When to Apply Grub Control [Best Time to Treat Your Lawn]

Knowing when to apply grub control is crucial to protect your grass. Grub activity and damage become noticeable around May, following the feeding program that you started in early spring.

Quick Answer

The best time to apply grub control is any time from mid-summer through September when there’s increased grub worm activity in your lawn:

  • For grub preventers, apply between May through mid-July when grubs are ready to hatch
  • For grub killers, apply the treatment from mid-summer when you see signs of grub damage in the grass.
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Grubs LifeCycle

grubs eating grass roots

June bugs, billbugs, and European chafers usually lay their eggs in lawns and gardens. As soon as they hatch, they develop into grubworms and start eating the grassroots throughout the warm seasons.

You’ll notice signs of dead patches of grass any time from early spring to mid-summer when the damage stops due to the grubs having developed into pupae and adults. However, dead patches of grass can also be caused by improper lawn care practices.

So, throughout this life cycle of Japanese beetles and European chafers, what is the best time to treat your lawn for grubs with a preventer or a killer?

When to Apply Grub Control?

The best time to apply grub control depends on:

  • Whether you’re preventing them for next season, or
  • killing the ones already damaging your lawn.

You only need to start a grub control treatment when you see signs of damage.

If you feed your lawn properly, your grass can support about 5 grubs per square foot of turf without any visible damage. Your lawn will still look green and healthy because the damage from their feeding activity will be very minimal.

When to apply Grub Control and killer

Apply Grub Preventers

It is usually best to put down grub preventers before you first see signs of damage. This will provide the best preventative control of grubs for the next season.

You need to apply the insecticide between May and July to prevent infestation for the next season by killing and harming the development of the next generation of grub worms in your lawn.

You cannot apply a grub preventer to kill grubs that are already damaging your lawn. If you’re applying a grub preventer, it will not get rid of grubs that may be present in your lawn from mid-October through the middle of May.

But, when is it too early to apply grub control?

When treating your lawn to prevent grub damage for the next season, it would be too early to apply a grub preventer on your turf in early spring.

The pesticide will easily disintegrate into the soil and lose its potency by the time the grubs hatch in July through August.

According to the Colorado State University Extension, “insecticides are best used in ways that allow them to be in high concentration in the root zone at the same time eggs are hatching and young white grubs are present.

When timing is done right, you’ll be able to control about 80 percent of the grubworm infestation in the next season.

Apply Grub Killers

grub damage in lawn

If you want to stop grub damage immediately, the best time to apply grub killer insecticide to your lawn is as soon as you see signs of damage. This is usually any time between mid-summer through September when the grub larvae feed the most, and are most active eating and damaging grass in your lawn.

Pro tip: Some grub control pesticides such as Scotts GrubEX provide long-term control and can be applied almost any time of the season. It can kill adult beetles and reduce their population in your yard.

Scotts GrubEx1 Season Long Grub Killer, Protects Lawns Up to 4...
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Scotts GrubEx1 Season Long Grub Killer, Protects Lawns Up to 4...
  • Scotts GrubEx1 Season Long Grub Killer can help prevent turf damage by killing grubs when they are young
  • One application of this lawn care treatment kills and prevents grubs for up to 4 months
  • This grub killer also controls caterpillars (armyworm), chinchbugs, May/June beetles, and more (as listed), and can help control Japanese beetle infestations when applied annually

Affiliate links and images pulled from the Amazon Product Advertising API on: 2024-05-27

How & When To Treat Grub Worms In the Lawn

For the grub killers, you can stop lawn damage almost immediately especially if you follow the right application guidelines on the label of the pesticide. There are several different ways to apply pesticides to kill grubs on your lawn.

How Often Should You Apply Grub Control?

how often to apply grub control products

Grub treatments are effective when applied at the right time. In some cases, you may need to apply the pesticide two or three seasons in a row to completely eradicate grubs in your lawn.

In most cases though, you’ll only need to apply grub control twice in a season:

  1. The first one being a grub killer when you see signs of infestation, and
  2. The second one being a grub preventer from May to July to stop their cycle for the next season.

