As the snow melts across the Ottawa Valley, many of us are eager to see a lush, green carpet return to our yards. However, spring often reveals some unwelcome guests hiding just beneath the surface.
If you’ve noticed "spongy" patches of grass or seen skunks and birds treating your front yard like an all-you-can-eat buffet, you likely have a grub problem.
Here’s what you need to know about managing these pests this spring and how to set your lawn up for success!
The Spring Grub Reality Check
In Ottawa, the grubs we see in April and May are the larvae of beetles (like the Japanese Beetle or European Chafer) that overwintered deep in the soil. As the ground warms, they rise to the surface to feed briefly before turning into beetles.
There are a couple of ways to tell if you have an infestation before you noticed damaged turf in the summer.
You can try the "carpet" test. If you've located a part of your lawn that feels "spongy" or looks more discoloured, try pulling up a patch of brown grass as if you were checking under a carpet. If you can easily lift the turf, grubs have likely eaten the root system.
Notice signs of wildlife damage. Holes from skunks, birds, and raccoons are often a more obvious sign of grubs than the grass damage itself.
The most effective way to determine if you have an infestation is to do a Grub count. Peel back a square foot of sod. If you see more than 5–10 C-shaped white larvae, it's time to take action!
SPRING into Action!
While many people wait until fall to treat grubs, spring is the critical time to repair damage and prevent the next generation from taking hold.
1. Nature's best kept secret: Beneficial Nematodes
Nematodes are microscopic worms that are native to Canada. Nematodes are sprayed onto the lawn using a hose-end sprayer and make their way into the grubs as a host. Once they have attached, they infect the grubs with a bacterium that breaks down the grub's tissues. Once the grubs have died, the nematodes reproduce and search for a new grub host. The bacterium that infects the grubs is completely safe for earthworms, beneficial pollinators, and burrowing animals.
Gardeners interested in using beneficial nematodes do need a hose and a hose end sprayer. In ideal conditions, apply nematodes before a couple days of rain, otherwise you will need to keep the grass moist manually (using a hose or irrigation) to help the nematodes flush from the grass blades and into the soil.
We sell nematodes provided by NIC, an Ontario company. They have lots of great additional information on Grub Control, as well as this super useful video on how to apply the beneficial nematodes that we sell!
Check out the video below to see just how easy our beneficial nematodes are to use!
2. Grub B Gon MAX to minimize the grub population
IMPORTANT: This option is not suitable for those with outdoor pets or small children within 8 hours of the application.
Grub B Gon is a granular chemical pesticide that is best applied in early August to the lawn. Grub B Gon is an approved chemical pesticide that "disrupts the nervous system of the grubs, causing them to become paralyzed and die". Grub B Gon is sprinkled onto the lawn before a rainfall (or you can use manual irrigation) to penetrate the soil level and become accessible to the voracious grubs.
Grub B Gon is advertised as a safe chemical for bees and other beneficial pollinators.
3. The Long Game: Building Lawn Resilience
Cultivating a thick, healthy lawn is the best way to avoid grubs because beetles prefer to lay eggs in thin, stressed grass. Spring is the time to strengthen your lawn through overdressing, over-seeding, and applying a high-nitrogen fertilizer to encourage strong growth through the spring.
Start Early! In April, we get lots of rain to help our plants grow. Apply corn gluten to the lawn to prevent weed seed germination and to feed the existing lawn. Weeds, like crabgrass, often harbour more grubs than traditional lawn turf, so eliminating new weeds can help reduce spaces for grubs in your lawn.
Remember, corn gluten acts as a pre-emergent, meaning it inhibits all seeds, including grass. It should not be used when planting new grass seed; you should wait 6 weeks after application to over-seed your lawn.
In mid-May, after the soil has reached a consistent 15 degrees celsius, apply a generous cover of top soil or black earth to areas in your lawn where the ground is tough, uneven, or cracked. Next, using a spreader to ensure an even application, spread grass seed. Remember to consider shade, sunlight, and heat when considering which type of grass seed to apply!
For more information on lawn maintenance, check out our post on spring lawn maintenance!
Where Do I Start?
WOW! That's a lot to consider! The best place to start is take a walk outside. Take pictures of things that seem out of place or unusual. If you’re standing on your lawn and it's feeling a bit "sinking" or spongy this week, a quick trip to our Garden Centre or send us an email so we can help you get the right product for your lawn!
Have you checked your lawn for "sponginess" yet this season?