When To Apply Crabgrass Preventer

Crabgrass preventer is commonly used by homeowners to keep this weed from invading their lawn.

But when to apply crabgrass preventer is the best? In this blog post, we will discuss the benefits of using crabgrass preventers and when the best time to use them is.

Keep on reading “When To Apply Crabgrass Preventer” to find out!

What Is Crabgrass?

Crabgrass is the popular name for a plant genus (Digitaria) that comprises both annual and perennial types of grass. The species’ blades are normally wide and flat, and they produce lengthy flower clusters and millions of seeds every growing season.

Crabgrass maintains a low profile on the lawn, avoiding the mower blade during mowing. And, unlike taller weeds, it has little that can “break,” so it can withstand foot movement even in high-traffic areas.

The one plant element on the weed that sticks out—the stem that bears flowers and, eventually, seeds—is resilient and doesn’t mind being trampled on.

Crabgrass has the appearance of a coarse, light green clump of grass. Its expanding stems resemble crab legs. It is frequently confused with fescue grass, however color and size are important distinguishing factors. Tall fescue grass is an often deeper green, dense, and grows quickly.

Young crabgrass blades are roughly the thickness of a pencil, but the stems get heavy, fall, scraggly, and have a star-shaped pattern in the center.

When To Apply Crabgrass Preventer

Crabgrass is a tough grassy plant that may be successfully managed with a good pre-emergent herbicide applied at the correct time. Crabgrass germinates when temperatures begin to rise in the spring. When should you use a crabgrass preventer on your lawn?

The optimal time to apply crabgrass preventer is in early spring when soil temperatures reach 55°F. This is the best time when to apply a crabgrass preventer. Apply pre-emergent right before raining to ensure that the herbicide is rinsed into the soil. When dogwood and forsythia bloom, it’s time to start spraying crabgrass preventers.

Signs The Timing Is Right For Putting Down Pre-emergent

We don’t always know if our timing is correct. The arrival of spring might be hazy, leaving you perplexed and unsure of when to plant your pre-emergent.

Here are a few indicators to assist you to decide when to apply crabgrass preventer:

Soil Temperature Rising Above 55F

Temperatures begin to climb as winter ends and spring arrives. Crabgrass and other weeds become active and begin to germinate at this time.

If you begin taking soil temperatures, you should aim for 55 degrees Fahrenheit. Crabgrass seeds will germinate when the soil temperature reaches this level.

When the soil temperature is at least 55°F or above at a depth of 1 – 2 inches for 3 days straight, a crabgrass preventer should be applied. Crabgrass seeds, in fact, will germinate when the soil temperature is between 60°F and 70°F.

  • Moisture, wind, and sunshine may all have an impact on the temperature of your lawn’s soil.
  • When compared to regions that receive full sunshine, the temperature of the soil in a gloomy lawn might fluctuate.

When assessing the temperature in your yard, you should take these two elements into account.

As a result, you should begin measuring soil temperatures on your lawn in early spring (and in strategic locations) to determine the best time to apply the pre-emergent herbicide. For this, you’ll need a dependable soil thermometer.

Dogwoods And Forsythia Blooms

From mid-March until mid-April, forsythia shrubs begin to flower. After a long, frigid winter, temperatures begin to increase, signaling the arrival of spring.

If you notice a cascade of beautiful yellow forsythia blossoms, it is time to use crabgrass preventer herbicide to prevent weed germination.

If you don’t have any forsythia shrubs in your neighborhood, you can substitute dogwoods.

Dogwoods bloom from late March to mid-May and have sweet white blossoms. When you observe these blossoms, it is still a good time to apply a pre-emergent herbicide to your lawn to prevent crabgrass from growing.

Late February – Early April

The spring calendar is another useful signal to keep in mind when deciding when to apply crabgrass pre-emergent.

Because spring does not begin on the same day every year, a seasonal calendar can assist in determining the optimal time to apply a crabgrass pre-emergent herbicide.

Hope the information has helped you know when to apply crabgrass preventer.

Types Of Crabgrass

Unfortunately, there are always some annoying weeds that survive the late spring pre-emergent pesticide application. Throughout the summer, apply post-emergent to your lawn. Crabgrass may be controlled by applying postemergence herbicides to weeds that appear on your lawn.

If you notice any crabgrass development, act quickly. Weeds that are actively growing are easier to eradicate than mature weeds. Check your lawn for new weeds when mowing to capture actively developing weeds early.

Hairy Crabgrass

Hairy crabgrass is also called long crabgrass. Their leaf blades are around the same length, reaching up to 6 inches in length, while hairy crabgrass grows longer than smooth crabgrass.

The hairy kind (Digitaria sanguinalis) gets its name from the fact that its leaves and stems are covered with microscopic hairs. It has coarser and wider blades than smooth crabgrass.

Hairy crabgrass leaves can be up to 1/2-inch broad, whereas smooth crabgrass leaves are around 1/4-inch wide.

Smooth Crabgrass

Smooth crabgrass (Digitaria ischaemum) has no hairs around the sheath or the leaves. Smooth crabgrass has hairs exclusively at the plant’s auricles, which are tiny, ear-like projections on the inside side of the leaves at the base.

Because it grows shorter, smooth crabgrass is sometimes known as “little crabgrass.” While it can reach 6 inches in length, it is usually shorter than its hairier relative. The leaf blades of this plant taper to a point. The plant’s stems bend at the nodes and occasionally become crimson.

What Is Crabgrass Preventer?

