Theres a rule of thumb to follow by, when growing marijuana and or even vegetables. It is the last anticipated frost date for your area. Once the threat of frost has gone, everything begins to grow. The frost date varies in different areas, Up here in Canada Where I am, the last frost is approximately may 7. Of course I start plants indoors and move them out about middle of may. Just google frost dates for your area and you will get your answer. Of course, you can start indoors as early as you want, and you can start plants in a greenhouse up to 4 weeks before the last frost because it protects plants from light frosts. But once you find your frost date you will have a good idea on when to plant outside. Hope that helps, happy growing