Have you nursed your lawn or flowers all summer, only to find them riddled with brown patches after autumn's first frost? In all likelihood, those unsightly spots aren't dead areas, they are crabgrass. Here's how to prevent and kill crabgrass while giving your lawn and garden the healthiest environment you can.
Crabgrass is actually an annual grass weed and is a universal problem to homeowners in the United States. Crabgrass pops up in spring and develops into large, flat, thick clumps that spread widely. It smothers grass and plants. Crabgrass is found in either in smooth or large varieties with seedheads that differ in width. Crabgrass loves hot, dry weather and is typically about 2-5 inches long.
Because it is an annual, crabgrass dies after autumn's first killing frost. It leaves behind dead patches; if untreated, those bare spots will fill with crabgrass the next spring as dormant crabgrass seeds sprout.
How to control crabgrass: maintain a lush, thick lawn and well-mulched, well-tended fruit and vegetable beds. Healthy landscapes (lawns that are dethatched regularly and mowed to a not-too-short height, or flower beds that are watered well and mulched) are less likely to be stressed and more likely to overcome any weed invaders like crabgrass. Avoid overwatering, which can stress plants.
To get rid of crabgrass naturally, or without chemicals, try mulching. Mulch acts as a suffocating blanket by preventing light from reaching weed seeds. At the same time, mulch holds moisture for your plants and provides nutrients for your soil as it decomposes. Apply coarse mulch, such as bark or wood chips, directly onto soil. Leaves, grass clippings, or straw work better as weed deterrents with a separating layer of newspaper, cardboard, or fabric between them and the soil. Look for organic mulch as an organic crabgrass control method.
In the spring, two weeks before your last expected frost, apply a preemergent weed killer with corn gluten meal. This will kill the crabgrass seed before it has a chance to take root. However, do not use any preemergent products when you are planting other seeds; they will prevent all seeds from germinating.
Crabgrass also can be killed with a product labeled as a crabgrass killer, which should contain acetic acid; be sure to follow all label and safety precautions for this crabgrass spray. If you find crabgrass in vegetable or fruit gardens, pull the offending weed and throw it away, but do not toss it in the compost pile where its seeds can spread. Use weed pullers or a trowel as a crabgrass removal tool to make sure you get the roots up.
Apply a preemergence herbicide (crabgrass preventer) with fertilizer in it to kill crabgrass while supplementing your lawn. While these products take out a step in lawn care, it's important to look at the release speed of the fertilizer. Look for slow-release fertilizer if you are applying preemergence herbicide in the early spring—quick release fertilizers with crabgrass killer are typically fine to use for summer and fall crabgrass control.
The best indicator for applying crabgrass preventer during the season? Forsythia. This popular landscape shrub is grown for its striking yellow flowers in early spring, when most trees and shrubs are still bare. When the blossoms start to drop to the ground, it's time to put down the crabgrass preventer.