Question:
I am making my first attemt to start seeds using grow lights. How high above the seedlings should I place the lights?
I recently researched lights. If you’re using LEDs or full-spectrum fluorescents you can keep the bulbs close. If you’re using HID lights (like metal halide or similar) or any other lights that put off heat, you’ll need to keep them at least 8-10 inches away from the tips. More distance if the wattage is high. Maybe think of 1.5 to 2 inches per 100 watts of HID bulb.
I have some T-8 fluorescents over my lettuce and heat isn’t an issue.
Not far...a couple of inches (3-4") at most...too high, and you will wind up with leggy seedlings. Adjust light upward as seedlings grow.
Close as possible without touching or scorching. It depends on your lights. The newer high output lights don’t get very hot, so you can get really close. Adjust the height as they grow.
“I am making my first attemt to start seeds using grow lights. How high above the seedlings should I place the lights?”
Put the grow lamp as close to the top of the cup or pot as you can get it - the more heat the seeds get, the better they like it. As the plants grow, keep the light just above the plants - if you place it high above the plants, they will reach for the light and you will have long spindly, lousy, plants.