Merit 75 as a Drench

[DebsC]

Big guns time. I'm sick and tired of scale showing up over and over on some plants. It's time to get rid of the little buggers!

I grow in lava rock mixed with charcoal.

Is pouring Merit through the medium one time going to be enough or do you put the pot in a bucket or other container and pour the mixture through again?

How much mixture do you pour on each pot?

This process is repeated how often?

Anybody know of any orchids that are sensitive to Merit? Like, it might damage them?

Any info and help is much appreciated!