Do You Need to Apply Grub Control Every Year?

Do you need to apply grub control every year?

You do not need to apply grub control every year successively unless you see grub damage. If you’ve been treating your lawn with a grub preventer and killer for a few years in a row, it may be time to stop until you see the signs of grubs and European chafers again.

However, if you found grubs in your lawn last spring, then you may need to apply a grub preventer for lawns this year.

Note: In healthy turfs, a few grubs should not be a problem and you may not need to apply insecticide every other year.

What to Do After Putting Down Grub Control Pesticide

You want to get the best effects after applying the pesticide on your lawn. Here are a few tips on what to do after the application:

  • Water your lawn immediately after putting down grub control: Most grub killers and preventers come as granular formulations. For them to be effective, water your lawn to at least 1 inch.
  • Monitor your lawn for grub activity after treating it. After applying a grub killer, you can expect eradication to happen within a few days to a week. If the damage continues, it is likely the grub treatment was not enough or did not work.

Types of Grub Control

There are two types of grub control products – preventive chemicals and curative chemicals, and here’s the difference between the two to help you make the right choice.

Preventive Chemicals

Preventive chemicals are those that prevent pests from becoming established before the situation spirals out of control. If applied properly, preventive herbicides can be very effective against the growth of grubs.

ProductsIngredientsWhen to Apply?
BonideimidaclopridApply the product every 8 weeks during the growing season
TandemLambda-cyhalothrin and thiamethoxamJune or July and watered-in with 0.5 inches of irrigation
AcceleronClothianidinJune or July and watered-in with 0.5 inches of irrigation

Curative Chemicals

Curative chemicals kill grubs that are already in the soil at the time of application. They work by working their way down through the soil and kill grubs upon contact.

ProductsIngredientsWhen to Apply?
DuoCideBifenthrin and carbarylKills 20-80% of grubs when applied in September or 20-55% when applied in late October
TrichlorfonTrichlorfonKills 20-80% of grubs when applied in September or 20-55% when applied in late October

What to Look for in Grub Preventers

Most homeowners mean to kill grubs when they see signs of infestation. However, the best way to control their damage in the long-term is by putting down a preventer.

A good grub control preventer will contain any one of these active ingredients:

  • Imidacloprid
  • Chlorantraniliprole
  • Thiamethoxam
  • Clothianidin

The reason why you want to look for these ingredients is that they are very good at killing grubs at a tender age, usually as soon as they hatch.

Ingredients that DO NOT Work On Lawn Grubs

There are a few active ingredients in grub control products that simply don’t work. Products that only contain the following won’t be effective in killing grubs:

  • Lambda-cyhalothrin,
  • Gamma-cyhalothrin,
  • Bifenthrin,
  • Deltamethrin,
  • Cyfluthrin, or
  • Permethrin

Adding to this, there are a few curative products that are only effective in eliminating grubs when applied at the right time (late summer and fall):

  • Carbaryl,
  • Trichlorfon, or
  • Zeta-cypermethrin

Read the product label carefully to determine the active ingredients and follow the manufacturer’s instructions on application procedures.

Best Grub Killer

Best Grub Killer Herbicide

This is my selection of the 3 best grub killer herbicides:

Affiliate links and images pulled from the Amazon Product Advertising API on: 2024-05-27

When to Apply GrubEx

The best time to apply GrubEx is during the spring through mid-summer when grub activity in lawns in heightened. Applying this formula will kill grubs as they develop. As a precaution against future invasions of grubs, you can apply Scotts® GrubEx®₁ Season Long Grub Killer annually, which stops and prevents grubs with a single application.

You can apply GrubEx before the rain, which will water in and activate the product. With regard to application, you can apply GrubEx with a spreader, and then water it thoroughly to activate it or wait for rainfall.

Can Scotts Grubex Be Applied in the Fall?

Fall might not be a very good time to put down grub control. As temperatures continue to drop with winter approaching, grubs dig down approximately 4-8 inches into the soil and lay there until temperatures start to rise again.

