Winter Greenhouse Heating Ideas

[RomanW]

So, I'm planning on adding a greenhouse to the end of my garage (It would be south facing) and am trying to think up ideas over the winter and plan out how to make this greenhouse able to still produce during winter. Problem is, it gets -20 here on average for at least 4-5 months so just relying on the Sun to keep it warm, isn't going to work. If at all possible, I'd like it to sustain itself. I have a friend who used to write program for automation in the Oil patch, and he suggested a couple of things as well, which I am intrigued about.

1. Solar glycol heating on the roof, utilizing a solar powered pump, and temp regulation either through fluid flow control, or greenhouse vent control with a Rasp Pi, Arduino, etc.

2. Solar heating and circulation through convection using copper tubing (Like what some people do with fires, tubing, and a hottub) Also controlled like #1.

3. Running ducting from the garage into the GH, and utilizing the garage furnace. (Yes, this defeats the off grid desire, but since the furnace wouldn't be dedicated to heating only this space, it seems easier to justify lol)

I'm not sure what would be more effective for actually eating the space (Running hot fluid through a radiator and blowing that around, or insulating under the floor from outside and using in floor heating) yet. But as for actually heating the fluid, I saw a video of someone getting their hose water to get to about 75 deg C just by coiling 50' and painting it black.

The other consideration is weather protection. It hails up here sometimes, and that could ruin the pipes. I wonder if making a solar box for the pipes and using lexan, or something of the like that could stand up to a little bit of abuse would work well? having that box may also help since I have dark shingles. Not only would the black pipes soak in the sun, but the shingles would add extra heat because of the box on top of them?

Anyways, I'm sure I've forgotten something, but fire away!

 

[peakbagger]

Conventional solar hot water is limited to about a 80F temperature rise over the ambient temperature, Evacuated tubes are somewhat more efficient at temperature rise but far more expensive.

 

[RomanW]

These puppies?

 

[ABMax24]

IMO conventional greenhouses loose far to much heat in our climate to be practical for winter use.

In terms of energy use you are going to be better off to build a well insulated greenhouse without windows and use LED grow lights. The grow lights will use far less energy than whatever heating method you use to compensate for the greenhouse windows.

Solar heating doesn't work well in our climate in winter either.

I've got a few friends that grow "stuff" in their basements. They use the popup grow tents with LED grow lights and automated ventilation with humidity control vented out a window. All stuff easily bought online.

Our local Co-op grocery store has a mini greenhouse in a seacan, same deal, spray foam the inside and grow lights for the plants.

High intensity hydroponics seem to be the commerical greenhouses of the future.

 

[Dan Freeman]

I did this a few years back, but I dismantled it after two winters. It just took up too much greenhouse space with those 4-55 gallon drums and hanging solar collectors. It worked quite well, and I was able to grow all winter with the use of grow lights, too. If I did it like this again, I would have gone with a glycol system to get the solar collectors out of the greenhouse, or (ideally) buy a quality 4-season greenhouse that would be so much easier to keep heated in the winter. I only use my greenhouse in the spring, summer, and fall now. I grow in my house in the winter and use the greenhouse to store extra firewood.

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[RomanW]

IMO conventional greenhouses loose far to much heat in our climate to be practical for winter use.

In terms of energy use you are going to be better off to build a well insulated greenhouse without windows and use LED grow lights. The grow lights will use far less energy than whatever heating method you use to compensate for the greenhouse windows.

Solar heating doesn't work well in our climate in winter either.

I've got a few friends that grow "stuff" in their basements. They use the popup grow tents with LED grow lights and automated ventilation with humidity control vented out a window. All stuff easily bought online.

Our local Co-op grocery store has a mini greenhouse in a seacan, same deal, spray foam the inside and grow lights for the plants.

High intensity hydroponics seem to be the commerical greenhouses of the future.

Good points. Especially since I know what winter is like up in your neck of the woods. I could just power the LED's and automation with solar as well...

