You’ve already read up on the ways you can kill grubs in your lawn. Let’s discuss when you should use each of the potential treatments, both chemical and natural. Like many other things you do in life, timing is everything. Doing a lawn care task at the right time of year can make the difference between success and failure, so in this article, I will share when to apply grub control – explaining the right time of year to perform this task for different treatments.
The time of year you treat your lawn for grubs is crucial, as you need the right kind of weather to get the best possible results.
I’ll explain the exact weather conditions you are looking for (or need to create with a hose), so you can rid your lawn of these grass-destroying pests.
But first, let’s look at what grubs are and learn a bit about their life-cycle. Understanding how different types of grub develop in your turf will inform when you need to apply grub control to your yard.
This article was last updated on by Lawn Chick Owner Sarah Jameson
Article content reviewed for accuracy by Horticulturist Arthur Davidson, A.S.
First, What are Grubs?
Grubs, or grubworms, are species of insect such as billbugs, June bugs, and European chafers after they hatch.
These bugs lay their eggs in soil, and after they hatch they eat what’s there … meaning that grubs in your lawn will begin devouring the roots of your grass (which kills it).
They do this during the warm weather.
Grub Infestation Symptoms
If you’re unsure whether you have a grub problem in your lawn, there are certain signs to look for. Let’s take a look at them below:
- There is a spongy texture or quality to your lawn. You might have noticed this when stepping on the grass. Have you ever walked on newly installed sod? That is a bit like the sponginess you’ll observe in your lawn if you have a grub problem.
- You find a dead patch on your lawn. Try to pull the grass back. If you can do this easily, it might be because grubs are compromising the grass roots … and that was the cause of death of your turf.
- Birds and mammals like skunks and raccoons seem especially attracted to your property. You will notice them digging, trying to get grubs. This is a tasty snack for many animals.
When Should You Apply Grub Control?
The early months of the spring and late months of the summer are the best times of year to apply grub control. Why? It’s because it’s during those times of year when grub worms are most active on your property.
- If you want to prevent grub problems (but don’t currently have one) – If you’re going to use a grub preventer (rather than a treatment), you should do so in June or July. For many species, this time period is immediately prior to their annual hatching period.
- If you have a grub problem you need to treat – You should apply grub killers starting in the spring. Do it when you begin to notice grub damage on your lawn. This will usually take the form of brown patches.
The fastest way to stop grubs from damaging your lawn is to use insecticide meant for killing grubs.
I recommend that you do this the moment you notice any damage on your lawn.
In most cases, this should be done sometime between the early parts of the spring and early August, but the exact timing will depend upon your local climate, and the species of insect laying eggs in your lawn.
Don’t Apply Grub Control Too Early
Applying grub control to your lawn too early will be a waste of time and product.
That is because the pesticide will no longer have any efficacy by grub-hatching time, which takes place in July and August.
What Should You Do After Grub Control Pesticide Application
Once you have put down grub control pesticide on your grass, there are some other things you should do.
These include immediate wearing and then keeping an eye on the area, to make sure there isn’t any grub activity.
You should apply water to your lawn right after applying grub control. This is especially important if you are using a granular type of grub preventer or grub killer.
If you are using a granular formula, apply a minimum of an inch of water. If you don’t do this, a granular formulation won’t be effective.
Remember to keep an eye on your lawn after, to make sure the grub control is working. You might still see some grubs right after, as some products will take as long as a week to work.
If you still see a problem after that, the treatment wasn’t effective. You possibly didn’t use the correct amount, or you need to try something else.
You can calculate your lawn’s square footage right here to be sure you apply the perfect amount of product to the impacted area of your yard.
Your Problem Might Not be Grubs
While grubs are a common lawn problem, you should know that other issues can present lawn damage similar to that caused by grubs.
Before you treat your lawn for grubs, you should try to make sure that you indeed have a grub problem on your lawn.
Digging In
The best way to do this is to get out the spade or a small gardening trowel.
If you have noticed dead patches on your lawn, take a sample of the turf. Your turf sample should be a couple of inches in depth. Examine the sample to see if you can spot any grubs.
If you have a big issue they should be obvious, but if you don’t see any, sample a few other areas to confirm there are no grubs present.
Remember that a host of different lawn problems can cause brown patches on your lawn. Don’t jump to conclusions and assume it must be grub overpopulation. You will need to check the soil and examine it to see how many grubs there are.
Your Lawn is a Buffet for Critters
Another sign of a potential grub infestation is holes in your lawn. These will be from small animals like moles digging in your lawn to get and eat the grubs.
If you think you have a grub infestation, you will need to find out how serious the infestation is. One way to do this is to pull back a bit of the turf and see how many grubs are in the ground.
You should do this in more than one area, to see if certain parts of the lawn have a worse problem than others. Make each space one square foot, and count how many grubs you see with each. If you see more than five of them in each square foot area you check, your lawn will benefit from treatment.
A Few Grubs is Nothing to Panic About
Be aware, too, that it’s perfectly normal for lawns to have a small number of grubs. Don’t assume you need to treat your lawn just because you’ve noticed a single grub, or what appears to be a more limited issue.
As long as the population stays low, you shouldn’t end up with any lawn damage, and you can avoid spreading insecticide.
