The most Popular brand of Bt for worms is Dipel (dust) or Thuricide (liquid) I have used house brands just as effective. Don't use neem oil, but if the concentrations are same should be no problem. There are species of Bt designed for other pests like potato beetles, but it is quite rare.
Concur with Rita on Miracle Gro. half strength is about as high as you want to go.