 

[RomanW]

I did this a few years back, but I dismantled it after two winters. It just took up too much greenhouse space with those 4-55 gallon drums and hanging solar collectors. It worked quite well, and I was able to grow all winter with the use of grow lights, too. If I did it like this again, I would have gone with a glycol system to get the solar collectors out of the greenhouse, or (ideally) buy a quality 4-season greenhouse that would be so much easier to keep heated in the winter. I only use my greenhouse in the spring, summer, and fall now. I grow in my house in the winter and use the greenhouse to store extra firewood.

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No kidding. I'm surprised you didn't run collectors outside of the GH...

 

[Dan Freeman]

No kidding. I'm surprised you didn't run collectors outside of the GH...

I was doing it on the cheap at the time and didn't want to pay the extra that would be needed for a glycol system. My greenhouse is not a 4-season greenhouse. Most greenhouses aren't, even though they may be marketed as such. The only decent 4 season greenhouses I have found, if you are not going to build it yourself, are the ones from https://ceresgs.com/ and https://growingspaces.com/

 

[MikeK]

So, I'm planning on adding a greenhouse to the end of my garage (It would be south facing) and am trying to think up ideas over the winter and plan out how to make this greenhouse able to still produce during winter. Problem is, it gets -20 here on average for at least 4-5 months so just relying on the Sun to keep it warm, isn't going to work. If at all possible, I'd like it to sustain itself. I have a friend who used to write program for automation in the Oil patch, and he suggested a couple of things as well, which I am intrigued about.

1. Solar glycol heating on the roof, utilizing a solar powered pump, and temp regulation either through fluid flow control, or greenhouse vent control with a Rasp Pi, Arduino, etc.

2. Solar heating and circulation through convection using copper tubing (Like what some people do with fires, tubing, and a hottub) Also controlled like #1.

3. Running ducting from the garage into the GH, and utilizing the garage furnace. (Yes, this defeats the off grid desire, but since the furnace wouldn't be dedicated to heating only this space, it seems easier to justify lol)

I'm not sure what would be more effective for actually eating the space (Running hot fluid through a radiator and blowing that around, or insulating under the floor from outside and using in floor heating) yet. But as for actually heating the fluid, I saw a video of someone getting their hose water to get to about 75 deg C just by coiling 50' and painting it black.

The other consideration is weather protection. It hails up here sometimes, and that could ruin the pipes. I wonder if making a solar box for the pipes and using lexan, or something of the like that could stand up to a little bit of abuse would work well? having that box may also help since I have dark shingles. Not only would the black pipes soak in the sun, but the shingles would add extra heat because of the box on top of them?

Anyways, I'm sure I've forgotten something, but fire away!

It sounds like you are thinking about doing something like in this book:

Amazon product ASIN 0615297242
To my recollection they talk about growing more cool season crops with minimal heat supplementation to keep things above freezing. They aren't growing tomatoes in winter in MN. They/We are quite a bit south of you but certainly it is still cold in winter and even if you can't grow things all year this would be a lot of season extension.

 

[MikeK]

It sounds like you are thinking about doing something like in this book:

Amazon product ASIN 0615297242
To my recollection they talk about growing more cool season crops with minimal heat supplementation to keep things above freezing. They aren't growing tomatoes in winter in MN. They/We are quite a bit south of you but certainly it is still cold in winter and even if you can't grow things all year this would be a lot of season extension.

Also found this youtube video by author

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[RomanW]

Awesome thank you!

 

[EbS-P]

Any good references for the costs and ROI times? For personal greenhouses.

 

[Dan Freeman]

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Also, check out their website at https://ceresgs.com/environmental-controls/gaht/

Not cheap to do, but worth it.

Also check out: https://ceresgs.com/shop/

 

[RomanW]

Any good references for the costs and ROI times? For personal greenhouses.

I was thinking the same thing. To build my own for even just 3 seasons is going to be an easy $2000

 

[Dan Freeman]

Any good references for the costs and ROI times? For personal greenhouses.

If you are building a greenhouse because you are growing food to sell to support yourself, then look at ROI.

If you are building a greenhouse as a way to grow your food for yourself and your family, forget the ROI. Just think of the many other advantages.
Fresh nutrition, better than you can buy
A hobby
A source of therapy
...just to name a few

I am looking to put up a new greenhouse within the coming year to replace my old one, a first-timer greenhouse. This new one is going to cost me in the neighborhood of $15,000-$16,000 when finished and the ROI is the last thing on my mind. This one will have a pond and a recreation (relaxation) area. (Perhaps I'm just at that age?) A greenhouse is a way of life, not an enclosed environment to grow some food cheaply.

