I would like to ask expieranced growers their opinions on growing marijuana in a 6 x 9 growroom with a pot level temp of 35C---90F under 1000mh RH 50%.How does this heat effect the plants ie health potency,yield diseases etc. I can't get the temp down by passive intake so may have to stay this way as my last grow for awhile.I do have 2 smaller fans blowing on them and a bigger one blowing from a distance to keep the temp at this level.Thanks in advance for your expieriance and help.Showgirl

i have a dehumidifier and an air conditioner, but i dont use either nowadays cos they are very expensive to run. i think your doing all you can SG, we and our outdoor gardens love nice warm summer days, but alas not our indoor grow. i know how to grow perfect pot but cant achieve it with my conditions, so we just do the best we can. the temps will come down in 2 months time.

your temp meter looks like it's in direct light from your lamp? make a cardboard shade to sit a 5 or 6" inches above it, but keeping good air circulation around the thermometer and read the temps again. canna is good up to around 50'c of ambient and radiant heat, but ambient temperature want to be around 28. to much heat can stress them a bit, make sure they always have plenty of water and they should fair ok though, high temps usually makes for airy buds and lower yields,the stomata close up to conserve water and growth slows severely at really high temps.

as above^^.....mornin scraglor n chaps n chappeses..

From what i understand it's ok of your grow room peaks at 30C for a few hours mid day but above 32C and plants stop producing THC. ideal temp 25-28C.

good luck!
Ska

My plants(6 week flower today) are currently at 35c at peak at best part of night it cools down to 31c plants look nice no burned spots or stuff and its full of trichs and buds are smelling great ,only thing i noticed they need more water and food(nutrients) buds will prolly not be fat as it were 24c inside but its summer so better something than nothing i say
humidity around 40% ,cannabis is strong plant it will survive high temp as long it has good fresh air intake-outtake and water
Just my view of the afternoon

How about a cool tube?

I use a clip on 6 inch fan and direct it at the lamp or bulb and it will decrease temps by around 4-6c dependant on how good the fan is, if drastic I use 2 fans pointing at reflector glass, could point it at a bulb should you have no reflector.

Only started using it few weeks back and dropped temps from around 35 to 25c after positioning them just right.

try hanging a wet towel over your intake fan the air blowing in will cool on the wet cloth and may help in lowering the heat a little, i have toyed with lots of ways to lower heat the best way is a cool shade take the heat away befor it builds up in your room

To state the obvious your always going to be looking at high temps with 1000w MH during summer, but as long as the lights are the right distance from the plants, and they don't look like they are burning they should be ok, perhaps less yield and potency overall for each plant as opposed to it being within the temps other people have stated.

Good Luck!

if you inject c02 you can use higher temps (get brewing)

yep get one of these and a fan controller and you,ll never worry again .i have one with a 400w hps and at the mo the extraction is running it half speed and hitting a top temp of 75 degrees .... usually my temps are about 5 degrees above the outside air temps
best grow thing ive ever bought ..... its attached to a five inch fan and filter with a four inch input fan both fans attached to the one controller

works great for me

peppi

stable sativa or that way inclined will do much better in hot room then a dica....id certianly look to work on getting the temps under 30

By how much does using a cool tube effect temperatures?
Have you or anyone else got a comparison?

hi id thought id just throw my 10p worth in. i have a drobe measuring 3ft x 2.5ft and 6 ft high.
im using a 400w hps cooltube. before iwas having temps at 27c with a 250 but as soona s i started with my 400 the temps have hit 35(a cpl weeks ago when the sun was really warm for those cpl weeks) but.....the crop that had 4 weeks to go(i swapped from the 250-400 half way through) thrived!
i had to increase my intakes by twice as much and turn the internally blowing fan up but the chronic loved it!
as long as the temps dont increase anymore you should be fine...as stated before the temps WILL come down in the next few weeks anyways...
good luck with the grow and dont worry too much

withnailed,temp. affected my plants it reduced potency a bit as yield too so get that temps.down next time Herbal

Yield will be down, not a lot, but it will be. Your temps are abit higher than ideal, ideal temp = bigger yield, simple. But not enough to worry about. Potency, wouldn't worry you won't notice.

I wouldn't hang a wet towl over the intake as suggested above, will restrict intake more than cool.

As long as your air is circulating the higher temp won't make that much of a difference.

Air cooled lights will make a big difference. For example a friend had a 2mx2m box with a height of 1m, 2x600w hps air cooled, got a good yield was happy with ( 32o instead of 40 when done in a room with decent height).

I don't think the fan controller is necessary, thats only if she needs to slow it down. With temps like them they need to be running as quick as possible. The cooltube idea is a good one or an active intake if you got the cash.

I think high temps really do affect the yield, my last grow hit 32c most of the time and i noticed my yield was hit quite badly. The herb is perfectly potent though, so i'm not sure if there is any truth in it reducing potency. Afaik sativas actually thrive in higher temps.

All the best with it

Kc

I was having similar problems.
I was using a 400w HPS under a standard reflector in a room 3' x 2' by around 6' high and couldn't get temps lower than 35. I invested in a cool tube (around £50 I think) which lowered the temp to around 30. Worth getting the tube if you can afford it.
Other than that I altered my timmer settings so the light is on when its dark and off durring the hottest part of the day.

Someone did suggest using one of those mini frigdes with the door open and leaving it in the room but haven't tryed it.