What is crabgrass?

Crabgrass is an annual grassy weed with broad blades that have a rough texture and are a lighter green than turf grasses. Since it is annual, it germinates in the spring and develops during the summer leaving lots of fresh seeds. Then once late fall arrives crabgrass dies off. The plants that are there this summer will not return. However, their seeds will be left behind to germinate during the following season.


What does crabgrass look like and how did it get into my lawn?

Crabgrass is a low-growing weed with lots of stems that form flat clumps. The blades are coarse, pointed and short. Crabgrass is also a much lighter green than the rest of your grass. Crabgrass can spread by several methods.  Most often bird droppings containing seed land in your yard as they fly over. From a single seed or two, you can end up with thousands of plants in a season. Crabgrass prefers full sun, however it is highly adaptable and will even grow in poor, dry or compacted soil.


How does crabgrass prevention work?

Crabgrass, unlike most lawn weeds, grows from seed that the mother plant produced the previous summer. The mother plant dies completely over the winter never to be seen again. In early spring (starting about now) the seeds germinate and start to grow. Crabgrass preventer is an agent that dissolves and forms a coating on the surface of the soil. ANY seeds that try to sprout and push a root through that barrier are killed. If crabgrass preventer is applied long before the crabgrass seeds are germinating, that thin barrier breaks down and won’t be effective when the crabgrass seeds finally sprout. In fact, crabgrass preventer can still kill the seedlings up to the point that they’ve formed three blades. In other words, better to apply a bit late than WAY too early. Any time in the next 2 weeks looks like it would be perfect timing. You don’t get to decide when the right time is to apply crabgrass preventer…the season does.

When should I apply a crabgrass preventer?

          The tricky part is knowing when to treat your lawn. When soil temperatures reach 55-60 degrees Fahrenheit, crabgrass seed will germinate. Since not many of us have a thermometer stuck in the ground 24/7, there’s a better way of gauging the right time. Many people rely on the tried and true method of the forsythia bush…it blooms a few weeks prior to the germination of crabgrass. Because we want to kill the crabgrass before the seedlings emerge, lawns must be treated when the forsythia blooms. However, if crabgrass preventer goes on too early you will not get control later in the season. Another good rule of thumb is that we need 3 consistent days of temperatures reaching 55 degrees Fahrenheit. All crabgrass preventatives will kill infant crabgrass. If your lawn has developed a crabgrass problem, mature crabgrass must controlled by a liquid.


As always, your helpful and knowledgeable staff at Gemmen’s Home & Hardware are happy to assist with any questions you have for crabgrass prevention or any other lawn care needs. You can stop in the store with any question large or small or simply give us a call at 616-669-1118.