I've used it on the soil, but I wouldnt say "as a drench." When the spray didn't do the trick, I resorted to watering the pot with the solution. I figured it would kill anything in the pot too. The last couple of years, I have covered the top of the pot's soil with coffee grounds. I'm not swearing that it has been effective, but I only found one brug with spider mites. We've had a lot of rain this spring. The mites just may be waiting for me to turn my back!
And welcome to NGA!
