Dealing with heat issues in the desert...

[Rusty Trichome]

Below is what I do for my soil grow during our hot summer months in the southwestern desert. I have never grown hydro, so am unable to verify any of this for anything other than soil grows.
My flowershed is an outdoor shed approx 8' x 12' x 8' tall, of which a quarter if it is for growing. (no, it's not a metal shed)

In my humble (sometimes) opinion, "must keep temps below 80" is a guideline, especially appropriate for beginners.
-However-
Being anal about it is truly unnecessary. Ambient temps inside my outdoor growshed (2 x 400w HPS's) often reach the low 100's. This is including having the window A/C unit on 'high'.
Does it slow the growth...? Yes, a tad. Delays harvest about a week or so. However the yield is there and the quality is there.

First technique I learned
...quit hanging the thermometer by the canopy top. Was too depressing and stressful. All of my temps listed are ambient room temp, taken from the side of the grow, about 5' off the ground. I use the 'back of the hand' method of determining canopy temps. If it's not too hot for me after a minute or so, they'll be fine. (change hands often when doing this, or go around with one hand tanned, one hand not tanned)

Window A/C units.
When using a crappy window unit A/C, and it's real hot...open a vent or window, just a crack. (the higher the vent, the better) Trapped, heated air doesn't cool very well.

Never overfeed when hot.
...don't feed full-strength nutes all at once. Split it up into a couple of 'light' feedings equaling the same nute intake per week as recommended by manufacturer. Example...Instead of giving once-weekly nutes at 2 tsp per gallon, give 2 feedings at 1 tsp per gallon. (I give mine on mondays and thursdays) On the other days, I add either plain ph'd water, or micronutes, per my schedule. (Fox Farms) The strongest additive I put in the potting soil prior to use is worm castings and michorrizae fungi. I steer-clear of manures. (not so during the winter months)

Never spray with the lights on. Each drop of water sitting on the leaf acts just like a magnifying glass, and it will burn the leaf tissue. Flowering ladies prefer the lower humidity anyway. Spraying will also increase possibility of mold. You'd be amazed how long a drop of water can remain sandwiched between two leaves. Be careful watering on hot-muggy days, as it will increase your humidity levels, which can also increase chances of mold.

Ditch the intake fans unless it's hooked-up to an A/c unit.
You can add all the intake fans you want to add, and they will never work like having a strong exhaust, placed high to remove nothing but the hot air and cannabis scent. The suction caused by having the exhaust on, pulls-in the exact same quantity of air that's going out. (physics - nature abhors a vaccuum)

Stagnant air traps heat and provides no fresh oxygen or CO2.
I usually have two dedicated 'oscillating budfans' which I keep on 24/7. One on either corner of the front of the grow. Both are pointing at a slight up-angle, but one is only for the space between lamp and canopy, the other blows 'thru' the plants, providing fresh air to soil, and removing any stagnant heat. Obstructions (unnecessary shit in the room) can and will trap heat.

Lamps and plexiglass.
I don't have a cool tube set-up, but when it's just too hot at canopy top, I do hang a 3/8" plexiglass sheet horizontally above the ladies, (just below the lights) to block the direct heat from the lamp.
If nothing else works to keep the temps within 110, I break-down and raise the lights a bit. If it's still over 115, I'll shut the HID's off, and turn on some 23w CFL'S (soft white) to keep the light schedule on target. I don't know if this is a benefit, but it makes me feel better.

This is all I can think of right now, but if y'all have any questions...fell free ask.

Rusty Trichome Reviewed by Rusty Trichome on 07-27-2008. Dealing with heat issues in the desert... Below is what I do for my soil grow during our hot summer months in the southwestern desert. I have never grown hydro, so am unable to verify any of this for anything other than soil grows. My flowershed is an outdoor shed approx 8' x 12' x 8' tall, of which a quarter if it is for growing. (no, it's not a metal shed) In my humble (sometimes) opinion, "must keep temps below 80" is a guideline, especially appropriate for beginners. -However- Being anal about it is truly unnecessary. Rating: 5

[Rusty Trichome]

If you want to get my attention, I'd prefer that you start your own thread. :thumbsup:

[likekind]

ay rusty i hate to keep bugging you but if you could i need a little help i posted some pics of my little guys, for the most part they seem ok how ever two of them are getting these purple spotting under there leaves(not mold) and their stems are purple i was told it was a cal mag problem but i started giving them the cal mag but i dont know if its working. also my plants are only a week and a half old and they are super dank(whole room is lit up) is that normal for such young plants? well any ways if you could take a look at them and let me know it would be apriciated http://boards.cannabis.com/growing-i...-new-pics.html

[Rusty Trichome]

Hot conditions aren't the optimal, but they're doable. Just try not to let the temps get out of hand, and keep an eye on 'em. :thumbsup:

[CanGroIt]

HAHA!!!! Like such a noooooB, I was worried about 90 degrees..... I'll be like the tenth or twentieth person to say it, Thank you Rusty for posting this. Glad you did!!!! Now I can sleep better tonight:thumbsup:......

CanGroIt::::::

[stjr2k]

I'd like to jump on the "Thank you Rusty" wagon! If you grow outdoors where I live, your crop will see high temps 95+ and high humidity for two full months or longer. I never had any problems from it. But, when my temps went to 90 in my closet, I started scrambling like I was trying to avoid the apocalypse. LOL Thanks again!

[likekind]

ay thanks for the help on my post i left some pics of my grow room and the specs on it . if you have a chance to check it out i would be greatfull

[should]

Thanks for the thread rusty, ill have to try some of those techniques... its sad looking at the thermometer and seeing high 90s

[lunarose]

Rusty,

I have the same problem this time of year in my greenhouse. I have been reading about smartpots and think I'll probably give them a try next year since they are suppose to help keep the roots cooler.

Another tactic that has worked for me is to cut a piece of that weed blocker fabric with a hole in the middle for your plant and then cover it with a layer of straight perlite.

[Rusty Trichome]

Thanks for the thread rusty, ill have to try some of those techniques... its sad looking at the thermometer and seeing high 90s

My pleasure.
Keep in mind, I do not recommend anyone purposely raise the temps in their growroom to these extremes. These are methods to help keep temps reasonable enough to get quality results from a very harsh enviornment. :thumbsup:

Rusty,
I have the same problem this time of year in my greenhouse. I have been reading about smartpots and think I'll probably give them a try next year since they are suppose to help keep the roots cooler..

Would put some more thought into the SmartPots. Thoughts like...how does the pot cool the water, or at the very least, not retain ambient heat? The water will act like an insulator, collecting external heat. Or at the very least, not let the heat escape. Also, cannabis doesn't much like being fed from the bottom. At least mine didn't. (no fresh water to upper root zones, and conditions that virtually guarantee root rot in the lower root zones)

Another tactic that has worked for me is to cut a piece of that weed blocker fabric with a hole in the middle for your plant and then cover it with a layer of straight perlite.

I'm a bit doubtful the cloth and perlite are necessary, but...If it works, stick with it. A fan blowing across the pots will circulate air and should cool the roots just fine. (unless your greenhouse is sitting in the middle of an asphalt parking lot, lol)