How Much Heat Fluctuation Can A Plant Stand?

SWIM is setting up a shed grow, but as winter is kicking in, he is using a heater, timed for 15minutes every hour to keep the potential plants warm.

The tempeture is fluctuating from about 11C to 25C.
Is this going to be OK for plants, or will they just die from heat stress?

Any help would be much appreciated with this, I have Googled but with no relevant info, only that they get too hot, they die, get too cold, they die etc... etc... Nothing on the fluctuations.

I get that certain strains will handle it better some not, FYI SWIM intends to grow WhiteRhino.

Cheers in advance.

magicianhumphrey said:

SWIM is setting up a shed grow, but as winter is kicking in, he is using a heater, timed for 15minutes every hour to keep the potential plants warm.

The tempeture is fluctuating from about 11C to 25C.
Is this going to be OK for plants, or will they just die from heat stress?

Any help would be much appreciated with this, I have Googled but with no relevant info, only that they get too hot, they die, get too cold, they die etc... etc... Nothing on the fluctuations.

I get that certain strains will handle it better some not, FYI SWIM intends to grow WhiteRhino.

Cheers in advance.

Click to expand...

In nature, wide temperature swings are possible, but rare. You could have a hot summer day and have a cold front roll thru with thunderstorms dropping temps by 10-20 degrees easily. The bigger picture here is what temps are normal based on your location and time of year. If the temps get hot in the day, it usually drops at night and you want to mimic these conditions with your lighting as well.

Try not to go over 78 degrees F (75 ideal)during the day if possible and not to dip below 60 at night or lights off. Too hot and the stomates on the leaves close up sending the plant into self defense mode (no growth). Too cold at night and plant metabolism slows down too much. There may be some plants that can stand temps outside of these ranges, but at what cost? When flowering, cooler nights are to be expected as fall is setting in, and the plants know this. Vegging plants like warm temps and fairly high humidity to encourage that 'jungle like growth' Hot too hot or humid tho or mold moves in.

I'm sure they're are others here who can chime in on what works for them, but these are the guidelines I grow by with great results! Good luck!

idk the celsius conversion but if you run your room at 80 degrees faranheit u dont want them to go lower the thirty degress during lights off.. if this does happen a simple space heater on a timer will help

Hi,

Thanks for those tips, very much appreciated.

I kinda get from that if the temp drops to about 15C in the night and upto about 25C in the day, then unless the strain is overly sensitive it should be OK.

Problem SWIM has got is that if it is going between 15C - 25C constantly, ie fan goes on 15minutes every hour, raises temp to 25C and slowly cools to 15C then fan comes on again, is this going to work?

SWIM needs a digital themostat heater I know, it would be a lot bloody easier! (just short of cash at the mo)

Cheers.

I've got a similar problem - growing during the winter in an outdoor shed. What I'm doing is running a space heater through a programmable outlet thermostat:

http://www.amazon.com/WIN100-Heating-Cooling-Programmable-Thermostat/dp/B000E7NYY8/ref=pd_bxgy_hi_img_c

http://lux-thermostat.blogspot.com/2009/11/win100n-heating-cooling-programmable.html
this will give me a more exacting temp control than the ordinary space heater dials. They're about 35 bucks

I can set the thermo to an exact temp in which to come on, and shut off. I figure that during the light cycle, my 250w HID will keep ample heat in the shed. During the night cycles, the space heater will keep the area around the plant warmed to whatever temp I choose.

archaeo said:

I've got a similar problem - growing during the winter in an outdoor shed. What I'm doing is running a space heater through a programmable outlet thermostat:

http://www.amazon.com/WIN100-Heating-Cooling-Programmable-Thermostat/dp/B000E7NYY8/ref=pd_bxgy_hi_img_c


this will give me a more exacting temp control than the ordinary space heater dials. They're about 35 bucks

I can set the thermo to an exact temp in which to come on, and shut off. I figure that during the light cycle, my 250w HID will keep ample heat in the shed. During the night cycles, the space heater will keep the area around the plant warmed to whatever temp I choose.

Click to expand...

Cheers, that's mint cause SWIM has got a few fairly decent heaters... Gotta try find a UK version now.

I used a manual / analogue type heater a few winters ago and all was fine for a few weeks, then one day I walked in to my old growroom, to find it boiling hot, I was like 'shit, shit shit' for some reason Themostat had failed and cooked 3 plants, subsequently all 3 died within 3-4 days, freaking tragedy. No one needs that.

On a similar note around the same time I had to do some modding to my outdoor grow area, so I put 3 plants outdoors in the snow, hmm yeah I know stupid right?, I just thought they'd be OK for like 20 mins or so. But nope all 3 died also within about a week.

Plants do seem to have this shock 'barrier' and when you cross it you're screwed... Just wondering if anyone has anymore accurate info about this?

DUDE!- Just found UK version of that device: http://www.amazon.co.uk/Thermostat-Tubular-Heater-Heating-Control/dp/B001AE2PEO/ref=sr_1_1?ie=UTF8&qid=1258324584&sr=8-1-spell

Thanks, you're a star!