They can be hard to control. Get rid of all hiding places fo them and hoe up the first inch or so of soil, if you haven't mulched. I know there are "dusts" out there specifically for them. I think dipel works, but I am not sure if it is organic etc... I think the dusts are specialized to just hit those worms, but I don't know how organic you are and/or all the organic rules... I do organic as much as possible ( I garden for my family)....but, I did have to use dipel last year just for them or I'd have had nothing left. Collars work pretty good, but they'd have been impractical for me, I had way too many plants to collar all of them. Diatomaceous earth might work too... I hope others can give more info... good luck!