88 degrees. Should I worry?

I am using using 20 CFLs in a 3x6x6 box. I have a 95CFM exhaust with a can carbon filter attached to it. I am venting through the top of the box into the basement room in which the box is. Intake is 10 inches off the ground in the opposite corner. I know it should be vented out of the room or outside the house but I am already over budget for starting back up from scratch.

I was only running 10 CFL during early veg and the room stayed between 72/77 degrees. Added 10 red spectrum bulbs and the temp shot up to 84/88 degrees.

I plan on venting the heat out or the basement soon. But if I can wait a little bit that would be better. Money is tight and there is still lots of stuff on the list I need for next cycle. So basically I need to figure out where the exhaust lies on the priority list.


It's been a few days now and and the digital thermometer records the low and high. 88 is the high. Which to my knowledge is acceptable but high.

What exactly is the temp range? I am growing Bubba Kush. Not sure how much of a difference the strain makes but I am sure some are more tolerant of high temps.

Any feedback is appreciated.

They're going to start showing some heat stress, so vent the room fast. The highest I've had mine at was 80.

Is that the high, or the average during closed/lights on? If it's the average, than you can run into heat issues. That's not set in stone, though. Some areas where cannabis grows naturally (like the Kush region of Afghanistan, Morocco, and a lot of Southeastern Asia) average 90+ summer, and even early fall, temps. If that's a temp spike, you should investigate, and work to alleviate the issue, before it becomes a problem.

And, for the box, PLEASE tell us, with truth and certainty, that you aren't attempting suicide by putting an CFL array inside cardboard.

if your using co2 then the temps are ok for awhile but try and take a few red lights out they will still bud with out them and run the room at night with cooler temps. you mentioned venting to the basement why not grow there. temps stay cooler and easier to adjust. good luck

The box is in the basement. I meant that the venting goes as far as taking it outside the top of the box. I can feel the heat just standing by the box. The air is not circulating around the basement as it should I am sure. I open the basement doors to the outside every other day. I plan to vent the air outside through a clothes dryer vent just have not done it YET. If the will be ok at 88 degrees for a week to 10 days I can vent to outside then when I have the money. If they are going to fry I will bump it up the priority list and find the money tomorrow.

Lol, no cardboard set up. I am using this.
http://cfl-growlight.com/store/2000-watt-mixed-spectrum-cfl-grow-light-unit-p-19.html

Slightly worried about the "dirty energy" they emit but I usually don't root around in my box too long. Quick inspect, grab a cup of water to test, close it up and go about my day. When I ran HPS I hung out in the room often. Tried out CFL this run due to it being a small box and not a room. Thought heat would be less of an issue with CFL.

Might have answered my own question. Found this.

They are still vegging so maybe it is not so bad till I flower. Which is in about 10 days.

