As turf grass growth slows in late summer, weeds often become more noticeable. Even the most well-maintained lawns are seldom 100% weed free, and weeds that blended in to thick green grass a month ago stick out like sore thumbs in the short dry grass of late August. It’s not uncommon for crabgrass to pop now either, as the protection wears off from pre-emergent crabgrass treatments performed in spring.
There are chemical means of controlling most weeds, including post-emergent crabgrass, but heavy use of herbicides is not the long term solution.
“Weeds exploit poor quality turf,” according to the Virginia Cooperative Extension office. “The best weed control is a thick, healthy turf…”
To prevent weeds from outpacing grass in late summer, you have to build a truly healthy lawn, and there’s no better time to start than right now.
When the weather gets hot and rainfall is scarce, the temptation is to water every day in an effort to keep lawns green. The problem with that is, you’re also heavily watering weeds like nutsedge that grow much faster than turf grass. Some weeds have long taproots and can absorb more water than turf. Watering three or four times a week instead might not do as much for the short term appearance of the grass, but it’s much better for its long term health and will help avoid fueling weed growth.
Mowing less frequently and higher reduces stress on the lawn and keeps it greener. Also, if the grass is allowed to grow more and kept a little longer – four inches if possible – the weeds will start to become less noticeable.
As fall approaches, plan on aerating your lawn with a core aerator. Aeration relieves compaction and allows more water and nutrients to penetrate to the roots of the turf. If you choose to over-seed, the aeration also helps provide a seed bed. If part of the reason your lawn is in bad shape is poor soil conditions, applying compost to the lawn after aeration will help integrate organic matter and will build topsoil over time if performed repeatedly. The nutrients in the compost are a natural way to feed your lawn, but balanced, slow release fertilizer can help speed up the process.
Click the link for more information on lawn fertilization in Virginia from Virginia Tech.