Sarah I live in the Atlantic northeast and grow SA bulbs successfully in my basement using LED lights. Equivalent to say a 600-1000 watt HID light. In the greenhouse you only need supplemental lighting. The greenhouses at Rutgers University use 400 watt high pressure sodium lights. That covers a 4' x 4' area. Duration is trial and error. Start with 4 hours. 8-10 am and 2-4 pm. Based on your growth add hours as needed. Ken P Old Bridge, NJ Zone 6 b