You may not get much success controlling lawn grubs and European chafers if you apply GrubEx in October and November, or the duration of fall because it might be too late to treat for grubs.

Homemade Grub Killer Alternatives

Alternatively, a homemade solution for controlling grubs in a lawn is to use Dawn dish soap. It may not eliminate grubs completely, but it can assist in managing light infestations.

You can also use Milky Spore to control bugs and worms in your lawn, but that comes with pros and cons.

Grubs Damage Photos

Grubs Damage Photos
Grubs Damage photo example
chafer grubs emerging from a damaged lawn
Chafer grubs emerging from a damaged lawn
grass seeds growing after grubs lawn damage
Grass seeds growing after grubs lawn damage

Tips Before Applying Grub Control

Here are a few tips before applying grub control to help you get the job done right.

  • First things first – make sure that you indeed have a grub problem before resorting to any treatment methods. There are several telltale signs to let you know that you have grubs strolling in your lawn such as when you actually see grubs, dead patches, spongy spots, hovering moths, and/or more birds, raccoons, armadillos, skunks, or moles coming to pay a visit
  • Since each product varies, it’s important to check the product label to determine the active ingredient. Doing this will also let you whether the product is a preventive treatment or a curative so you can apply it at the right time for the best results
  • Next, do not buy and use products that only contain certain ingredients such as lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin, or permethrin because they do not work on their own towards solving the grub damage to the lawn or grub damage to the garden problem. Follow the instructions like dosage and best time to apply listed in the respective product label
  • Remember, these are chemicals you’re dealing with so make sure you wear protective gear such as safety gloves, safety glasses, a long-sleeved shirt, and long-sleeved pant
  • After spreading the grub control product, irrigate your lawn with at least 0.5 inches of water. Rainfall or irrigation will activate the grub killer and make the application more effective
  • If you have kids or pets that you feel won’t stay off the lawn, consider using a natural grub killer such as nematodes for grubs.


Is It Too Late to Treat for Grubs?

The answer depends on when you add the pesticide. If you apply the pesticide after early October, great chances are that it’s a waste of your efforts. For best results, apply a grub killer between April 1 and May 30 (no later than July 15).

How Long to Water in Grub Killer?

The product label should let you know the amount of time or depth to water the grub killer. But most grub killers ask that you irrigate until you reach at least half an inch of water, which equates to running your sprinklers for as much as an hour.

Do Grubs Die in the Winter?

Unfortunately, No! Grubs lay eggs that hatch and grow until mid-fall, after which they move deeper into the soil to survive the winter season. Grubs burrow themselves underground to wait out the winter and slowly make their way back to the surface to feed when the ground temperatures start to warm to about 50 degrees Fahrenheit.

Can You Apply Too Much Grubex?

GrubEx is a pesticide and applying too much of it will do more harm than good. The instructions on the GrubEx label suggest applying the product once per year, which should protect your lawn against grubs all season long.

Can I Apply Grubex to a Wet Lawn?

You can apply GrubEx before a good rain is heading your way but you should ideally apply GrubEx to a dry lawn and then water thoroughly to activate the product.

Should Grub Killer Be Applied Before or After Rain?

Yes, you can apply a grub killer before the rain, which will activate the product. However, there are some chemicals in certain grub control products that will break down in hot, dry weather.

How Do You Get Rid of Grubs Permanently

The best way to get rid of grubs permanently and quickly is by using chemicals such as carbaryl or trichlorfon if the grubs are already present in your lawn.

Final Thoughts

If you want to get rid of grubs, it’s important to apply a grub control product at the right time. There are two types of treatments for grubs – preventive and curative treatments, where the former should be applied before the invasion of grubs and the latter if your lawn is already plagued with grubs.

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1 thought on “When to Apply Grub Control [Best Time to Treat Your Lawn]”

  1. I have grubs all over my lawn .I can pull up the grass just like a loose carpet. Want to know what is the best treatment to get rid of these pest that are ruining my once nice lawn. When is the best time to start a treatment and what should I use.


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