Heating The Greenhouse? 50 Degrees F Too Low?

  • Thread starter KarmaPharmer
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KarmaPharmer

KarmaPharmer

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Hey all,

So I am currently fighting cold temps and tons of rain. It sucks.

My humidity is staying 60-80 percent even with an industrial dehumidifer running. I am keeping a close eye on budrot but have lost a couple nugs here and there.

But my big question for the experienced out there is this - how actively are the plants growing when it is just 50 degrees? I have read that photosynthesis really starts to stall around 40-50 F

I have another 2 weeks of buds really starting to fatten

50 is about what the greenhouse is getting to on cold days, I still have to heat at night when it dips into freezing. With a propane heater it takes about a dollar or at most $2 an hour to heat this thing ~10 degrees F above outside temps.

So with that in mind I am wondering if I am going to majorly regret just running the heater at night and letting my buds ripen in 50 F, or if biting that 30$ a day propane bill is worth it to have my ladies sitting comfortably in the mid 60s.
 
Jack og

Jack og

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Hmm. Depending on strain, some actually do better in lower temps.
Kush or indica dominant like the lower temp.
Some hybrids actually make nice colors at t lower temps.
So , try to keep her from freezing and let her finish off.
I’m putting in a radiant heater in my greenhouse.
One Takagi, 6-8gpm tankless propane heater with 2 manifold system.
Gonna run copper the length and width off the house with radiators at termination, with a single pump to recirculate the hot water at 167f max those boilers will run.
Tests show for my 120sqft greenhouse, one 10gal tank will run 30-40 days at $3.49 a gal. That’s cheap. 8 solar panels run the electrical side of things. Fans and led lights as supplement.
 
MidwestToker

MidwestToker

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Really depends on what your root zone temps are getting to at night. That's where my problems came in when I was growing in a cool environment.
 
G gnome

G gnome

20,448
638
Hmm. Depending on strain, some actually do better in lower temps.
Kush or indica dominant like the lower temp.
Some hybrids actually make nice colors at t lower temps.
So , try to keep her from freezing and let her finish off.
I’m putting in a radiant heater in my greenhouse.
One Takagi, 6-8gpm tankless propane heater with 2 manifold system.
Gonna run copper the length and width off the house with radiators at termination, with a single pump to recirculate the hot water at 167f max those boilers will run.
Tests show for my 120sqft greenhouse, one 10gal tank will run 30-40 days at $3.49 a gal. That’s cheap. 8 solar panels run the electrical side of things. Fans and led lights as supplement.
3.49 a gallon? Ur getting ass raped!!! Haha. I just bought propane for 1.50
 
OldSmokie76

OldSmokie76

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Really depends on what your root zone temps are getting to at night. That's where my problems came in when I was growing in a cool environment.
Rootzone temps? @MidwestToker Any suggestions? I'm assuming above 60 and below 80 are best range depending on grow media. Any input or experience?
 
KarmaPharmer

KarmaPharmer

23
3
Hmm. Depending on strain, some actually do better in lower temps.
Kush or indica dominant like the lower temp.
Some hybrids actually make nice colors at t lower temps.
So , try to keep her from freezing and let her finish off.
I’m putting in a radiant heater in my greenhouse.
One Takagi, 6-8gpm tankless propane heater with 2 manifold system.
Gonna run copper the length and width off the house with radiators at termination, with a single pump to recirculate the hot water at 167f max those boilers will run.
Tests show for my 120sqft greenhouse, one 10gal tank will run 30-40 days at $3.49 a gal. That’s cheap. 8 solar panels run the electrical side of things. Fans and led lights as supplement.

Yeah they dont seem to mind the cold, no burnt hairs or leaf tips yet, but some of these have 2 or 3 weeks left and they just are not as fat as I am used to seeing buds get by now. Was not sure if it is the cold, or the old ass greenhouse poly material not letting in enough light. Definitely getting my purple strains to turn beautiful purple, but even the non purple are getting some nice shades to em, so hey there is a bright side to this weather i guess :nailbiting:

Right on jack, that is a good deal! I cant wait to build my own set up again.

I recently moved to a city so there was no back yard growing for me this year. Instead I found a few folks with nice property who let me use their space, but holy shit would I have built that thing differently. I honestly dont know how the PVC and greenhouse poly has stood up for the last couple years for them.
 
MidwestToker

MidwestToker

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Rootzone temps? @MidwestToker Any suggestions? I'm assuming above 60 and below 80 are best range depending on grow media. Any input or experience?
Anything below 60 and you'll see a drastic reduction of growth and as far as getting colors that can be accomplished with nutrient modifications.
DSCN0706
 
KarmaPharmer

KarmaPharmer

23
3
Very pretty.

Yeah I am definitely not TRYING to get colors on this bud, I really dont mind nice light green nugs, I just want lots of them.
So if I have a couple dozen small (4 foot, carefully trained so each probably 6ish equally main stems a piece) and they still have the last 2-3 weeks do you think its worth while yield wise to crank the heat and keep it 60+ during the days and 40s at night?

Or am I better off saving my self from spending that ~30$ a day + inconvenience of refilling my tanks twice a week?

Its really hard to decide for me since of course I dont wanna dump any more cash than necessary into this grow, but I usually find the last 2-3 weeks is where the buds really put on that weight...and I definitely dont wanna stunt that.
 
KarmaPharmer

KarmaPharmer

23
3
Anything below 60 and you'll see a drastic reduction of growth and as far as getting colors that can be accomplished with nutrient modifications.
View attachment 836626


Toker, thats some gorgeous nug, are you saying you turned that plant that dark through nutrient deprevation/overload? I thought that purpling was almost entirely accomplished through temp drops, whats your method?
 
Jimster

Jimster

Supporter
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Things are certainly going to slow down a lot when you drop the temp into the lower 50s, but it shouldn't hurt anything. I've kept a few going thru minor frosts and they were the only remaining green thing outdoors, and they turned out pretty nice with more flavor than most. If you can keep the roots warm, it will help a good bit to keep them more active. As long as they don't freeze at night, I wouldn't worry too much abut them and concentrate on keeping them warmer during the day.
 
MidwestToker

MidwestToker

1,228
263
Yes, through nutrient depletion. It's the same that happens in the wild, either the soil is depleted of nutrients from the plants consuming it all or the root zone temps drop enough for the microbes to slow or stop being active enough to brake down the elements for use as nutrition to the plant.
DSCN0757
DSCN0759
 
KarmaPharmer

KarmaPharmer

23
3
Right on, my purples are looking really pretty but those would probably do that at any temp below 70.
Other plants are acheiving a nice purple hue on the leaves though, a gelato cross I have is looking gorgeous in its fade to purple right now. It is one of the few ones I was trying synthetic nutes on, the rest are veganic soils. I have not started flushing my synthetic pots yet so I assume all the change in color is temp dependent and a product of the plant naturally maturing

@Jimster Thanks, I decided to do what I need to for keeping frost off my gals at night, but Ill be running the heater day side for the next couple weeks to maintain 60+ on the colder days. This should help them finish strong, and should also help fight the cold-thriving molds

or at least I sure hope so when it is going to cost 30$ a day to run
 
Jimster

Jimster

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My setup is all indoors and pretty well insulated, but I like when it gets below zero F and I have things finishing...the cold that DOES get thru gives everything a nice color. I guess there are ways to influence the color changes with nutrients, but I like the long cold nights for bringing out the best flavors. It seems, at least to me, that the cold keeps some of the more volatile flavors in greater concentrations. Could be my imagination.
 

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