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How To Heat Greenhouse In Winter Without Electricity

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Have a small greenhouse or larger greenhouses that do not have power and wondering if you can heat greenhouse in winter without electricity?

Plants growing in greenhouse in winter

Even if you live in an area that experiences little or no snowfall, chances are good that at one time or another, you’ve had to scrape your driveway, sidewalk, parking lot, or any other hard-surfaced area that might be covered with ice and/or snow.

If you want to harness the power of nature and heat your greenhouse even when the weather outside is cold and snowy, but don’t have power to it, you’re going to need to know how to heat a greenhouse in winter without electricity.

I am about to reveal the most unknown (yet very simple) ways to heat a greenhouse in the winter… and… it doesn’t require any electricity!

These methods were used by the early farmers and are still being used by many greenhouses today including mine.

There are many benefits to growing your plants inside a greenhouse. For one thing, it allows you to grow plants in the winter when you can no longer grow in a normal garden.

Secondly, it helps the plants grow faster because they are not restricted by the cold air.

So anyway, let’s say you have a greenhouse and it gets really cold winter temperatures outside. What is your first instinct?

Many people wonder if it’s possible to heat a greenhouse during the winter months without using any electricity so they can extend the growing season.

The good news, it’s very possible. Here are six easy-to-do steps you can take to get your greenhouse up and growing before the last frost date.

Winterizing To Heat Greenhouse:

As soon as the temperature drops, there are certain things you need to think about doing to your greenhouse that will prep it for the long, cold winter ahead and cut down on the heat loss.

Some of these items include cleaning the structure of the house, caulking any gaps or cracks, and adding insulation.

It is a good idea to check all the joints and seams where the different pieces of your greenhouse meet each other. If they aren’t sealed tightly, then it is likely that there is a fair amount of air leakage.

Sealing these joints and seams is very important. You don’t want any drafts coming into or out of your greenhouse.

A draft is basically what causes the temperature in your greenhouse to fall. It is caused by the escape of cooled or warm air from one area to another.

When this happens, the temperature inside your greenhouse will be as low as the outside temperature.

As you may have noticed depending on where your greenhouse is, most if not all of the sunlight comes in on the south side in the winter.

That means all the other sides can be insulated to help hold in the heat longer. But how do you insulate a greenhouse?

Insulation comes in many different forms. You can use bubble wrap, plastic sheeting, cardboard, or styrofoam.

The best way I have found is to use is plastic cardboard because it holds much heat like cardboard but does not absorb moisture.

Whatever you use should be thick and not placed on the south-facing sides.

Black water jugs behind strawberry plants in a greenhouse

Heat Greenhouse With Water:

Did you know you can use water to heat a greenhouse? This is a common way to add a little heat. This is done by filling black jugs or black water barrels, or black tubing full of water.

They need to be black as black absorbs the heat from the sun in the day. That heats up the water and then at night as the water slowly cools he releases that heat into the greenhouse.

It is not a lot of heat that is released but enough to keep the greenhouse above freezing when temps dip down to around the freezing mark.

Other than only working when temps are right around the freezing mark outside, the other downside to this method does not work well if the greenhouse does not get much sunlight.

If there is no sunlight they can not absorb the solar energy and the water will not get heated.

Also, if you live in an area that has hard winters and the temperature drops way below zero a lot this will not be enough to keep the greenhouse heated.

Black plastic tote compost bin in greenhouse under plant bench

Compost Heating:

Adding a compost bin to the greenhouse is another great way to add a little heat to the greenhouse.

The heat generated from the decomposition process increases the temperature of the compost itself, which in turn radiates warmth and slightly raises the greenhouse temperature.

You can use just about anything as a compost bin. Just make sure it has a few holes in it to allow air in. 

You also need to make sure that the compost is packed tightly or it will not decompose as well and in turn, not put off as much heat.

I like to use a small black (I use black so it helps it heat up in the day from the sun) plastic tote in the bottom of my greenhouse packed full of things you can compost.

If you have a larger greenhouse, you could also just have a large compost pile inside the greenhouse.

Candle Heating:

Depending on the size of your greenhouse, you can add a little heat with a simple candle. You just have to make sure to be safe and have it so that nothing touches the flam. The last thing you need is a fire in the greenhouse.

While just a candle adds a little heat, the best way to use is to heat a pot with it. So that it also holds the heat for a little while.

