Light burn from too close, or cause I sprayed them with lights on?

I put these under 400w mh a a week ago and have been lowering the height of the light each day until they start to turn pale green. Yesterday I'd moved it closer because even at 8-12" from the cooltube it was 78-80 on the plants and 75 in the rest of the room. I also misted them as when the light was far away they seemed to like it and there weren't any burns until now.

So today it seems like more have brown on their new shoots, I moved the light away (16"-18") and stopped misting them. Is this from too much light for seedlings, or the misting, or something else like a disease I should be concerned about?



How far do you keep your 1-2 week old seedlings? I had them under a shitty fluorescent and they were stretched. At first they were 3' from the mh, then I lowered it 6" a day. Should I go more like 18-20" away from the tube?

i say 14 inches is about perfect for a cooltube it doesnt look like a light burn to me i mist my plants when i turn my lights on so it can burn off for 12 hours.

Thanks for the specifics. They seem happier when they're misted.

They've been under the mh for a week tomorrow at 16/8. Not sure how big they should be by now. I had them under a really bad fluorescent for several days before moving to the mh. But over the last couple days they seemed back on track. But just today about half a dozen have this brown decay in the same spot on each.

I have a lot of 60 degree air I can pump in and keep them in the 70's even right up on the tube, but since they're so small I think it was counter productive as they started to look sad after a few hours so I backed it off until they get some more roots.

Still keeping it about 75-78 degrees, 45% humidity.

I always mist my plants with the lights on so they will dry and never had a problem. I mist my vegging girls everyday and they seem to love it.I use t5's for vegging so can't talk about the mh light.

Villa said:

I always mist my plants with the lights on so they will dry and never had a problem. I mist my vegging girls everyday and they seem to love it.I use t5's for vegging so can't talk about the mh light.

Click to expand...

DO NOT mist plants during lights on. This will suffocate the plants.

Stomata are not always open, which limits the time frame in which you can apply your nutrients. Most gardeners advise that you spray in the evening time. If growing indoors, the stomata will take about 15-20 minutes to close up after the lights turn off, which gives you time to apply the nutrients without stressing the plants. Outdoors, you can start spraying in the late afternoon when the sun is descending and not directly hitting the plants.

Avoid spraying your plants under full sunlight or bright indoor lights in order to prevent the liquid droplets from magnifying the light source and burning your plants. Also, the stomata are less dilated during the middle of the day in peak heat.

I don't buy the idea that spraying your plants with lights on burns them, I think it's internet "common knowledge" that just gets repeated over and over again. I've never seen it happen personally-have you? Wouldn't all the plants in the Amazon be burned to a crisp at this point? They get sprayed by water then exposed to equatorial sun over and over again. I know a lot of people say to spray your plants just after lights off...but I wouldn't do that. If you want to spray them when it's dark, I'd do it like 20 min before lights on...you don't want your plants sitting in a tent all night wet. You want those babies to dry off with a quickness.