Key Points
- Crabgrass’ ability to spread makes it hard to control. Its ability to spread is due to the number of seeds it produces and its tolerance of challenging conditions.
- The best way to control it is through prevention. This includes the use of a natural pre-emergent at the right time.
- Prevention extends to proper lawn care throughout the summer. Keep your grass as vigorous as possible so it can compete against crabgrass.
What Is Crabgrass and Why Does it Spread So Easily?
Crabgrass is an annual weed that is multi-stemmed and often grows low to the ground. A warm-season grass, it thrives in hot weather, making it one of the fast-growing weeds of the summer season.
One reason it spreads so easily is that it’s tolerant of conditions that cool-season lawn grasses aren’t tolerant of. Another reason is that crabgrass is a prolific seed producer. One crabgrass plant can bear 150,000 seeds (which can lurk in the soil for years before germinating).
A crabgrass plant can grow surprisingly large, which helps account for this prodigious seed production. As the stems creep along the ground, roots form at the nodes. This allows it to take up more nutrients and water, which sustains a plant of ever-increasing size.
Since wild birds eat the seed, they help spread it. So if a neighbor down the street has crabgrass in the lawn, there is a good chance that you, too, will have to fight the weed.
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Natural Ways to Stop Crabgrass Before it Starts
The best way to control crabgrass is to stop it before it even begins to grow big and flower. Target its seed germination, and you can get the upper hand against crabgrass. There are two natural methods for achieving this:
- Apply corn gluten: Corn gluten is a natural product that has herbicidal properties.Using a soil thermometer, start taking readings of the soil temperature in early spring. You are waiting for the time when the soil temperature reaches 55°F to 60°F (which is when crabgrass seed starts to germinate). If it maintains this temperature for a few days consecutively, then it is time to apply the corn gluten.
- Mow grass high to reduce crabgrass germination: Keep your lawn mowed at a height of at least 3 inches. This casts enough shade to reduce crabgrass seed germination.
What to Do if Crabgrass Has Already Sprouted
When you take preventive measures to stop crabgrass, you have a decent chance of succeeding. But once crabgrass germinates, it has the upper hand. This is especially true if you believe in staying organic and do not want to use a chemical herbicide to kill crabgrass. There are still a few steps you can take, but they are mainly measures geared to improving your chances of controlling crabgrass for the following year:
- Physically remove the crabgrass plants: One option is to remove the crabgrass plants while they are still young. However, because removal is labor-intensive, this method is feasible for only a small area or for a very minor infestation. You can pull the plants by hand, but using a small tool such as a garden trowel is better, because it allows you to get more of the roots.
- Maintain lawn health: Crabgrass is tougher than your lawn grass in summer, especially if you grow a cool-season grass. Crabgrass thrives in the hot, dry conditions that a cool-season grass dislikes. It is also more tolerant of compacted soils and soils low in fertility than lawn grasses are. Your job, then, is to give your lawn grass every artificial advantage possible to help it compete. This means watering and fertilizing your grass on the proper schedule, as well as ensuring that the soil is properly aerated.
- Fill in bare patches: If you do not maintain lawn health during the summer, thin or bare patches may begin to form in the lawn. Crabgrass will exploit these patches quickly. At the earliest feasible time, sow grass seed over these patches to fill them in again.
FAQ
Crabgrass seed germinates when the soil temperature reaches 55 to 60 degrees Fahrenheit.
Horticultural vinegar will kill crabgrass roots.
You can make quick progress in controlling crabgrass even in a yard heavily infested with it, simply because it’s an annual. However, if there’s crabgrass in your neighborhood, crabgrass control will be an ongoing project.