Looking for advice for an outdoor greenhouse grow in cold climates.

Tfunk0704 said:

I’d talk to the despenserys out there. My bro works for a very large legal grow and all their plants are outdoor soil. I’d start soon though if your trying to save money by using a greenhouse and sun. At $4 a gram I’m sure plenty of folks around there can tell you when to grow. PS my bro said your only legally allowed to have 2 plants in Oregon, I’m just going by what he said but it might not be a fact. Good luck

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Rec allows 4 plants per household. A med card allows 6 mature plants. Beyond that it's a little tricky depending on zoning, whether or not you're in city limits and the number of cardholders and whether or not there's an adult over 21 without a med card.

steveydvee said:

I do want to aim for a 400-600 square feet greenhouse. And also wouldn't it be more beneficial to use the daylight sun instead of covering it(light dep)? I'm not exactly sure what the benefits of doing light dep besides to speed up the harvest date?

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The most efficient way to heat a greenhouse is by solar heat gain. That's the whole point. Otherwise you might as well just grow indoor.

steveydvee said:

Also I believe that it is 6 plants per medical card holder so possibly doing 12 big boys in the greenhouse. The summer does get pretty hot with highs in the mid 80's.. Do you have any recommendations? Would using a simple wall mount air conditioner be alright?

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An AC would be horribly inefficient for a greenhouse. A proper exhaust with roll up sides and/or a ridge vent are the most common designs. I'm in the Willamette Valley with days that regularly get into the high 90's and usually break into the low 100's. Running my fans on high (5,500cfm) in 12x32 hoophouses with an 8' peak is plenty.

I'm considering using evaporative cooling this summer. You could really benefit from it over on the east side since the air is that much drier. FarmTek has some cheap options for using evaporative cooling misters on greenhouse HAF (horizontal air flow) fans.

Rob Roy said:

If possible always try to get a "two for one" let electricity power a light AND let the light be a heat source too. Not a bad idea to keep a backup heater around too, in case of power failure. Propane heaters are cheap and many don't need electricity.

Consider reading Ed Rosenthal's info. about the varying quality of sunlight at different times of the year re: flowering.

Good luck.

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The best example is running a cogenerator. Basically a gas burning generator that uses a HRV (heat recovery ventilator) and a catalytic converter to scrub the exhaust so you can use it as a heat source and a co2 generator.

SchmoeJoe said:

An AC would be horribly inefficient for a greenhouse. A proper exhaust with roll up sides and/or a ridge vent are the most common designs. I'm in the Willamette Valley with days that regularly get into the high 90's and usually break into the low 100's. Running my fans on high (5,500cfm) in 12x32 hoophouses with an 8' peak is plenty.

I'm considering using evaporative cooling this summer. You could really benefit from it over on the east side since the air is that much drier. FarmTek has some cheap options for using evaporative cooling misters on greenhouse HAF (horizontal air flow) fans.

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Evaporative cooling does seem promising! I definitely have to dial in the humidity to see if this is possible

SchmoeJoe said:

The best example is running a cogenerator. Basically a gas burning generator that uses a HRV (heat recovery ventilator) and a catalytic converter to scrub the exhaust so you can use it as a heat source and a co2 generator.

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Do you happen to have a suggestion on a make/model? I'm unsure where I would go to purchase something like that.

Edit: I'm not sure if this could mean a "wood stove" which seems to be a great way for me to heat it up due to the amount of free lumber I have around my property. If I could scrub the exhaust would the co2 be 100% usable? Next thing I want to do is to poison my plants

The market is so bad. I know several guys with excellent product that can't even get enough $ to cover expenses.

steveydvee said:

Do you happen to have a suggestion on a make/model? I'm unsure where I would go to purchase something like that.

Edit: I'm not sure if this could mean a "wood stove" which seems to be a great way for me to heat it up due to the amount of free lumber I have around my property. If I could scrub the exhaust would the co2 be 100% usable? Next thing I want to do is to poison my plants

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I've only seen a couple of companies selling cogenerator systems. They're usually big custom built rigs that are far enough out of my price range that I haven't looked that far into them.

During the winter, if you're trying to run it year round, your best bet would be to run it sealed with a co2 generator and a dehumidifier. Just let the dehumidifiers exhaust run straight into the greenhouse. Between those two heat sources and the lights you'd have to run you'd be good for heat. That's all assuming you'd be running the inflated double walled style that was mentioned earlier. I've seen one example of a double poly house running up into the mid 80's on a day that stayed well welow freezing in Colorado with no heat sources. You could get similar results in the winter in k falls since it gets a lot of clear weather.

As far as using the evaporative cooling in the summer there's two big things to keep in mind. The summer is mold enough there that you'd only have to use it on the hottest days which will be dry enough that the extra humidity can actually be a good thing. And the plants natural response to excessive heat is to cool itself through transpiration or evaporative cooling. If you do the evaporative cooling for the plants than they can keep there effort focused on growing instead putting most of their effort into cooling themselves.

