What Does “Overseeding” Mean?
Is your lawn composed of cool season grasses? If so, it may well take a beating from the heat to which it is subjected in summer. After all, by definition, cool-season grasses crave the cooler temperatures of spring and autumn. But there’s something you can do to undo summer’s assault. It’s called “overseeding lawns” “Overseeding lawns” is just what it sounds like. Namely, you’re sowing seed over existing grass, in order to fill in the bare patches. Therefore, overseeding lawns makes sense only if the existing grass is healthy enough and abundant enough to be worth keeping. If you currently have only 50% coverage, then you need to tear up the old lawn and start a new lawn from seed.
Preparations for Overseeding Lawns
Another step to take to promote contact between seeds and soil is core aeration, or “lawn aeration.” This step will help reduce lawn thatch, which stands in the way between grass seeds and the soil they’d like to call home. In severe cases, you may need to add a layer of topsoil before overseeding lawns. For instance, due to shallow tree roots popping up on the lawn, your topsoil layer may be too thin. Spread 1/4″ of screened topsoil over such an area, and rake it in.
The recommended rate for overseeding lawns is 4-5 pounds for every 1000 square feet that you need to cover. For the proper operation of overseeding lawns, use a spreader. Set the spreader to the recommended overseeding rate. At the same time, apply a starter fertilizer for better results. The grass seeds must be watered properly, in order to germinate. Use just a fine spray, as you don’t want to create a flood! The soil should be kept evenly moist, which may mean several waterings per day (depending on the weather), for several weeks. After the grass blades sprout, you’ll still need to water a couple of times per day. If you know your schedule won’t permit this, the time to look into automatic irrigation system is before overseeding lawns, not after.
The best time for overseeding lawns that have cool-season grasses is in September; the second-best time for overseeding lawns is in March or April.