You can do that by placing small candles such as tea lights in a glass or fire-safe dish. You can use a wire roaster rack in the center then place clay or ceramic pots over it so that it is upside down over the candles.

Make sure you use a pot that has a hole in the bottom.

Thermal Mass Heating:

Thermal mass is the property of a substance that remains warm after it has absorbed heat. This property is important in a greenhouse because it helps retain heat for a long period of time and maintain a steady temperature.

A good way to use thermal mass in a greenhouse as a form of heat is to install some large stones. Place on them beneath the growing beds.

Stones absorb thermal energy and retain heat better than concrete. They will remain warm for a much longer period of time. If you want to step it up, you can also paint the rocks black to help speed up the heating when the sun comes out.

Another option would be to have large black containers full of soil. Or even a container of soil that is also covered by clear plastic or glass so that it helps absorb the heat of the sun and then retains that heat to release at night.

Ash bucket on ground in center of greenhouse

Heating With Hot Ashes:

Ok, so while I use most if not all the options I have talked about so far to heat my small greenhouse garden this is the method that is hands down my best greenhouse heater on those really cold nights.

Take a metal bucket and put hot ashes in the bucket and place it on the ground in the middle of the greenhouse. The most important thing to remember is you have to MAKE SURE there is nothing around it that could start a fire as the bucket will be hot.

We have a wood stove that we burn in the winter. So it doubles as cleaning out the stove and heating the greenhouse at the same time.

However, if you don’t have a wood stove, you can take the ashes from a fire pit or barrel for your greenhouse heating too.

This will put off a considerable amount of heat for hours and then slowly cool. Depending on your area and the temperatures, you can put it in the greenhouse at night.

For me, I find having the other methods above will hold it above freezing in the greenhouse (when the temperatures dip in the ’20s degrees Fahrenheit outside) until the early morning hours such as about 5 am.

So because I am an early riser anyway, I just take the bucket out and put it in the greenhouse at around 5 am.

Using The Earth To Heat:

You can use the earth to heat greenhouses but this method only works best when you have a large greenhouse.

There are two different ways to use the earth to keep the temperature of your greenhouse above freezing. The first is to sink the entire greenhouse into the ground.

Dig in the ground so that at least the bottom half part of the greenhouse is below ground level by a few feet. With this, you get the best results the deeper or the more of the greenhouse is below the ground.

The other idea is to dig down and place some PVC pipe underground below the first like. You want the PVC to be in a long U shape. Kinda like the top of a football goal.

That way the bottom part is underground and being heated by the earth’s temperatures. Then that heat will rise out the open ends and heat the greenhouse.

Conclusion:

In conclusion, a greenhouse can provide year-round fresh food even in cooler temperatures. It also provides a safe haven for tender plants and flowers that would otherwise die in the winter weather.

We have shared several ideas on how to have a winter greenhouse and heat the greenhouse in winter without electricity.

Ash bucket in greenhouse with text overlay at top that says How To Heat Greenhouse In Winter Without Electricity

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Comments

  1. Cori says

    It is also possible to heat a greenhouse by keeping animals inside; such as rabbits.

    I have raised rabbits for years, primary for their pellets, which are among the finest plant foods available naturally.

    Rabbits do fine in cold weather, but I plan to have a few in cages inside the greenhouses, during our coldest months, which should both help keep the rabbits more comfortable, as well as closer to their food sources; and will keep the plants happier, as in addition to warmth, the plants will benefit from the increased carbon dioxide from the rabbits’ exhalations.

    Reply

    • Reuse Grow Enjoy says

      Yes, you can use animals to help heat the greenhouse. Just be sure that on those warm days it does not get too hot in the greenhouse for the pets.

      Reply

      • Dina says

        I read that Chickens don’t do well in the greenhouse…during the week around the full moon- the moon shining through is amplified and this can harm the chickens well being.

        Reply

        • Reuse Grow Enjoy says

          You could always move them to a coop for that week if your chickens look to be acting off. Or you can put a doghouse style coop in the greenhouse depending on the size. That way the heat will still be in the greenhouse but they will be in a place that is dark.