The passive systems I was talking about are pretty labor intensive to put in place but they are very effective and form a low power use redundancy that makes all of your active systems work that much less.

SchmoeJoe said:

The most efficient way to heat a greenhouse is by solar heat gain. That's the whole point. Otherwise you might as well just grow indoor.

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Agreed. Hard to get any better than sunlight.

Holding some heat during the night then becomes the thing to be solved.

Rob Roy said:

Agreed. Hard to get any better than sunlight.

Holding some heat during the night then becomes the thing to be solved.

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The double poly and no exhaust. The next thing is to run the GAHT system to help regulate the temp a little more and dry the air.

SchmoeJoe said:

The double poly and no exhaust. The next thing is to run the GAHT system to help regulate the temp a little more and dry the air.

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Double poly is a good idea. I've been toying with a similar idea.

Considering putting a smaller greenhouse in the larger greenhouse to use for the late finishers and any other plants (peppers?) that need some extra time. So far it's just a thought, but it keeps reoccurring, so it might become an experiment this fall. If I do, I ought to record the hi and lo temps both inside and out to get a general idea on what / if I'm gaining.

Rob Roy said:

Double poly is a good idea. I've been toying with a similar idea.

Considering putting a smaller greenhouse in the larger greenhouse to use for the late finishers and any other plants (peppers?) that need some extra time. So far it's just a thought, but it keeps reoccurring, so it might become an experiment this fall. If I do, I ought to record the hi and lo temps both inside and out to get a general idea on what / if I'm gaining.

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You can also set up a smaller frame inside of the main greenhouse to dep a set of plants so you can have separate sets of flowering and vegging plants in the same greenhouse.

SchmoeJoe said:

You can also set up a smaller frame inside of the main greenhouse to dep a set of plants so you can have separate sets of flowering and vegging plants in the same greenhouse.

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Good idea. This is where a couple old grow tents might serve as the night time holding area for a few "small" plants in movable containers on wheels.

It takes dedication and a good alarm clock to do the old school light dep thing. A trusted friend who can help out comes in handy too. Everybody needs a break now and then.

Rob Roy said:

Good idea. This is where a couple old grow tents might serve as the night time holding area for a few "small" plants in movable containers on wheels.

It takes dedication and a good alarm clock to do the old school light dep thing. A trusted friend who can help out comes in handy too. Everybody needs a break now and then.

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Oh man, I know.

I didn't read thru the full post so I don't know if this has been mentioned yet...Dig a hole 4-6 feet deep and place the green house in it to take advantage of the geothermal heat. You will still probably need an additional heat source but this will reduce the amount of heat needed.

Ginger Viking said:

I didn't read thru the full post so I don't know if this has been mentioned yet...Dig a hole 4-6 feet deep and place the green house in it to take advantage of the geothermal heat. You will still probably need an additional heat source but this will reduce the amount of heat needed.

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Putting the greenhouse below grade is a great buffer for all seasons.

Ginger Viking said:

I didn't read thru the full post so I don't know if this has been mentioned yet...Dig a hole 4-6 feet deep and place the green house in it to take advantage of the geothermal heat. You will still probably need an additional heat source but this will reduce the amount of heat needed.

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SchmoeJoe said:

Putting the greenhouse below grade is a great buffer for all seasons.

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Small scale, but this was my subterranean solar powered sprout chamber. It got me through some of the late frosts this spring.

I've filled this one in, and it's a pepper pit now. Home of the Hab's and Hab not's.

too larry said:

Small scale, but this was my subterranean solar powered sprout chamber. It got me through some of the late frosts this spring.

View attachment 4151238 I've filled this one in, and it's a pepper pit now. Home of the Hab's and Hab not's.

View attachment 4151243

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That'll do it. Convenient way to repurpose it for the next part of the season too.

SchmoeJoe said:

That'll do it. Convenient way to repurpose it for the next part of the season too.

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It looks like I'm going to get a real greenhouse this year, so I needed to level that area off anyway. I filled in the hole most of the way, then added soil mix. This sand is easy to work with.

I've had a couple of redneck 2x4's and poly greenhouses, but the wife wants one that is not an eyesore. I want to use as many used windows as possible. I also have a good deal of smoked glass from doors. I had thought about using that as the roof, but I'm not sure. I'll have to let my contractor make up my mind.

too larry said:

It looks like I'm going to get a real greenhouse this year, so I needed to level that area off anyway. I filled in the hole most of the way, then added soil mix. This sand is easy to work with.

I've had a couple of redneck 2x4's and poly greenhouses, but the wife wants one that is not an eyesore. I want to use as many used windows as possible. I also have a good deal of smoked glass from doors. I had thought about using that as the roof, but I'm not sure. I'll have to let my contractor make up my mind.

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Look up as much info as you can find about about diy and different commercial designs. Look into the passive systems used in especially hot and cold climates. Once you've read up on enough of the designs and methods out there you'll have a pretty good idea of just what you want.