I would like to know from today(april 10) is ok to apply nematodes for the lawn in Markham?


Thank you for your question.

Nematodes are commonly used to control white grubs in lawns.  The best time to apply them is in spring and in late August.   They require a soil temperatures of 15 degrees C or greater to be effective.  They infect grubs within 2 days of application and kill them within 14 days.  Nematodes will not kill the entire grub population in your lawn, but will reduce it drastically.

Over the past week, the GTA has had significant rainfall and even snow in some areas.  Most soils are saturated with water.  Saturated soils are slower to warm up.  I would recommend waiting a couple of weeks to allow time for the excess moisture to drain away and the soil to warm up.

If you have already purchased your nematodes, keep them refrigerated until ready to use. Be sure to follow the instructions on the package in particular to water before and after the application as the nematodes need moisture to make their way into the soil.  It is also best to apply them on an overcast day or in the early evening to help keep the nematodes from drying out.  Nematodes can also be applied late August/early September and you may need a second application if you have a significant grub infestation. Note that as your grub problem recedes so will the nematode population as their food source is dwindling.

Another alternative is to keep a healthy and thick lawn, by feeding it with top soil and seeding in the early spring. Also avoid cutting your lawn too short during the summer months and water deeply once a week.

Lastly, if the battle is too much, you may want to consider using lawn alternatives for your yard. See the following Garden guide by the Toronto Master Gardeners in collaboration with the City of Toronto:

Good luck in your battle against the grubs!