Grow Tent: High Temp, Low Humidity Problem

Hey guys, I planted 6 seeds 4 days ago in rockwool cubes and yesterday 5 of them had germinated and a little stem about 1 inch has sprouted up. So I turned on my 200W CFL lights yesterday and had to set my temperature to about 95 degrees Fahrenheit as my 6" 240 CFM exhaust fan kept sucking the humidity out of my 4'x4' grow tent in lower temperatures. Woke up this morning, the temperature next to the plants are 95-97 degrees and the humidity is at about 27-30% humidity. But the last seed had germinated and now has a little stem of about 0.5 inch, and 4 have developed their first set of green leaves, while one still has its seed shell at the tip of the growth. I know the optimal range should be around 80-85 degrees with 40-70% humidity and was wondering if this would stunt my plants development.


The CFLs are about 12-16 inches away from the seedlings

I do not have a fan speed controller for the 6" 240 CFM fan, should I get one? EDIT: When the fans are on it feels my tent is being sucked out the top with visible pressure making the tent seem to suck inwards.

I heard for higher temps, low humidity a co2 system works great, should I make a DIY drip system for co2?

So far, it seems like everything is working out fine with the last seed germinated and the cotyledons coming out, was wondering if it will be a problem once more leaves develop. No visible signs of lights burn, except it was the cubes were a little dry even though I watered them last night when I turned on the CFL

imo: put ur plants in a damp plastic bag until at least 4 inches tall with glass of water

open to breathe at least 4-6 times per day

try and get ur temp down to 77F otherwize growth will stall

later raise humidity to 60% with a damp towel or dish of water

cfl's at 2-3 inches of top most leaf is better

good luck

ps no need for fans or 200w yet just use 2 cfl's 1x at 6500k and the other at 2700k

I was just in a similar situation. get an "ultrasonic cool mist vaporizer" humidifier with an adjustable output dial. they're cheap, I got a 1 gallon unit at Walmart for 28 dollars. it was pretty easy to dial in the humidity , and filling it with cold water will bring the temp down

vostok said:

imo: put ur plants in a damp plastic bag until at least 4 inches tall with glass of water

open to breathe at least 4-6 times per day

try and get ur temp down to 77F otherwize growth will stall

later raise humidity to 60% with a damp towel or dish of water

cfl's at 2-3 inches of top most leaf is better

good luck

ps no need for fans or 200w yet just use 2 cfl's 1x at 6500k and the other at 2700k

Click to expand...

I have a humidity dome I used while germinating the seeds, I was just reading that lights should be put on the seedling once the little stem (hypocotyl) that they should be placed under a light. Should I remove some bulbs and make it 100W and put the humidity dome back up?

Royalroacho said:

I was just in a similar situation. get an "ultrasonic cool mist vaporizer" humidifier with an adjustable output dial. they're cheap, I got a 1 gallon unit at Walmart for 28 dollars. it was pretty easy to dial in the humidity , and filling it with cold water will bring the temp down

Click to expand...

Will definitely go pick up a humidifier, I had no idea they were that cheap, holy shit

Yeah, I'm really happy I picked that up, It fixed both my temp and humidity issue. I needed to use it in tandem with a fan controller to balance things out. I don't know where you get supplies, but try to read reviews, some of the controls cause the fans to vibrate on lower settings

A little update, now the temp is at around 85-88 degrees in the humidity dome with 45-55% humidity. I've noticed that on all of the plants that the top of the stem are turning purple, and was wondering if this was normal?

I had that problem too. the best answer I could find was that it's caused by overwatering inducing phosphorous/magnesium deficiency, or genetics. I'm pretty sure mine were a little too wet. They're also a purple strain though. Alot of people say its normal they turn out fine as they grow, but I couldn't find any pics of their grows. I don't know how normal mine are anyway. the dark devil autos I'm growing came out of their seeds upside down, and one is trifoliate...