a growing season, preferably in the spring or in the fall. March, April or May in the spring, or September, October or November in the fall are the best times to aerate. Aeration can be done with specially designed aeration hand tools, like a rake with plug making spikes at the bottom, or with motorized aeration machines.
Overseeding is the process of working new grass seed into an established lawn. This can be done over dead or patchy grass to promote new growth and improve the appearance of a lawn.
When to Overseed
Overseeding should be done only after the lawn has been properly aerated. Late summer or the early fall is the best time to overseed the lawn, to avoid the summer heat or drought that can kill the grass seed before it has had a chance to take hold. Weeds are less abundant during this time as well.
Watering your overseeding is important for the success of the new lawn. Water every day to about a one-inch depth. Once the seed has germinated you should water according to the recommendations for the type of grass.
1) Don’t lay seed before it rains. The water will wash it away.
2) Don’t apply pesticides before of after. Leave at least a month in between, maybe more.
3) Add compost, topsoil and starter fertilizer for an added kick.
4) Aeration is extremely beneficial for seeding.
5) There are pre-packaged mixes available that have seed, fertilizer, and mulch all in one bag.
Preparing your Lawn for Overseeding
First, check for proper growing conditions. Most hardware stores sell a soil test kit that measures pH and overall fertility. The test will tell you if lime or fertilizer is needed to increase the pH or nutrients. Also, if your lawn hasn’t been aerated in a while, chances are the soil is too compacted. Standing water is good indicator. Stick a screw driver into the ground when it’s dry to test. If you have trouble pushing the metal all the way down, the soil is probably too compacted. After checking for proper growing conditions, decide whether or not to aerate, fertilize, or lime.
Follow these tips to prepare for overseeding a lawn
• Mow the grass as short as your mower will cut. Almost scalp the grass (about 1 inch).
• Vigorously rake out grass clippings and thatch.
• Remove as many weeds as possible, either by digging or spot treatment of glyphosate herbicide
• Aerate the lawn area. Aeration will improve oxygenation, which will help the new grass seed grow faster and more robust.
• Top-dress the yard with a compost/topsoil blend. This will help incorporate organic matter into the lawn, improving soil structure, which will, in turn, improve grass germination and long term health.
How to Achieve Even Coverage of Seed
Once the yard is prepared for overseeding, use these techniques to achieve even coverage of the lawn with the grass seed.
• Calibrate your spreader-you do this to set the spreader drop rate according to your stride. How fast you walk will influence the coverage. Your spreader will have instructions for doing this.
• Then, fill the spreader with half of the seed and spread the seed evenly walking in one direction. Next, fill the spreader with the other half of the seed and overseed walking perpendicular to the previous direction. Whether you overlap each row slightly depends on whether you are using a drop spreader or a broadcast spreader. With drop spreaders, you do not overlap-but you do precisely line up with your row. Broadcast spreaders require overlapping the throw patter by about 1/3 on the next pass.
• To keep the seed coverage even, top-dress the grass seed with a light compost mix. You only want to just barely cover the seed. This is more of a dusting of material. It will help keep moisture near the seeds and help increase capillary action of the soil.
Follow-up Care after Overseeding a Lawn
Once you have successfully completed lawn overseeding, you need to care for it properly to ensure that it thrives. Here are the best ways to ensure good germination rates and healthy growth of your lawn overseeding project.
• After seeding, rake the area lightly.
• Protect the lawn from foot traffic from people and animals.
• Water the lawn gently several times a day. Let the seed just barely dry between waterings. Water the grass thoroughly to a depth of 4 to 6 inches. Then keep the seedbed moist. Water at least 1 inch of water a day. This will put water into the soil so that as the grass seed starts to germinate, it has the necessary moisture to do well.
• Once the grass seed has germinated well, switch the watering schedule to deeper and less frequent watering.
• Do not mow until the new grass reaches its normal mowing height. (About 3 inches for most grasses)
• Note: If you plan to overseed a large area, it is best to use a vertical mower and run it through the existing grass. The vertical mower will create a good seedbed.
Following the above steps will make overseeding a lawn an easy and successful project.