          Reply

  2. Maria M. says

    The amount of ads throughout the article, sides of the article at the bottom of the article were unbearable. I had to close it out. Sorry

    Reply

  5. Peter R. says

    Thank you, for all these wonderful heating tips.
    Any thoughts, on, using decomposed cat waste, as fertilizer…

    Reply

  7. Rich T. says

    Dear RGE, I live in North Central Colorado at 7500 ft. Last summer while my wife and I were isolating due to “the Co-co”, I assembled my Harbor Freight 10×12 greenhouse. The instructions required the base be dug into the ground for stability, so I figured that if I’m digging that far down I might as well put in provisions for “in-floor” heat. So I laid out cattle mesh and zip-tied 100’ of 3/4” Wirsbo “Hepex” and then covered it with garden cloth (bringing up my tails in each front corner on either side of the door opening.
    I then placed 10” of 3/4 gravel over the tubing, and 2” hexagonal pavers on top of the compacted gravel. I then fabricated a solar panel of 4” single wall flue pipe and 4-5’ sections of copper fin tube from hydronic baseboards. (I work in the HVAC industry so all of the parts and equipment mentioned is readily available to me).
    For a heat sink I used a 65 gallon electric water heater tank from a replacement job.( tank was ok, no leaks).
    I piped the Thermosiphon system according to a schematic I found on Pinterest. With properly placed fittings, valves and thermometers, monitoring and control of the free heat provided by the sun makes for a toasty warm greenhouse in the winter. The liquid in my system is a 50/50 mix of water and propylene glycol.Freezing point is around 30degrees below zero Fahrenheit. I also installed foam board between the studs on the north wall and covered the entire framing (installed wood framing inside for structural support during high winds) with 10 mil clear visqueen plastic. At this point I feel that everything has been done to harvest and retain solar heat to provide a warm environment for my plants, and a very nice place to enjoy cold Colorado winters!
    Although not everyone has the resources that I have, a system like min can be set up and built by a local plumbing/hvac contractor. And will supply years of cost free heat for your greenhouse.! NOTE:THE SOLAR PANEL MUST BE COVERED DURING THE SUMMER MONTHS TO PREVENT OVERHEATING THE GLYCOL IN THE SYSTEM!

    Reply

  8. Gloria says

    I’ve been researching and planning to build a greenhouse. Your article helped tremendously AND it made sense! Thanks

    Reply

  10. Susan C. says

    I’m new to green house growing
    , we have a wood burner so I will try the bucket method
    Thanks for the tips realy enjoyed reading all the ideas
    What veg can I grow over winter months in greenhouse also love the compost bin idear so will get myself a black box

    Reply

  12. Ashley says

    Hello! Wonderful article! How deep should the U shaped PVC pipe be buried and do both ends open into the greenhouse?

    Reply

    • Chris says

      Pipe should be below YOUR FROSTLINE…each area has different depths…the colder your weather the deeper your frost line…search zip code on line!

      Reply

  14. Kim says

    I have just lined my 6x6x6 greenhouse with bricks on the floor, would putting black plastic over them work as well as painting them?

    Reply

    • Reuse Grow Enjoy says

      While the plastic will help some, the paint works best. That is because the plastic has a gap between the bricks and does not heat as well as the paint on the brick.

      Reply

      • Mandy says

        Thank you so much for this helpful information. I just got a greenhouse for Christmas but it is the metal frame with plexiglass. I’m not sure how well I can insulate it but I’m going to try. Ohio weather dips to the teens. Hoping to grow my own flowers to keep costs in planting down. Also some food

        Reply

  15. Karen D. says

    I enjoyed your article so much! My little boy and I are passionate plant lovers and we plan to build a greenhouse for the winter. It’s a great way to spend time with my family. Thank you for the tips you used in your article. I can’t wait to read it to my boy!

    Reply

  16. Linda says

    Thank You for your ideas for heating a greenhouse in the winter.. I have two 5×5 tepee shaped greenhouse’s from Aldi’s.. What would be the best way to heat it.. It does get pretty cold in Southern Tn..
    Thank You

    Reply

    • Reuse Grow Enjoy says

      With it being tepee-shaped I am guessing it is made with just a thin sheet of plastic? Those normally do not hold the heat really well. Depending on how cold it gets where you are, you will need to use one of the hotter heat options such as the hot ash bucket. Just be sure there is nothing around the bucket and that it is not put near the plastic.

      Reply

  17. Laura says

    Wonderful and very informative article.
    We are planning on doing a large green house 20×40 and a smaller one 10×10.
    Everything here has given great and very useful ideas.
    Thank you so much

    Reply

  18. AvgGrandma says

    I came for the heating tips for my greenhouse. Glad I stayed for the comments well done my friend all great ideas, and I love the sassy comebacks.

