Based on what I could find: 1/4 Tsp will treat 50ft² which is equal to 1,250,000 Nematodes. So that's prolly more than enough for three plants. I've never used em before though so someone else with more experience might know more accurate info.
The irony of using nematodes is that you have to keep the soil moist for a couple of weeks, making the conditions for gnat population growth better, before a total crash and burn.
Triple Threat Benefi. nemo Treats alot way more than that I treat plots with it.Can tell you where to get them.Just know how to use them and when..Ground has to be at temp.. Thanks Bama