When Does Crabgrass Germinate?

Crabgrass is a topic so uncouth and unattractive that a general search for it only yields ways to fight it and a Z-grade horror movie from 1958 entitled “Attack of the Killer Crabgrass.”

We didn’t watch the latter, but we can certainly speak on the former.

We’re just a few short months away from the beginning of Spring, the greenest time of the year. Gardening enthusiasts are chomping at the bit to start the season after nearly a full year of restricting their time outdoors. Truly, it will be a Spring, followed by a Summer, to remember.

But though Spring is a reason to get excited, the gardening community still has to deal with crabgrass’s annoyance and hazards. So when do you know just when to prepare your lawn to fight off this killer weed?

It can be hard to tell, as the specific time of year crabgrass starts to germinate varies annually. But one should expect crabgrass to germinate during the same season you want your lawn looking its best.

What is Crabgrass?

You’ve probably seen patches of crabgrass in thin lawns during the growing season around your neighborhood but never knew quite where it came from. Crabgrass is weed that shows up in the bare spots of grass.

It grows, lives, and dies all within a year, only to repeat the cycle. It can be sometimes difficult to identify as it adapts to its environment, often cloaking itself near the grass you want to keep.

Once crabgrass seeds begin germination and start to grow, you won’t remove the seeds, which will start to grow the following year again. Every crabgrass plant produces 150,000 seeds.

If not taken care of, it can overrun your yard, expelling the grass you work hard to keep looking fine.

But When Exactly Does Crabgrass Germinate?

A good rule of green thumb is to pay attention to your soil temperatures. Crabgrass begins to germinate when average soil temperatures daily reach between 57 and 64 degrees Fahrenheit.

When it reaches a standard of 76 degrees, all the crabgrass in your yard will have germinated. However, soil temperatures will differ in different parts of your yard. If a portion of your yard is covered in shade or a covering, for instance, the soil temperature will take longer to rise.

Nearby sidewalks or concrete conducts more heat in the soil, which means crabgrass is likely to grow faster there.

The weather is also a great predictor of when crabgrass will germinate. The daily air temperature is much easier to keep track of than soil temperature, and you can use the Growing Degree Day model for germination predictions.

Preventing Crabgrass Before It Starts

The ideal way to deal with crabgrass is to use a preventer with pre-emergent herbicides. This treatment kills crabgrass before it even has a chance. It’s important, however, to know when to apply your preventer. If you apply it too soon, it won’t protect your lawn for the full summer.

But many people assume they should do this by a certain date. Too often, you hear lawn enthusiasts tell you their plans to do it before the first of April or some arbitrary time in the near future.

What they have failed to realize is that crabgrass doesn’t follow set schedules. It doesn’t know your plans. So you should put in your herbicides not by date, but by soil temperatures.

But recent temperatures have made such predictions a little more difficult. Last year, the midwest only experienced temperatures reaching 57 to 64 degrees Fahrenheit in the late Spring.

Another Method to Tell When The Time Is Right

Perhaps easier than taking soil temperatures every day, another method to help decide when the time is right to lay down your preventer is to pay attention to other plants in your neighborhood. Look at flowering trees and shrubs and notice when they are blooming. Typically, before crabgrass even begins to germinate, flowers are in full bloom.

Applying Preventer Correctly

It’s important to get as close as you can to the germination with your preventer as possible. The idea is to try to track down where the seed growth occurs. Be sure and space it out. You want the herbicides to kill new seeds and prevent new crabgrass from growing.

You should apply a preventer before any expected rain, as the water will work it into the soil. If it doesn’t rain, water your lawn after putting the preventer in, letting it wash away both the herbicides and the crabgrass seeds.

It’s also possible to attempt more than one treatment, adding fertilizer along with your pre-emergent or a weed and feed mixture.

What to Do Afterwards: A Post-Emergent

Unfortunately, even the best application of preventer still leaves a few weeds thriving and returning the following year. Giving your lawn a few touch-ups throughout the summer and fall with a post-emergent preventer will help take care of this problem. Also, should you happen upon any stubborn crabgrass growing in your lawn, get rid of it immediately.

The Key to A Good Lawn is Maintenance!

As you can see, there are plenty of ways to help fight crabgrass before, during, and after it grows. But it is a tricky weed, both tough to identify and difficult to get rid of. And the real secret to a healthy, good-looking lawn lies in upkeep and maintenance. And there are a few natural things you do as someone who loves their lawn and garden that helps fight crabgrass already.

Continuing to fertilize your lawn gives it the energy it needs to fight against crabgrass. If you need to fill in those bare spots where crabgrass thrives, an aeration treatment and new grass seed will go a long way.

There are many products on the market that fight crabgrass, with various pre-emergents, post-emergents, and fertilizers.

And they will go a long way in helping you keep your lawn looking fresh. But it all begins with the excellent upkeep you’re already committed to every day.

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