    Reply

  19. Pascale says

    Thank you for the info. I have a 10 by 10 greenhouse and some ‘windows’ leave a small opening. I think it will be ok because I grow winter crops in the winter so I should be fine. I decided to switch crops because I love Cauliflour, Broccoli and Brussels sprouts. I potted some of my summer crop and keep them inside the house so they can keep producing under grow lamps. This is the first year doing this. It is slower but it works and after the last frost I won’t have to grow new seedlings. I am excited about it. My plants will be stronger, produce more and bigger. 🙂

    Reply

    • Reuse Grow Enjoy says

      Happy gardening! Let us know how your winter crops turn out. I too grow a few summer things indoors with lights as some just do not do well in the greenhouse in the winter even with heat.

      Reply

    • Danie says

      You could use spray foam around the windows to seal them, you can buy small cans of spray foam at lowes or stores like lowes (moat hardware stores will have it), I have used it to seal holes in my hay shed and other small holes that needed to be filled in my barn.

      Reply

  20. Sharon says

    Loved your article… and the comments were great… especially the comeback to the person who does not understand ads…
    I live north of Amarillo Tx. We are building a new greenhouse for us. We are using recycled windows x 2
    5×6’ for the front to face the south.. but your ideas are
    great for closing off the cold drafty area.
    I like not using electricity but if one has a source I like using the pads under the trays for starting seeds. Keeps them warm and not heating the house.
    One comment about changes crops! Brilliant!
    Enjoyed your informative site.

    Reply

    • Reuse Grow Enjoy says

      Thank you, Sharon! I love the idea of making a greenhouse from recycled windows! Feel free to come back and share a picture when you have it up. Happy growing!

      Reply

  21. Tannis says

    Thank you for all your information. I love the idea of the woodstove ashes heating the greenhouse. We too burn wood for heat. We plan on building a greenhouse from the old windows of our house renovation. Enjoy your site.

    Reply

  22. Irina M says

    Dear author, i am located in Ontario, Canada (zone 4) . The temperature at the winter can drop to -39 in our area. Just wondering if you have any idea how to keep greenhouse warm during the night in this case? I guess wood stove is the only option we have. Thanks for sharing your ideas with the world.

    Reply

    • Reuse Grow Enjoy says

      Wow, that is really cold Irian! In that case you will need some really good insulation around your green house with just the roof exposed to get the sunlight. As for the heating, yes I think a small wood stove would be your only option for temps that low. Just be really careful not to have the heater right by the plants or the walls of the greenhouse. If you give it a try, let us know how it works as I am sure there are others out there looking for the same info.

      Reply

  23. Sabrina says

    For anyone wanting a winter greenhouse, there are apps now that use AR to see the sun trajectory and shadows for different days pf the year. I found it useful as the sun is so much lower in winter, it’s hard to imagine the amount of space needed for it to remain in full sun!
    Getting mine in full sun + raising chicken inside of it in winter (I had closed, dark nests for nights with full moons) + having lots of compost or piles of manure in the greenhouse are my top 3 favorites to keep it warmer. I use mine all winter and I’m in cold Quebec! No electricity!

    Reply

  24. L. Rotor says

    A bit disappointing. I thought this would cover things like a stone or brick tunnel on the ground across the north side of the greenhouse with a way to have a fire at one end inside one end of the tunnel, and the ventilation stack at the other end so the heat has to travel the length of the greenhouse, warming the stones or bricks on the way and slowly releasing the heat. None of the methods mentioned in the article would keep plants alive in minus 40 degree nights. Clearly this article was written for people living in a place without real winters. However winters are becoming much milder — but not milder yet to allow for this to work in a place with a real winter. I had hoped to learn something, as I have been thinking for some time about how to grow things in a greenhouse over the winter or at least extend the season more at both ends than just what one can do with a regular greenhouse, but I didn’t learn anything helpful.

    Reply

    • Reuse Grow Enjoy says

      Sorry you did not find it helpful. Most people do not deal with winters of -40 degrees so these methods will work for them (such as myself). If you are dealing with winters that cold, you will need a more insulted greenhouse as well as some type of heat such as a gas or wood stove.

      Reply

  25. Anonymous says

    Thank you for the article. It is very useful.I plan to use the information for my new greenhouse coming soon.

    Reply

  26. Paula says

    Thank you for the article I’m wondering if I could fill up black totes full of water without covers will work as well as the jugs.

    Reply

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