Popping up throughout your lawn during the growing season, crabgrass is a stubborn and determined grassy weed. It can thrive in the hot summer heat as long as it has access to moisture and nitrogen, which your yard probably has plenty of.
Preventing this pesky weed before it sprouts is the best way of ensuring your yard stays crabgrass-free, so it’s a good idea to not only know what prevents it but also when the weed germinates so that you can stay ahead of it.
Although the answer largely varies based on the average soil temperature, this article will go over everything you need to know to stop crabgrass from taking over your lawn.
When Does Crabgrass Germinate?
One of the most significant indicators of when crabgrass will germinate is the soil’s temperature, not necessarily the time of year. Since this is the case, it’s important to pay attention to the changing weather so that you can adequately prevent the germination of the crabgrass.
Keep an eye on what the temperature is supposed to be like as the weather begins to warm up coming out of winter, as this time will be crucial to stopping the growth of the unwanted weed.
When the average daily soil temperature reaches between 14 to 19 degrees Celsius—or 57 or 64 degrees Fahrenheit—crabgrass will begin to germinate. Once the daily soil temperature reaches an average of 22 degrees Celsius—or 73 degrees Fahrenheit—all of the crabgrass will most likely be germinated.
Since the soil temperature can differ from the air temperature, many people like to use a soil thermometer so that they know exactly what’s going on with their yard; however, this isn’t necessary.
Different areas of your yard will have different soil temperatures, though, so keep this in mind when taking a rough guess. The areas that are in the sun will reach the crabgrass germination stage sooner than the areas that are in the shade, so that’s a good thing to keep in mind if parts of your yard are either particularly sunny or shady. Also, grass next to concrete or sidewalks will germinate sooner since concrete conducts heat, so you may want to take this into account as well.
Does Crabgrass Germinate in the Fall?
Crabgrass begins to germinate as the temperatures warm up, not as they cool down, so you won’t likely see the weed starting to grow as winter approaches. Crabgrass is an annual plant, meaning that when it dies, it doesn’t come back the following year.
Unfortunately, this doesn’t mean that after one season, your troubles with crabgrass are done for good. Before crabgrass dies during the fall, it drops its seeds, which will lay dormant until the weather begins to warm up come springtime.
Each crabgrass plant can produce a whopping amount of up to 150,000 seeds, which have the ability to remain viable for many years even if they don’t germinate at the first chance they get.
This weed is incredibly determined, although don’t worry—there are ways to banish it from your yard for good. Remember that it’s always best to stop the growth of crabgrass before it even starts, taking action right before the seeds germinate in the spring. Once they get started, it’ll be much harder to take control and stop the spread and the growth of the weed.
What Month Do You Put Down Crabgrass Preventer?
Just like crabgrass germination, the exact time to put down the crabgrass preventer is better determined by the temperature, not the month. Pre-emergent herbicides will be your partner in crime when it comes to getting rid of crabgrass, killing the seeds before they begin to sprout. They work by inhibiting root development and, therefore, seed germination–stopping the crabgrass from becoming an established plant.
You’ll want to time spreading your pre-emergent herbicide with the weather, the best time to apply it being right before germination. Since the weather can be somewhat challenging to predict, wait until the temperature starts creeping up closer to 14 degrees Celsius—or 57 degrees Fahrenheit—before applying pre-emergent.
It’s better to apply it slightly too early than it is to apply it too late, so keep that in mind as well. Depending on what the climate’s like where you live, crabgrass can start germinating anytime from early to late spring, so you’ll want to have your pre-emergent applied by early spring in almost any case.
If crabgrass has already started to sprout in your yard, you may be wondering about what to do next. While the window for using the easiest and most effective option for getting rid of crabgrass has unfortunately already passed, there are still some things you can do to eliminate or at least reduce the amount of crabgrass growing throughout your lawn. You’ll want to enlist the help of a post-emergent herbicide, which is designed to target actively growing plants rather than seeds.
This can start to become tricky, as it can be difficult to get rid of crabgrass without harming the rest of your lawn that you put lots of effort into. Although we view it as a weed, crabgrass is still a type of grass, so most common selective weed killers won’t harm it, while non-selective ones will harm your wanted grass as well. There are limited options of non-selective herbicides out there that will kill off crabgrass while still leaving your lawn healthy, but thankfully there are still options.
Crabgrass is a pesky plant that can be hard to get rid of, although with the proper tools—and more importantly, adequate timing—it’s possible to eradicate it from your lawn. Killing the seeds before they germinate is key, which you’ll want to do in early spring, right before temperatures start warming up.
Using a pre-emergent herbicide is by far the easiest and most effective way of getting rid of crabgrass, so it’s plenty worth it to plan ahead for this coming spring to ensure your yard stays crabgrass-free.