JMHO

 

[Poindexter]

I agree with ABMax that if you are committing to year round growing a sealed unit with LED lighting may be a better choice. And Dan Freeman's comments re goal clarification are spot on.

On my suburban lot in a similar climate we do have some raised beds for quick crops like salad greens, but for long growing season plants like tomato and pepper we start them in the dining room in front of the south facing bay window, move them outdoors still potted for the summer, and then bring them back indoors to finish.

One crop we have tried to maximize is raspberry, practically a weed up here - but loaded with healthy nutrients and very expensive to buy in the grocery store. The fruit freezes well, the plants overwinter outdoors with minimal maintenance, and the fertilizer needs are fairly minimal. I am looking at starting a blueberry patch, but blueberry are plentiful on nearby public lands.

I am opposed to attached greenhouses - mostly because of all the effort I have tied up in managing the dampness in my wall cavities.

 

[Poindexter]

I was thinking the same thing. To build my own for even just 3 seasons is going to be an easy $2000

You might consider building an insulated raised bed, that is insulate the walls and floor. But small, maybe 2 feet wide by 8 feet long or so. On mine I used short pieces of 1" PVC pipe (maybe a foot long) attached to the inside walls with pipe strapping, then 10 foot sections of 3/4 inch PVC bent gently to make hoops (like a conestoga wagon) and then plastic sheeting over that.

My goal was to keep the soil bacteria alive over the winter in mine, it didn't work. But you are south of Edmonton, so maybe.

You should get a ton of hits if you internet search on " hoop house", I am just thinking of a small inexpensive one.

 

[RomanW]

If you are building a greenhouse because you are growing food to sell to support yourself, then look at ROI.

If you are building a greenhouse as a way to grow your food for yourself and your family, forget the ROI. Just think of the many other advantages.
Fresh nutrition, better than you can buy
A hobby
A source of therapy
...just to name a few

Oh I totally agree. I think for me ROI, is more how long it will take to equal out cost to build compared to savings on food prices by growing my own. But that will be a question I just need to sit down and figure out. And it may take a couple of years, because to truly know how that's going to work out, I have to see what and how much I can produce in it, and factor how much I've saved by growing those things in the greenhouse.

I'm not balking at the idea, it was more just curiosity for me.

I'm going to have a green house regardless. Lol.

I just need to decide whether to build or buy.

I agree with ABMax that if you are committing to year round growing a sealed unit with LED lighting may be a better choice. And Dan Freeman's comments re goal clarification are spot on.

On my suburban lot in a similar climate we do have some raised beds for quick crops like salad greens, but for long growing season plants like tomato and pepper we start them in the dining room in front of the south facing bay window, move them outdoors still potted for the summer, and then bring them back indoors to finish.

One crop we have tried to maximize is raspberry, practically a weed up here - but loaded with healthy nutrients and very expensive to buy in the grocery store. The fruit freezes well, the plants overwinter outdoors with minimal maintenance, and the fertilizer needs are fairly minimal. I am looking at starting a blueberry patch, but blueberry are plentiful on nearby public lands.

I am opposed to attached greenhouses - mostly because of all the effort I have tied up in managing the dampness in my wall cavities.

I've gone away from the attached idea. Sounds like more trouble than its worth. Raspberries are a weed here too, I have a bunch of wild ones kicking around the property which is cool. So I wont even incorporate those into my FF. I hate trying to control those things lol.

My plan is to do something similar to you and grow some greens inside the house over winter. We have a lot of west facing windows and get a lot of light in the house throughout the day, so we may only need to supplement a little with UV lamps in the winter just to get us past the 4pm-10pm time when it gets dark.

 

[RomanW]

@Dan Freeman My wife and I are thinking of going with this. It may not be a 4 season... but I think with some creative heating ideas, we may be able to add a month or so to each end of our growing season...

