Ed from Smis, Ca writes
Grubs Away Insecticide is most effective when grass is actively growing so that it is absorbed through the roots. When grass is dormant it would not absorb and translocate the product throughout. Depending on your location and the pest your are trying to treat for, application of Grubs Away can be anytime between mid May and mid August. We recommend contacting your local cooperative extension office to ask about insecticide timing for the pests in your region. These offices are an invaluable resource when dealing with pests and most have a master gardener and an entomologist on staff to answer pest insect questions.
Answer last updated on: 10/11/2016