http://www.weed-weeds.com/growing-marijuana22.html

[TABLE="width: 328"]
[TR]
[TD="width: 21, bgcolor: 7F7F7F"][/TD]
[TD="class: smalltext, bgcolor: 7F7F7F"] [h=1]TEMPERATURE[/h] Proper temperature is one highly variable factor. Most books state optimum grow temperature to be 70-80 degrees, but many list extenuating circumstances that allow temperatures to go higher. Assuming genetics is not a factor, marijuana plants seem to be able to absorb more light at higher temps, perhaps up to 90 degrees. High light and CO2 levels could make this go as high as 95 degrees for increased marijuana growth speed.* An optimum of 95 degrees is new data that assumes very-high light, CO2 enrichment of 1500 ppm and good regular venting to keep humidity down. It is not clear if these temperature will reduce potency in flowers. It may be a good idea to reduce temperatures once flowering has started, to preserve potency, even if it does reduce growth speed. But higher temperatures will make plants grow vegetatively much faster, by exciting the plants metabolism, assuming the required levels of CO2 and light are available, and humidity is not allowed to get too high.
With normal levels of CO2, in a well vented space, 90 degrees would seem to be the absolute max, while 85 may be closer to optimum, even with a great deal of light available. Do not let the room temperature get over 35 C (95 F) as this hurts growth. Optimal temperature is 27-30 C (80-86 F) if you have strong light with no CO2 enrichment. Less than 21 C (70 F) is too cold for good growth.
Low temperatures at night are OK down to about 60 degrees outdoors, then start to effect the growth in a big way. Mid 50’s will cause mild shock and 40’s will kill your plants with repeated exposure. Keep your plants warm, especially the roots. Elevate pots if you think the ground is sucking the heat out of the roots. This is an issue if you have a slab or other type of cold floor.
As temperature goes up, so does the ability of the air to hold water, thus reducing humidity, so a higher average temperature should reduce risk of fungus.
Contrary to many reports, high humidity is not good for plants except during germination and rooting. Lower humidity levels help the plant transpire CO2 and reduce risk of molds during flowering.
Studies indicate the potency of buds goes down as the temperature goes up, so it is important to see that the plants do not get too hot during flowering cycles. ? D. Gold: CO2, Temperature and Humidity, 1991 Edited by E. Rosenthal.
[/TD]
[/TR]
[/TABLE]

I would remove some of the bulbs until you can get your venting issue fixed. The heat stress will negate any extra quality that you could get from the extra light.

Also, that article states 95 WITH CO2 enrichment.....high CO2 does tend to change the allowable temperature range. Without it, problems do begin to show up as you reach near 90F.

Take a few bulbs out 20 bulbs is alot for such a small area. You should have like 3 100w cfls or 5 or 6 42w. What is the wattage of each bulb the lower wattage ones seem to produce more heat/light while the higher watt ones run cooler. I have 8, 42w and 2, 65w and temps stay around mid 80s. Also its hotter at the top obviously but i mean 20 bulbs cmon even if there 26w thats alot of space taken up when you could have cut it in half by getting 42w. Post a picture i dont believe you have 20 bulbs thats impossible to comprehend in the area you given not to mention a giant fire hazard and a waste of space.

Dudes!!!$229.00 for a 2000w cfl..........I got y'all for half that and better built.........hahaha!!
Scotty Pot you will be fine for a week or so.Make sure you have good ambient airflow,not direct.Most sativas can take a little heat, with higher heat you want a little higher rh.Put a fan in the basement,and if smell is not an issue..#1 VENT THAT BOX OUTSIDE.GL.peace

I agree..lose the heat.

You will need to pull the air directly up. 20 bulbs in that tight of space is limiting air flow and turning it into an Easy Bake oven.

If it is almost summer in your part of the world, that temp is going to go nowhere but up.

newbie9 said:

Take a few bulbs out 20 bulbs is alot for such a small area. You should have like 3 100w cfls or 5 or 6 42w. What is the wattage of each bulb the lower wattage ones seem to produce more heat/light while the higher watt ones run cooler. I have 8, 42w and 2, 65w and temps stay around mid 80s. Also its hotter at the top obviously but i mean 20 bulbs cmon even if there 26w thats alot of space taken up when you could have cut it in half by getting 42w. Post a picture i dont believe you have 20 bulbs thats impossible to comprehend in the area you given not to mention a giant fire hazard and a waste of space.

Click to expand...

I got you
That's 28 cfl's and 4 23" t5's...........85h/70l........3x3x9ft closet.peace

In my fifteen years of growing there is one thing that holds true no matter what...

Environment,Environment,Environment

You can't beat a dialed environment.It is the number one thing that determines success from failure,poor/mediocre harvests from bumper crops.Next would be genetics.In a dialed environment,with not so great genetics can yield some surprising results,and great genetics in a piss poor environment can/will lead to piss poor results.

