Here is south Florida..U need to spray Bt BEFORE u start having problems with hornworms. Spray early morning or after sunset. The UV rays from the sun weaken the Bt ingredients. Make sure the leave are DRY before u spray. I check my plants every morning and every night for those horn worms. I'm also lucky..the bluejays LOVE them and will hunt for them on the plants. Spray every 2 weeks regularly and you shouldn't have a problem..or at least not a big problem. U can also use a black light at night to find them..they glow in the dark with the black light.
