Grass seed grows and germinates best when daytime temperatures are around 50°F (10°C). Germination will not take place if overnight temperatures create heavy frost. Allow at least one to three weeks for the seeds to germinate. You will then want to allow the grass seed a few weeks to get rooted before a frost.
Normally, thatch is beneficial until it becomes thicker than 1 inch (2. 5 cm). [4] X Expert Source Jeremy YamaguchiLawn Care Specialist Expert Interview. 21 January 2020. Go over the top of your soil lightly with a thatch rake. This process is called “dethatching. " If you can’t find a thatch rake, you can use a leaf rake, although you may have to rake a little harder in order to remove the thatch. You may be able to rent a gas-powered dethatching machine from your local hardware rental center. This will save you a lot of time and hard labor.
Although roto-tilling is common practice when seeding a new lawn, it is also helpful for overseeding. The only difference between roto-tilling before overseeding and before planting a new lawn is the depth: overseeding requires only tilling about 1 or 2 inches into the soil, while new lawns require 4 to 6 inches. Aerate the soil using a broadfork, being careful not to break the underlying structure of the soil too much. [5] X Expert Source Keith SouzaHome Improvement Specialist Expert Interview. 20 August 2021. Breaking the soil open hurts the root structure of the existing grass and gives new weeds a chance to invade. If you have a large area to aerate, consider renting a gas-powered aerator.
You can buy a kit and perform the test yourself, according to direction on the labeling. You can hire a professional or ask your local city to perform a pH test for you. While this step is not essential to overseeding, it can mean the difference between a successful project or a waste of your time and hard work. You can risk skipping this step, but it is usually worth it in the long-run.
Lay a very thin layer of compost over the entire surface of the lawn. Too little is better than too much. Too much compost and your existing grass will effectively be buried under compost and die. Spread the compost out evenly over the entire surface of the lawn with a rake, preferably a thatch rake. Make sure that compost does not remain on the top of the grass. Remember to rake lightly when spreading the compost with your rake.
Make sure you choose a variety of seed that blends nicely with your existing lawn. Bermuda grass might be great, but it probably doesn’t blend all that nicely with Fine Fescues. It’s best to stay away from cheaper brands of seed. You really get what you pay for. If you decide to economize too much, your lawn may carry the telltale sign.
Put a light layer of topdressing over the seeds. Use the back of a leaf rake and lightly rake or tamp the topdressing.
In the beginning, it helps for the seeds to be moist or damp almost around the clock. This will help them germinate. After they have germinated, too much water can eventually kill the seedlings.
Do not overuse the nitrogen fertilizer. Too much nitrogen can burn the new germination and seedlings.
