Weeds in a well manicured lawn will often stand out, especially if they take hold in small patches everywhere. Crab Grass can be especially annoying as it spreads quite quickly once it gets a firm hold. While there are a lot of chemicals around that will destroy Crab Grass, those chemicals are generally indiscriminate and will kill off every broad leaf grass in your lawn including clover, which is beneficial to a lawn.
The only way you can really prevent most weeds from taking hold is by making the area inhospitable to their needs. Weeds, especially Crab Grass, are just another form of grass – just an unwanted grass. As such, the Crab Grass seed needs a good environment in which to germinate, then grow into a full plant. That environment includes soil contact, sunlight, and water. Remove one or more of those components and Crab Grass will never get a start, let alone take over your lawn.
Of the three, water is the hardest to restrict. Your lawn needs water and there’s little you can do to stop nature providing it in the form of rain. That leaves soil contact and sunlight – and they are easy to control. A well maintained lawn should have a reasonable thatch covering. This on it’s own should prevent many of the weed seeds from finding the soil below. However, thatch alone will not stop every seed so there will still be some that make it through.
This leaves sunlight, and that’s easily controlled simply by changing your lawn mowing habits. The longer and thicker your lawn is, the more shade it will provide for the ground around its roots. This further helps your lawn as it slows down water loss caused by evaporation. If the soil is well shaded by your lawn, any weed seeds that do germinate will struggle to survive. Seedlings need sunshine to start the photosynthesis process; no sunshine, no food, no weed – end of weed problem.
If your lawn isn’t thick, then use a lawn repair tool to help over sow with fresh seed. As your lawn starts to thicken, let it get to around four inches in height before cutting, and when you do cut, leave it at around three inches. Whatever you do, don’t cut your lawn below two inches. That opens up the thatch to sunlight and the easy germination of weed seeds like Crab Grass.
