I have 27 watt 1300 lumens standard screw in full-spectrum bulbs. How far from new seedlings should these bulbs be placed? 4" above or more? How about when plants reach 6" in height? I planned on 2 bulbs per 4' wide area on stainless steel shelving. Please advise. Thanks Linda Barclay
If these are standard house incandescent bulbs, then I would not recommend using these. Most of their energy is put off as heat, instead of light quality.
Now, if these are CFL (the corkscrew looking type) then these can be fine for seedlings. LED's have the same effectiveness as long as you get the kind that don't have a globe filtering light. These can safely be hung 6 inches to a foot from the top of the plants at any time. Some may be able to handle being closer, but I would be wary of burning.