Is it a good idea to put my 400w 8 inches from my seedlings?

Glad the subject caught your attention, because i'm assuming most would be screaming "no!". However,i just added a 6" inch high powered exhaust fan, plus a humidifier with a fan RIGHT next to the plants, and the plant temperature seems totally fine for the seedlings. I have a thermostat in the rockwool that reads 74 degrees, so i imagine the leaves are maybe 78 to 80. I planted the seeds on the 9th of may, so they're 12 days old, and are still pretty small.

If the temperature seems okay, should i conitinue, or sohuld I change something? Thanks.

seems ok, but watch em close!

Okay, so one seedling may be as close as 6 inches.... As long as the temperature is good, then i'm okay? Then why does everyone else have so many temperature problems??

well if its cool enough go for it. check this out

no cool tubes small spaces ect...

Dude, that chart is amazing, thanks. I think my temp is fine considering i have this huge empty closet (16 sq feet) and only a 400w, and a fan, and a HUUUUUUUUGE exhaust ( at least it sounds huge lol).

sickstoner said:

well if its cool enough go for it. check this out

Click to expand...

I just realized that chart was for a sodium and i've got a MH light, are they roughly the same?

ahh here you go

Great, well i'm going to bed and will be up in like 4-5 hours, so i'll have a gander in the morning and see if there's any signs of stress, and if not i'll continue. You guys have been amazing, thanks.

sickstoner said:

ahh here you go

Click to expand...

Heat isn't the only issue you have to think about. Contrary to popular belief it IS possible to give plants too much light, or actually i should say that it's possible to have the light intensity too high, which will create all the symptoms of heat stress even if though the temperature itself isn't too high. Young seedlings and clones are particularly vulnerable because they don't have much in the way of a root system. The intensity of the light will cause the plants to start shedding moisture through the leaves even if the temp is not very high, and the more intense the light the faster the water is lost. Problem is, young plants roots aren't developed enough to replace the water as fast as the light is sucking it out, and it won't take long for the leaves to start drying out and curling up.

Personally, I don't put plants under my 400w until they are at least 5" tall and have spent at least a week in their final pot under a bank of T8's to develop roots. Even then I put them on the outside edge of the lights coverage area for the first 4-5 days, and only move them directly under the light once they are closing in on 12" and have a well developed root system.

Temps ok or not. Thats too much light for seedlings. I would back it off to at least 18 inches and let them grow too the light.

get some t5's save lots of money on electric costs

Way to much light.......... If you are working with rooted clones thats a different story, but 8" is still a little close........... I used to try and get the lights as close as possible, now I look for a balance of footprint and light concentration, increasing my overall yield.

cool, i moved the light up 3 inches... By the way, I was referring the distance between the lights and the canopy, to clarify