When applying a crabgrass preventer, you may need to consider the type of preventer that you need!

Pre-emergent Crabgrass Preventer

Pre-emergent herbicides are the most often used method for controlling crabgrass. The application period varies because, as previously said, the soil temperature must be just correct before using pre-emergent.

Pre-emergents are designed to prevent crabgrass from emerging from the soil. If the pre-emergent is applied too early, the crabgrass will not be controlled throughout the season. This is why it is critical to apply the pre-emergent after the crabgrass has begun to sprout.

Post-emergent Crabgrass Preventer

Unfortunately, there are always some annoying weeds that survive the late spring pre-emergent pesticide application. Throughout the summer, apply post-emergent to your lawn.

Crabgrass may be controlled by applying postemergence herbicides to weeds that appear on your lawn. If you notice any crabgrass development, act quickly.

Weeds that are actively growing are easier to eradicate than mature weeds. Check your lawn for new weeds when mowing to capture actively developing weeds early.

Why Do You Need To Prevent Crabgrass?

If you have crabgrass in your yard, then you know what a pain it can be. It’s hard to keep up with and very difficult to get rid of. If you don’t prevent it, then it will spread like wildfire across your lawn.

So why do you need to prevent crabgrass? Well, for starters, it looks awful. And not only does it look terrible, but it can also damage the integrity of your lawn by causing divots and holes.

That’s because crabgrass is shallow-rooted and grows quickly. That makes it susceptible to drought and other environmental factors that affect the growth of other grasses as well.

If left untreated, crabgrass will spread throughout your entire lawn and make an even bigger mess than it already has. It’s important that you take care of this problem immediately so that you don’t have any more problems later on down the road.

How To Apply Crabgrass Preventer

Once you’ve determined the best time to apply a crabgrass pre-emergent, you’ll need to make sure you’re ready.

The majority of preventive remedies will be liquids that must be administered using a backpack or hand-held sprayer. Some are water-soluble and should be used in the same manner after being mixed.

Always read and observe the instructions – when combining or diluting, be cautious not to increase the dose, since this can be hazardous to turfgrass.

Check that the grass is not already moist on the day of application. If there was a lot of dew in the morning, wait a few hours until the grass is dry again.

In this manner, the solution penetrates the soil rather than merely sticking to the grass blades. Remember that moisture following application will only aid in the solution’s absorption into the soil.

Begin spraying from one end of the yard to the other in equal strokes. Make careful to get the lawn’s edges as well. Crabgrass prefers to thrive in the warmest soil (near pavement or concrete).

Use all of the precautions recommended on the label, and avoid allowing traffic on the lawn for the whole day.

FAQs Related To When To Apply Crabgrass Preventer

Can You Apply Crabgrass Preventer On Wet Grass?

You can apply a crabgrass preventer on wet grass, but you may not be getting the benefit of the product if you do it this way. The problem is that a lot of the granules will simply wash away before they can work their way down into the soil.

However, if you wait until the ground is dry and then apply it, there’s no need to worry about it washing off right away. This makes sense because if your lawn needs to be watered often, then it’s likely that it also needs to be fertilized often as well.

In addition, when you use a crabgrass preventer on wet grass, you run the risk of burning your lawn if it rains within 24 hours after application.

This is because the weed killer contains an ingredient called sulfentrazone (Avadex), which can cause damage if exposed to water for a long period of time after application.

Can You Put Down Too Much Crabgrass Preventer?

A lot of people have asked me whether it is possible to over-apply crabgrass preventer. The answer is yes, you can put down too much of it.

The product is designed to be used at the correct rate. If you put down more than what is recommended, then you will end up wasting a lot of money and you may not get the results that you desire.

If you want to be sure that you are using the right amount, then make sure that you read the instructions on the label. You should also check out this video where I talk about how much crabgrass preventer to apply in the spring:

Can You Put Down Crabgrass Preventer And Fertilizer At The Same Time?

Crabgrass preventers and fertilizers can be used at the same time. The crabgrass preventer will not harm your lawn, but if you use a fertilizer that contains nitrogen, it may encourage crabgrass to grow in your lawn.

If you want to use both a crabgrass preventer and fertilizer in your yard, it’s best to treat the areas separately. This means that you should spread the fertilizer on one day and then apply the crabgrass preventer on another day.

It’s possible that the fertilizing process will create excessive moisture in your yard, which may cause some of the chemicals from the crabgrass preventer to wash away before they’ve had time to work properly.

Will Crabgrass Preventer Kill Existing Crabgrass?

The answer is yes, crabgrass preventers will kill existing crabgrass. The question is whether they will kill all of it or just some of it.

If you use a weed and feed that contains a pre-emergent herbicide (the chemical used to prevent weeds from germinating), then you can expect the following:

The pre-emergent herbicide will prevent new crabgrass seeds from sprouting on your lawn. This means that if there are any new crabgrass seeds that have germinated since you planted your grass, they will die once they start to grow.

The pre-emergent herbicide will not kill existing crabgrass plants. So if there are any existing crabgrass plants on your lawn, they won’t be affected by the chemical compound in the weed and feed.

How Long Do Pre-emergent Herbicides For Crabgrass Last?

Pre-emergent herbicides are applied just before the lawn is planted or sodded. They contain active ingredients that prevent crabgrass from germinating before you have a chance to seed your lawn with grass seed. This gives the grass seed a head start on the competition.

The pre-emergent herbicides will last up to 90 days, depending on the type of product you choose. A single application should be enough to kill any crabgrass that tries to germinate on your lawn during this time period.


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