IMHO Determining factors/variables in order are

1) Environment
2) Growers skill/experience level
3) Genetics

I added a bigger fan last night. I had a small one blowing across the tops of the plants but I don't think it was moving air around the box. The exhaust works well but I think it was leaving hot spots in the box without a good fan in place inside.

View attachment 2667021

That was the old set up. Lights raised. Crappy little fan to the left only thing pushing the air around.

Added this fan last night.

View attachment 2667028View attachment 2667029

This morning it is at 82 degrees.

I will likely lose a bulb or two. I think losing a little light outweighs the possible damage and potency loss. I believe I have plenty of light. Didn't think I could over do it light wise.


I am running 10 Blue 6500K 26W 1800 Lumen bulbs and 10 Red 2700K 23W 1700 Lumen bulbs. When I bloom here soon I might just drop a few of the blue bulbs.

I also think as i raise the light it will be closer to the exhaust so that may help.

Scotty Pot Seed said:

I am using using 20 CFLs in a 3x6x6 box. I have a 95CFM exhaust with a can carbon filter attached to it. I am venting through the top of the box into the basement room in which the box is. Intake is 10 inches off the ground in the opposite corner. I know it should be vented out of the room or outside the house but I am already over budget for starting back up from scratch.

I was only running 10 CFL during early veg and the room stayed between 72/77 degrees. Added 10 red spectrum bulbs and the temp shot up to 84/88 degrees.

I plan on venting the heat out or the basement soon. But if I can wait a little bit that would be better. Money is tight and there is still lots of stuff on the list I need for next cycle. So basically I need to figure out where the exhaust lies on the priority list.


It's been a few days now and and the digital thermometer records the low and high. 88 is the high. Which to my knowledge is acceptable but high.

What exactly is the temp range? I am growing Bubba Kush. Not sure how much of a difference the strain makes but I am sure some are more tolerant of high temps.

Any feedback is appreciated.

Click to expand...

It really depens on a few things. Yes it is high and yes it could cause a problem, but I have had higher and they survived but it did impact my yeilds. a few degrees lower would be better but it is not always possible.

I would suggest make sure there is airflow over the leaves with a good fan and keep doing what you are doing with venting. as long as there is airflow and the max is not that long each day they will be ok. Try and move your balast, not sure where you have it but that things makes loads of heat, maybe you dont have a hps you mentioned fluros I think. Tired so did not read all the other posts

Good luck buddy.

Its all CFL. I raised them a bit. I was letting them almost touch the tops and had slight issues with leaves curling funny so I raised it about 4/6 inches above the tops. Still plenty of light penetrating. Going to lollypop them soon and put them in the cloner.

Scotty Pot Seed said:

Its all CFL. I raised them a bit. I was letting them almost touch the tops and had slight issues with leaves curling funny so I raised it about 4/6 inches above the tops. Still plenty of light penetrating. Going to lollypop them soon and put them in the cloner.

Click to expand...

Strange that it is so hot with just CFL's in there, you must be in summer. Am I right that it is just very hot in gereral where you are now?

They look good man very impressive for a all CFL setup. If you ever feel the urge to tighter heavier buds HPS is the way to go, maybe just a 250watt to keep the heat down. The spectrum of a HPS is just better for budding. I have done the all the CFL way and could not believe how much more I yielded when swtiching to HPS.

Yea I may switch to a HPS soon just to test it personally. I've used 1000W in a 10x10 room before and had great results. I just know 1000W HPS is going to fry my small box unless I install AC. For now it is a budgeted grow. Starting back up after 10 years. And yes it is starting to get hot here. When I bloom in a week I will run the lights at night. Dropped 2 blue spec bulbs, added a bigger fan and added an oscillating fan to the basement so the hot air isn't just being recycled back into the box. That whole corner the basement had been generally warmer. Temp is stable now at about 75/80 degrees.

Thanks everyone for the help. I tend to panic. Most things I can figure out but its nice to ask someone who has been there. First time in a small box, first time hydro. So I am learning