Seedlings under 400W MH , question

[speedyp]

soo it's my first time growing with HID. I have a combo MH/HPS. My seedlings are 4 days old.

I read the general rule for MH light is about 12" away from the plants. This is what I'm doing right now but I'm a little scared that they are getting too much heat at this early stage.

I also hear if my light is too far away the plants will stretch so I am a little conflicted and not sure what to do.

Should I keep the light at 12" or should the light be further away for those young seedlings ?

 

[OrganicTreees]

put your hand right above the top of the plant, hold it there for about a minute, if it's uncomfortable, you should back the light off a little bit, otherwise it will be fine. I keep a fan blowing on my bulb, and it allows me to keep the light around 6-8" from the top of my plants without too much heat. the further away the light is from the plant, the less lumens the plant will get, so closer is always better as long as you have the heat under control

 

[speedyp]

Alright so the same basic rule applies even when they are real young. I was not sure If I needed to be more careful at the seedling stage.

 

[OrganicTreees]

you do to an extent, but the same rules apply. Give it a couple of weeks and they will be exploding with new growth

 

[Kush Killer]

I wondered same thing, I have mine about 12" away and temp is @ 78.2 lights on 68.4 lights of. I have my first set of true leaves and 2nd set is makin their apperance. I'm. 10days in from seed germination

 

[Dayzt]

Easy solution to this.... don't use the HID light until you've grown past the 'seedling' stage. Those little plants will either stretch trying to reach the light, or fry from it being too close... Always start your seedlings with small CFL lights (those spiraly ones - get a mixture of cool and warm ones), that way you can get as close as a few inches away from them so they stay nice and short from the get-go, and aren't stressed from any unnecessary heat issues. Keep a small fan blowing across the top of them as well at that stage - just enough to keep them moving slightly, and as they get stronger, give them a bit more wind...

It's all about 'gradually' introducing them to more light, more heat and more movement. All of these things build it them to withstand the larger and stronger environment they're destined for... Peace!!

 

[Kush Killer]

Mine were under cfl I just switched to MH on Sunday, when I seen my set 2nd set of true leaves formingnot having a prob. With stretch or with heat as I stated ealier

 

[speedyp]

I am using an MH from the start. I was not aware a CFL is better at first. I have a fan going and blowing air between the light and the plants and another one to bring air into the room. Can I get away with this or are my plants in danger ?

 

[Dayzt]

You'll probably be fine in the long run, but remember that 'less is more' - try to start out light with seedlings, in all elements (light, nutrient, heat, etc..) The less stress the better when they're just starting. They won't use as much light at your MH is providing at that point yet anyway - it's worth investing in some small CFL lighting for seedling plants for that reason.