When to Apply Grub Control: Best Timing Guide to Treat for Grubs

Grub damage starts to occur early in spring but becomes more intense as summer approaches. If you don’t treat by applying grub control, you may have the same problem recurring every year. So, what is the best time to apply grub control on your lawn?

The best time to apply grub control is early spring (late March to late April). You can also apply a grub killer when you see signs of grub damage. Grubs turn into adult Japanese beetles from late spring to early summer, which is a good time to put down a grub preventer for the following season.

A good grub preventer contains chlorantraniliprole, a compound that acts on the larvae of the grubs as they hatch. To ensure you have a grub-free lawn, you need to make sure the timing is right for the application.

Best Time to Apply Grub Control

When to apply grub control

Grub control comes in two types – grub preventers and grub killers. Prevention is the best approach to maintaining a healthy lawn, but sometimes, there will already be signs of grub damage in your lawn.

The best time to apply grub control is early spring (April to May) to be able to prevent grub damage that usually occurs in the fall. For grub killers, treat the lawn as soon as you see irregular brown patches of grass forming. You can also put down the treatment in June and July to prevent grubs next season.

Most grubs have a life cycle that lasts one year. Japanese beetles and European chafers turn from pupae into adult beetles during the months of summer. They lay eggs in your lawn which hatch into grubs in the fall.

The newly hatched white grubs feed on the roots your turfgrass, causing brown patches of dead grass. When you see your grass turning brown, this is the time to treat for grubs with a good grub killer such as GrubEx.

  • Grub damage signs start to show from early spring to summer.
  • Prevention should be done a season earlier.
  • Treat for grub damage by putting down grub killer when you see patches of dead grass.

Early summer, adult beetles emerge from the soil when the cycle is complete. They lay eggs in the lawn, which hatch within two weeks. At this time, the newly-hatched grubs start to cause damage to your lawn until when the temperatures drop in the winter when they go dormant deep in the soil.

How often should you apply grub control?

White grub worms are the most destructive to lawns because they feed on roots, leaving the grass dead and turning brown. You’ll need to apply grub control as per the stage of infestation in your lawn. But how often should you apply grub control?

Grub control pesticides can be applied up 2 to 3 times per year depending on the season and stage in the life cycle of the grubs. Put down grub killers when you see irregular patches of dead grass, and apply preventive treatment early in spring and also during fall to eliminate the pests completely for the next couple of seasons.

In brief, you need to apply grub killer as soon as you see signs of grub damage in your lawn, and then put down a grubworm preventer to prevent grubs from damaging your lawn next season.

Do I need to apply grub control every year?

You don’t need to treat for grubs every year because a preventive pesticide application should kill a majority of the grubs that are likely to cause damage the next year. Grubs in your neighbor’s lawn are unlikely to spread to your lawn every year, so only treat when you see the signs of grub damage.

In fact, a healthy lawn can tolerate a few grubs here and there without showing any signs of damage. You only need to start treating the lawn with a grub killer when you see irregular patches of dead grass and also put down a grub preventer as a precaution for the next year.

For prevention purposes, put down priducts with either thiamethoxam, imidacloprid, or chlorantraniloprole once every 2 years early in the spring. Follow the instructions on the product label to guide you on the right time to apply the grub control pesticide because some products last longer in the soil than others.

When is it too late to treat for grubs?

It is too late to treat for grubs in late summer (September) because white grubs will have turned into adult beetles that are hard to kill. Even spraying a grub killer on the lawn may not kill 60% of the beetles that are already feeding on the forage and laying eggs in your lawn.

However, it will only be too late to put down a grub killer pesticide when the grass is already dead because you’ll not be able to revive the grass that’s been dead for more than 5 weeks.

Apply the grub killer when the grubs are actively causing damage to your lawn. It won’t take any timing to do that. The application that needs precise timing is that of grub preventer because it needs to be in the soil before or when the eggs hatch into larvae (white grub worms).

Can you apply GrubEx before it rains?

GrubEx is best applied before it rains because the water from the downpour will wash the insecticide into the soil. Grubs live about 2 inches into the soil and this is where you need the treatment to reach.

The best practice is to put down grub control granules or dust and then water the lawn to ensure the treatment kills grubs that are cutting the roots of your grass. You can also time to apply the grub killer just before it rains, but first make sure it is forecast to rain in your area in the next few hours.

Pro tip: I recommend mowing first before applying GrubEx or any other grub killer to ensure most of the pesticide penetrates down into the soil to kill grubs that are damaging your grass.

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