420 Magazine Background

How much light for fresh seedlings?


New Member
Hey guys, i have freshly sprouted sage seeds in rockwool cubes 4 days old. i have a 200 watt cfl about 18" above, just wondering how close it should be to the seedlings, should i lower it to just a few inches above the plants or give them more time? assuming heat is not an issue. Any thoughts would be apreciated, thanks


Plant of the Month Winner - December 2011
Good question.

I would say lower it some. If heat is not an issue go for 8"-12" for a few days and see how she responds. By responds I mean as far as stretching goes. If the light is too far the seedling will grow lanky with a weak stalk due to it stretching toward the light. Better to start off a little higher and gradually lower it as the plant grows more fan leaves over the next couple of weeks. Ideally you want it as close as you can get it with cfl's.

Always hold your hand, palm down, under the light right above the top of the plant. Hold it there for a minute. If it's too hot for your hand after that minute the light is too close.

Hope this helps. Good luck with your seedlings!


New Member
Also being that the seedlings are in rockwool cubes and not soil
Should I feed them with a super weak nute solution, the leaves
Look a little pale? It is day 10 and it sound early to fertilize but I
Feel like they are lacking what they would normally get out of seedling
Starter potting soil?

Captain Kronic

Member of the Month: July 2011
Did you PH the Rock first?
RockWool cubes are not PH'd, so if you didn't pre-soak them in PH'd water, you may have a really really high PH... that is more than enough to make your babies perform badly and have more probs even!
Some peeps use a really weak nute solution for their seedling/sprouts, I don't but, I know that you can use a flowering formula, they like the Phosphorous... helps them establish roots faster/better!
Personally, I just get them started in the cubes, then, just as soon as they are up and running, I throw them in the soil so I don't loose any root growth when roots come out the bottom of the cubes... I like it better, I don't fancy life in the cubes for my babies... that's just me though!
I am unclear if you are going to be using soil but, if you don't decide to give them any nutes yet... just put them in some fresh Organic soil... I like Happy Frog or Ocean Forrest... HP being my fav!


New Member
definitely go to 8" to avoid stretch. i used 150 cfl and was able to get 4-6" with no problem. I NEVER feed anything other than ph'd water till after the 3rd true leaf
Top Bottom