I’m going to grow 3 autofem plants in a greenhouse but I read that during veg they need about 18-24 hours of constant light, while where I live we only get about 12 hours of direct sunlight. I’m fine with buying supplemental lighting, but was wondering what type? I think HPS/MH would be too hot for my climate, so I was thinking T5 or LEDs. But, how strong should the lights be? Will it effect the plants if they go from direct sunlight to only supplemental light at night?
No T5s. No HPS/MH. Do yourself a favor and buy a quantum light board. Here's a link to a thread I am part of concerning alternative HLG lighting. I got worse probs then temps atm; the ole 'not enough lime in the promix' trick. I had added... I don't see me using any other artificial lighting since I got these boards.
If your just looking to keep them in veg some daylight spectrum l.e.d. bulbs from walmart will do it without making them stretch or anything weird. I have used them successfully for years to keep my plants vegging all spring and early summer. The plant can only process so many hours of sunlight a day anyways so as long as the plant is under a bright light of any kind for a few hours after sun down it will remain in veg. Some people will say oh well you have to have this kind of growlight or that kind. When in fact anything in the cool white to daylight spectrum works as long as your getting more than 8-10 hrs of actual sunlight a day. MJane