The Best Time to Apply Scotts GrubEx: Insect Control and Grub Killer

Kenneth Wilson

Unfortunately, some lawn pests can wreak havoc on your turfgrass without tell-tale signs. One such pest, in particular, is grubs– which are notorious for munching on the roots as they thrive underground. Left untreated, they may eventually end up killing your entire lawn and leave it ruined in a single season.

Luckily, the Scotts GrubEx is a popular, specialized product formulated to eliminate Japanese beetle larvae infesting your lawn. One application can prevent grubs all season long. It is formulated with the active ingredient chlorantraniliprole, which kills off any emerging larvae to mitigate extensive grub damage.

We keep in touch with several homeowners daily, and they ask us questions such as: "When is the best time to apply Scotts GrubEx?" and "How do I apply Scotts GrubEx?". So if you’re one of the many with the same question– we’re here to provide helpful information so you can make the best use of the crowd-favorite Scotts GrubEx.

Product Overview

Product specifications of Scotts GrubEx:

  • It prevents insect root damage and gives you a stronger, healthier lawn.
  • It prevents extensive turf damage by eliminating grubs when they’re still young.
  • It kills 25% more common lawn types than the original GrubEx formulation.
  • A single application of the Scotts GrubEx during the spring or early summer can eliminate and prevent grubs on your lawn for four months.

Treating Your Lawn with GrubEx

According to the Scotts Company, you must treat every 1,000 square feet of lawn with at least 2.87 pounds of GrubEx annually. You can use a drop or rotary spreader to ensure an even broadcast of the granular pesticide. Once the application has been completed, opt to water your lawn to ½ inch depth (20 to 30 minutes of watering). Note that the GrubEx won’t be activated until it is watered in.

After the lawn dries, you can allow the rest of your family and furry friends to reaccess the yard. Homeowners dealing with a severe grub infestation and extensive lawn damage may want to look into replacing the turfgrass through seed, sod, or sprig immediately after the GrubEx treatment.

Applying Scotts GrubEx: Timing is Key

The answer to the question of “When to apply Scotts GrubEx?” is during spring or early summer. This allows the pesticide to kill developing grubs. The GrubEx is also effective in controlling Japanese beetle and Armyworm infestations.

It is formulated to focus on the larval stage of several insects, so it’s best to apply it around the time beetles burrow into lawns to lay their eggs (in the spring or early summer months). Once the eggs hatch, GrubEx eliminates the young larvae so they won’t mature. When used as a preventive, the GrubEx features a residual action for up to four months after the application. (Related: When is the Best Time to Treat for Grubs on Your Lawn?)

Important Note: Any mature grubs that overwinter from the previous season may be unaffected by the application in the following season.

Other Key Features of Scotts GrubEx

Let’s discuss the other key features of the Scotts GrubEx, as stated on the official product listing page.

  • Apply in spring to early summer: One fool-proof way to prevent pesky grubs from damaging your entire lawn is by using the Scotts GrubEx Season Long Grub Killer. It kills 25% more common lawn grub types than the original formulation.
  • Provides protection for 4 months: A single application is enough to kill any active grubs and provide adequate protection for the next four months. Ideally, apply it on a dry lawn and water the pesticide thoroughly to ensure activation.
  • Annual use helps control Japanese beetle infestations: Grubs and other notorious lawn pests can damage your lawn extensively by feeding on the grass and its roots. Fortunately, GrubEx can effectively handle the following insects:

White Grubs (including larvae of):

Caterpillars (such as/including):

Aphodius spp.
Asiatic garden beetles
European chafers
Green June beetles
Japanese beetles
May/June beetles
Nothern masked chafters

Sod webworms
Annual bluegrass weevils
Billbug grubs
Crane fly larvae
Chinch bugs

How to Apply Scotts GrubEx

First, set and fill the spreader. Then, apply it to a dry lawn. Water thoroughly (approximately 1 inch) to activate the chemicals in Scotts GrubEx. Lastly, post-application clean-up, if you see any residue on the hard surfaces of your lawn, sweep it away.

Frequently Asked Questions (FAQs)

What is the best time to treat for grubs using Scotts GrubEx?

Precision in timing and application is crucial, so it's essential to follow the instructions on the GrubEx packaging carefully. The best times to use this product are the early part of May, June, and July. Keep in mind that beetles lay eggs during the start of the summer. In the middle of the summer, small grubs may also begin to hatch. GrubEx helps prevent the maturity and hatching of eggs, so it is ideal for applying it in the late spring and ensuring that it is applied in the soil throughout the middle of summer. A single application will last for around four months.

How quickly does GrubEx work?

GrubEx is not used for killing grubs; everyone needs to understand. This product prevents eggs from maturing, so it takes effect when the eggs are already laid. Just be sure to apply it before the beetles start to lay eggs.

Is it a good idea to apply GrubEx in the fall?

The simple answer is no. It's crucial to avoid using the product at the incorrect time of year. For instance, if you use it in the fall, it will no longer work in the early spring. In addition, you must not apply it when you expect heavy rain because the product will just be washed away and won't be as effective anymore.

Is it possible to apply GrubEx and fertilizer at the same time?

While both treatments should be used simultaneously, applying fertilizer when you reseed your lawn or laying down new sod and applying GrubEx separately is advisable. In the fall or the early spring, fertilize and restore your turfgrass. (Related: Best Fertilizers for Bermuda Grass: A Buyers Guide 2022)

Is GrubEx safe for vegetable gardens?

Remember to read and comply with the product instructions carefully. GrubEx is strictly used for lawn care only.

Is Grub control necessary annually?

It's theoretically possible to completely eradicate Japanese beetle grubs from your lawn for one year and ensure that they won't return the following. However, this is not very likely. Just one or two Japanese beetles are needed to lay many eggs and yield a large number of grubs. Your best option is to include the application of GrubEx into your yearly lawn care routine because it does not have a repelling effect on the beetles.

How should GrubEx be applied?

The pesticide should be applied evenly over the surface of your yard at a rate of 2.87 pounds per 1000 square feet using a rotary or drop spreader. (1) Irrigate your lawn thoroughly to help the product take effect, (2) water it for about half an hour with a depth of around half an inch, and (3) wait for the water to soak in and the grass to dry before letting pets and children on your lawn.

How can you tell there are grubs in your lawn?

Large expanses of dead, brown grass will quickly become visible if the grubs take hold, but you don't want to let it get worse. Developing a habit of closely and frequently examining your lawn is essential to spot the early signs of problems. It is the only way to determine the best time to apply GrubEx. These three signs of grubs are what you must watch out for:

  • Brown, dry spots ─ Your grass may dry out, wilt, and turn brown due to a lack of water during the hot summer months or drought, but if this happens during the cooler, rainy months, you should suspect grubs or other underground pests like moles and voles.
  • Damage in sunny areas  Grubs prefer to be in areas with warm soil. Check for grubs if you find that your lawn's south side appears to have more damage than other parts.
  • Beetles ─ In the early summer, you can tell that beetles are laying eggs if you observe them stumbling around in your grass or flying close by. If you don't currently have grubs, you soon will.
Kenneth Wilson
July 19, 2022
2terra, Reviews, Yard & Garden

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

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