Grow lights

How long do you leave your grow lights each day when propagating seeds?

I usually leave mine on for 16-17 hours.

thanks

Usually 16 hours. For seeds "requiring light for germination" e.g., impatiens, I left them on for 20 hours.

One more question, please . . . when you use a grow/shop light, can a dome also be used? If so, how far from the top of the dome should the light be?

Thank you for your assistance!

Syrumani,
I used a regular shop light hanging from the ceiling in my utility wash room.
Then, I made a wooden rack to put the seed trays on.
The rack held three 72 plug seed trays.
Of course the light was not directly over all of the seeds, but I kept rotating them, and moving them around for equal light.

to your question, before the seedlings sprouted, I had the dome on the trays, and the top of the dome was barely touching the shop light frame. so the actual light tubes were at least 3" from the soil. After the seeds sprouted, I kept the domes off during the day, under the lights. Lights on for at least 16 hours. As the seeds grew, I lowed the wooden rack by chain so that the tubes were still at least 3" from the tops of the plants.

By keeping the tubes close to the plants, this causes the youg plants to bush out, and produce more leaves. If you kept the tubes too hight, the young plants will grow too tall, reaching for the light. Too tall, and they'll just flop over.

Hope that helps.

If you've got one of those tall domes, it's pretty much impossible to have the lights close enough to the seedlings. Personally, I always start weaning the seedlings off the dome once they germinate anyway--it helps with air circulation, preventing fungal growth, etc.

Thanks for the help. Right now, the light is about 4" over the top of the dome, so I guess I can lower it a bit. It is one of the small domes, although I do have a tall dome with valves for humidity control to use later.