I'm going to say June.
March is too early, because you can still get frost until the first of May, and frost will kill your plants.
You can plant after May 1st, but June is better because if your plants get out too early they will grow HUGE and be hard to hide.
Also you want to wait until the trees and bushes have a lot of leaves on them for hiding your plants.
stinkyattic Reviewed by stinkyattic on . growing i am growing a plant for the first time next summer im from pennsylvania and i was wondering when it would b e a good time to plant outdoors in pa.. Rating: 5