Keeping your yard healthy through proper lawn maintenance should help prevent the development of grub overpopulation.
Expert Advice Regarding Grub Numbers in Lawns
David Smitley et al. at Michigan State University MSU Extension Turf explain that “Healthy turf with a few grubs may not need an insecticide. It is important to realize that healthy turf, supported by frequent rain or irrigation, can support a grub population of five or more grubs per square foot with no visible turf damage.”
As long as your lawn’s grub population stays low and the grass is healthy, you probably don’t have to do anything to get rid of the grubs.
As long as you don’t see more than around five grubs for each square foot of grass you lift, you won’t have to take any kind of grub control measures.
Expert Tips Regarding Japanese Beetle Grubs
Gary Forrester, a Horticulture Extension Agent at Clemson University, explains that the Japanese beetle is mainly found “east of the Mississippi River except Florida.”
If you live in South Carolina, there is a very strong chance you could end up with Japanese beetles in your soil. This species was introduced to the United States, meaning it isn’t a native species.
Some Thoughts Based on My Experience
I get a lot of emails from readers in different parts of the country about grubs and how to deal with them. One that stands out was from a reader in Florida with a severe grub problem, concerned that the product they had applied (and re-applied) had done nothing to reduce the grub infestation in their lawn.
It turned out they were using a product that targeted Japanese Beetle grubs, when in fact those insects aren’t common in her area.
The Take Away – It’s important before you buy a grub product to understand the species common in your part of the country, and to choose a product that will successfully address that insect population.
How to Prevent a Grub Problem and Maintain a Healthy Lawn
As mentioned earlier, keeping up a healthy and well-maintained lawn makes you much less likely to end up with a grub overpopulation problem.
Appropriately fertilize, water, and aerate your lawn at the right times. If your lawn ever ends up under-nourished or impacted by drought, it’s much more likely to have higher levels of grubs for each square foot of turf.
Once you’ve dealt with your grub problem with your chosen product, you can use other products to bring your dead patches back to life.
You can do this with re-seeding or overseeding, and using proper fertilization.
Also, if you have had a confirmed grub issue in your lawn, it’s a good idea to get on an annual grub prevention schedule, applying that product in June or July every year.
What Kind of Grub Control Should You Use?
There are options when it comes to grub control on your lawn, and you can go the natural route or chemical. There are pros and cons of each type of product which I’ll touch upon here:
- Organic – Beneficial Nematodes (worms) or Milky Spore (bacteria)
- Chemical – Insecticides that target grubs
Nematodes
A popular natural choice is Nematodes. These are tiny worms which are parasitic and will attack the grubs, eventually destroying them. If you want to use Nematodes, usually all you have to do is put them in water, shake, and then put them on the grass.
It’s a natural way to combat grubs, and they won’t harm you, your family, pets or beneficial things like your native earthworms, the only trick is being ready to apply them as soon as you receive them (they’re a living organism and could die otherwise).
This is the Nematode product I recommend, on Amazon.
Milky Spore
Milky Spore is a tried and true method of killing lawn grubs – in particular grubs from Japanese Beetles. It’s a bacterial treatment which is natural and harmless to humans and pets (unless you breathe it in during application, which is why I recommend this granular version for lawn spreader application).
Be aware that is a slow-acting option, though. You’ll want to apply this in the spring, summer, and fall for two years. Once you do that, you can expect your lawn to remain grub-free for up to 20 years.
It’s a great long-term, natural solution.
Insecticides
The easiest (but least safe for kids/pets) is to use chemical insecticides that target grubs. This can be a good solution if you have a very bad case, or plan to stay off your lawn for a while after application (you can do it right before you take your annual beach vacation).
There’s some risk to beneficial insects in your lawn’s ecosystem with this method, so you really have to weigh the pros and cons.
Popular Options:
- Scotts GrubEx (widely available consumer option)
- Arena Insecticide (commercial grade option)
No matter what kind of grub control you use, don’t let pets or children on the lawn for a safe period of time.
If you use chemicals, this will be a longer time period. Check the instructions that come with your grub control product.
Take Care of Your Lawn
If you already have a grub infestation, take steps to deal with it. If you have a normal number of grubs and want to avoid an infestation, take proper care of your lawn and keep it healthy (my free cheat sheet gives you a plan and schedule to follow).
I always say the best defense against weeds, insects, and other lawn pests is a good offense.
If your lawn is thick, resilient and healthy, it will be less attractive to beetles and bugs trying to find some open soil to lay their eggs on/in.
At Lawn Chick, I am committed to publishing accurate, useful, and trustworthy resources for my readers. As part of this commitment, I’ve invited subject matter experts to review our articles for accuracy. I invite you to read our editorial policy and publishing standards which outlines in detail how every article on this site is sourced, edited, fact-checked, and vetted.
-Sarah
Additional Resources
- How to choose and when to apply grub control products for your lawn by David Smitley, Terry Davis, and Erica Hotchkiss, Michigan State University, Department of Entomology (link)
- White Grub Management in Turfgrass by Gary Forrester, Clemson Cooperative Extension Home & Garden Information Center (link)
- White Grubs in Home Lawns by Paul Heller, PennState Extension (link)
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