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My "new" little indoor greenhouse has 6 biax 40 watt bulbs (18900 lumen output). Should I be concerned/careful about moving plants from the east windowsill to this new light? Any thoughts on how long the lights should stay on? Should I start with a shorter time (say 8 hours) and gradually build up (to say, 12 hours)? (I'm completely new to growing under lights!) Thanks!
I'm assuming those are T12 fluorescents. If so, you generally don't have to worry about the switch causing burning. If the light is significantly brighter, you may notice some reddish color developing int the leaves. This depends on the plant, and I generally don't worry about it. With T12 you need to have the bulbs fairly close to the plants-12 inches or less. Lights, not matter the type should be left on 12-16 hours a day as a general rule.
Susan
Julie I agree with Susan. What burns plants is heat build up at the leaf surface. One can easily do that moving a plant from under a fluorescent into a sunny window but the reverse is not true
Thanks, Susan and Ron, for the super helpful info, which all makes sense to me. Yes, they are T12 bulbs and the greenhouse is so small the plants will never be more than 8-9" from ALL six the bulbs. I moved several plants into the little greenhouse yesterday... will need to jury-rig some adjustable shelves to fit more! Did I say more orchids? :-)
I am curious about you mini greenhouse....could you post some pictures.
I'd love to see it as I am interested in a mini greenhouse myself. :)
Thanks.
Danie
If you are worried about burning your plants, feel the leaves if they are hot you can move them farther from the lights or set a little muffin fan or two over the tops of the plants which will cool them and prevent sunburn. I grow with T5 HO lights which can give 5000fc of light. I set the shelves lower than I would if I was using T12's or T8's. This accommodates the lower light orchids. I set those that require higher light on overturned plastic shoe boxes which brings the plants closer to the lights. Good luck Pat
I usually put mine 6 to 4 inches away from the light and they seem to do ok. there is no point on placing your plants 1ft or farther from the light because most of the light will be lost at this distance and you will be wasting your time. The closer the better and if the lights get too hot or something just have a fan blowing some air on them and that will help.