Merit Insecticide Granules can only be applied with a spreader and then watered in with rainfall or irrigation. If you want to use Merit in a pump sprayer you can use the liquid concentrate version which is Merit 2F Insecticide.
Merit Insecticide Granules is not labeled to be used on edibles. The active ingredient to too high a percantage to be safe for human consumption. It would be highly recommended to discard anything it was applied to and remove the soil and replace with new as ithe product can last in the soil for some time.
We recommend contacting your local cooperative extension office to ask about exact 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.
Merit Granules are a great choice for grubs, just be sure you are applying before egg hatch so that the active ingredient has time to work systemically. There are some spreaders listed on the product label, however yours is not one of them. We usually recommend starting around one setting below the middle setting and then adjusting as needed.
For your more general pest prevention, Talstar Xtra Granules would be a great choice.
Merit 0.5 G Insecticide is labeled for use around flowers at a rate of 1.4 – 1.8 lbs per 1000 sq ft. Since this is just an insecticide, then it typically does not cause issues around flowers. If the granules were watered in very heavily, then that could encourage disease development around ornamental plants, but otherwise you may need to speak to a master gardener for assistance with any issues concerning your flowers.
Timing for applications of Merit 0.5 G Insecticide Granules will depend on the target pest being treated.
We recommend contacting your Local Cooperative Extension Office for advice on the best time to apply insecticides for pests in your region as they are a great resource when dealing with pests and most have a master gardener and an entomologist on staff to answer questions.