10 ft Wide Traditional Greenhouse (Size: 10 ft x 13 ft)

abgreenhousebuilders.com

 

[EbS-P]

With a couple grow lights one can grow a lot of lettuce in 12 sq ft on 3 or 4 levels. I see a green house as a growing season extension tool. Yes you can get 4 season ones sure but now you are really committed to keeping it warm. Down here we have the opposite problem we would have to keep it cool in the summer (probably easier).

@Dan Freeman My wife and I are thinking of going with this. It may not be a 4 season... but I think with some creative heating ideas, we may be able to add a month or so to each end of our growing season...

10 ft Wide Traditional Greenhouse (Size: 10 ft x 13 ft)

abgreenhousebuilders.com

I had to look up the Beaufort scale. I think it hits a good price point and strength for wind and snow. That extra month. Is just so weather dependent. I wonder what one of the DIY mini splits could do in a greenhouse?

 

[RomanW]

I wonder what one of the DIY mini splits could do in a greenhouse?

I've never heard of these, what are they?

 

[EbS-P]

I've never heard of these, what are they?

Heatpump Mr cool DIY is the brand. I’m not sure it’s really well suited to extreme cold but it could help manage humidity too. Really I was just wanting something automatic. I could get a unit for 1500$ US

120volt 20 amp.

Heating a just to extend a month each way probably isn’t to difficult but. I’m not familiar with your climate swings. My guess is spring could be more difficult than fall. But starting everything inside for a a couple weeks is easy enough.

 

[peakbagger]

I recently saw solar panels made specifically for greenhouses. They let the light in and generate power. I woudl be tempted to try to use them as a roof. (broken link removed to https://www.ebay.com/itm/285062372153?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20220705100511%26meid%3D50edb0475741411d814b23e7708a3269%26pid%3D101524%26rk%3D1%26rkt%3D1%26itm%3D285062372153%26pmt%3D0%26noa%3D1%26pg%3D2380057%26algv%3DRecentlyViewedItemsV2%26brand%3DSolar&_trksid=p2380057.c101524.m146925&_trkparms=pageci%3Ab84191d8-9678-11ed-95d8-da28f25c38ab%7Cparentrq%3Ac045c0b31850a74489de4be1ffff9924%7Ciid%3A1)

Structurally they should be fine. the biggest issue is sealing the seams. I am not aware of a commercially rated system but plenty of folks are trying to homebrew methods.

If the new air to water heat pumps were readily available, it would be tempting to use one to heat up thermal storage during the day and then let it radiate out into the greenhouse overnight. I know folks with seasonal green houses that use 55 gallon drums of water to stretch the season in the late winter into fall in northern NH. They have some overwintering cold crops and also can start seedlings 60 days earlier in the spring plus can plant late season crops that carry them into mid December.

 

[EbS-P]

I recently saw solar panels made specifically for greenhouses. They let the light in and generate power. I woudl be tempted to try to use them as a roof. (broken link removed to https://www.ebay.com/itm/285062372153?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D20220705100511%26meid%3D50edb0475741411d814b23e7708a3269%26pid%3D101524%26rk%3D1%26rkt%3D1%26itm%3D285062372153%26pmt%3D0%26noa%3D1%26pg%3D2380057%26algv%3DRecentlyViewedItemsV2%26brand%3DSolar&_trksid=p2380057.c101524.m146925&_trkparms=pageci%3Ab84191d8-9678-11ed-95d8-da28f25c38ab%7Cparentrq%3Ac045c0b31850a74489de4be1ffff9924%7Ciid%3A1)

Structurally they should be fine. the biggest issue is sealing the seams. I am not aware of a commercially rated system but plenty of folks are trying to homebrew methods.

If the new air to water heat pumps were readily available, it would be tempting to use one to heat up thermal storage during the day and then let it radiate out into the greenhouse overnight. I know folks with seasonal green houses that use 55 gallon drums of water to stretch the season in the late winter into fall in northern NH. They have some overwintering cold crops and also can start seedlings 60 days earlier in the spring plus can plant late season crops that carry them into mid December.

I like that idea of the green house solar panels. Even an air to air heat pump . Coupled with some buried perf pipe and a blower could be a good system. Would need some math on the thermal storage capacity. To get it adequate.

 

[peakbagger]

I think the trick would be to run glycol under the soil instead of heating the air in the greenhouse.