Making a sustainable greenhouse without disposable plastic

I have hesitated for a long time at trying to make some kind of greenhouse or hoop house. It seems like it should be easy; but it is too much a breach of my values to use flimsy plastic that will degrade after a few years and need to be replaced. Old windowpanes also don't seem particularly easy to come across. Plexiglass does seem like a good option--much more durable and long-lasting--except that it is also very expensive.

For context, I'm thinking of making something small on the side of the house for growing nettles and other greens directly in the ground throughout the winter. But we can also widen the discussion to talking about all different kinds of greenhouses more sustainably. I'm looking for thoughts, ideas, questions--anything on the topic.

Hopefully we can figure out something better together.

This is always a tricky thing, sustainability of a greenhouse, and interesting topic. Here a few of my thoughts:

So, if you just want to manipulate the microclimate, check out the fruit walls on lowtechmagazine:
https://solar.lowtechmagazine.com/2015/12/fruit-walls-urban-farming-in-the-1600s/



Otherwise, you have different options to build a greenhouse:
-Plastic films (lasting 1 to 8 seasons, depending on quality)
-Polycarbonate, plexiglass, and other thick and stable plastics.
-Glass

Plastic films have the least embedded energy/carbon/petrol. Important to use UV stable film, as otherwise become brittle.
Thick and durable plastic may last longer (if of good quality!) but have much more embedded energy/carbon/petrol. They may become brittle and break into small particles
Glass require energy/carbon/petrol to melt, however does not pollute itself, as it is inert. Often forgotten, is that glass can be found second-hand (often for free), and if you are flexible with building pattern, you can have a low carbon footprint. Hail is one of the dangers with glass, except when you have bullet-proof windows.

One way to look at the sustainability is: how much plastic film do I use for a tunnel, and how much plastic would I buy if I buy the products instead of growing myself?

Edited to add link to picture from the lowtechmagazine, it is highly a recommended lecture, as it goes into the history of greenhouses and several alternatives.

Some sort of greenhouse is on my wish-list too, but there are soooo... many considerations.

1. I have been cautioned about lean-to green houses if the house wall has insulation in it, unless you are sure you won't end up with moisture trapped in the wall causing it to rot. (You can be changing the dew point within the wall if I recall?)
2. That said, I did read the Chinese green house book cover to cover, and they use an earth-bermed north wall very effectively to moderate temperatures.
3. It's important to know how much natural light you will get during the period you want to grow things. I could use one for some season extension, but from November to February, we have so much cloud cover, and such short days (about 46 degrees latitude), that actual growing would require extra light even if I could manage a passive heat system. Elliot Coleman's book talks about "holding" vegetables, but not actually "growing" them.
4. The thought of how quickly cheap plastic degrades, and lack of true recycling for it in most places, is a genuine concern. If I don't use glass, I would want to buy the expensive plastic and it still has a lifespan far shorter than glass would. We don't get hail, but we did have a pile of green houses collapse during a worse than usual snowstorm. I could easily design to avoid that.
5. To be big enough to be truly useful, it needs to be a genuine building, so it won't easily sneak under the radar where I am. Small greenhouses are more prone to extreme temperature swings.

I can really empathize with your concerns, Maieshe. There is no "1 right" answer. If you do start looking for glass, look for patio doors as they are tempered glass which is a little safer.

There are many non-glass coverings today that claim a twenty year or more life span.  There are many advantages for each type of covering.  Careful research on your part will I'm sure lead you to the right one.

The only other thing I can offer - I've only once heard someone say that their greenhouse was too large.  That was from a commercial grower/nursery owner bemoaning the 4 thousand dollar per winter heating bill using gas.

Peace

If I had funds for it, I would look at the thick double wall polycarbonate. Not cheap, but you get what you pay for.

But an idea for free stuff: what about specialized plastic repurposed from large commercial greenhouses? I believe they replace it every x years when it's not reliable enough for their big spans (too much risk). But for a dinky DIY greenhouse I could double it up and give it years of life. It's going to the dump sooner or later -- might as well be later IMHO.

Thank you all for your good answers so far. Since we get very little hail here, I'm now leaning a bit further towards glass, but I would need to figure out where to get it--contact local companies that work on houses, maybe, and learn whether they have excess windowpanes? any other good ways/places?

I do really like the idea of making a Chinese style greenhouse with a berm on the north side. I know a perfect hillside for doing this, where I've already made an earth sheltered cold frame with a repurposed plexiglass plane. The soil is silty/sandy there, so it has good drainage, and it is perfectly south facing.

I agree, reach out, ask around. I bet there are a ton of old windows being trucked to the landfill, and the contractors would happily drop them off at your place to save the landfill fees.

But figure out what you want first. Double pane? Single pane? Wood frame? Aluminum frame?

The sun goes through the glass, rather than bouncing off at an angle, if the rays hit at a right angle. Since the glass is fixed, but the angle of the sun changes, as you make your plans, you need to consider what time of year, the most sun will be needed and calculate based on your latitude.

If I were to try winter solstice growing, the glass would need to be near vertical, but by the spring equinox, some angle would be helpful.

This is why in some situations, having adjustable angle solar panels is important. With better panels and more knowledge of how heat affects efficiency of them, some people are installing theirs vertically in fields because the panel's increased efficiency due to being cooler, off-sets the less efficient angle.

Greenhouses have similar compromises - too often they are too cold in the winter and promptly overheat in the summer! Plants don't like either extreme. Thermal mass is your friend!

For sourcing glass, don't forget premium shower-surround installers who sometimes throw away big sheets of tempered glass. It isn't just windows!

I am a dedicated re-user and up-cycler.
My project greenhouse has lost two panels to breakage.
One  repurposed patio door broke for no apparent reason, and the storm door glass blew the roof after years of seeming to be firmly attached.
If I had it to do all over again, I would seek out used piece of green house or construction plastic.
Plastic is already every where.
As long as you are not bringing more plastic into existence, I say use that which already here.


I have also thought about alternatives to plastics.
Aluminum or steel screen matrixial coated with a natural wax or resin is the best I've come up with.

Looking at it a different way, providing light and warmth for plants is the goal.
At one point gas lanterns were used to effect the day length reactions of plants.
Wood or bio gas lantern might be able to fill this role.

Electric lights  could be run off solar or wood gas.
Combining any artificial light source with hyper insulated walls might be enough to provide warmth to cold season plants.
Solar thermal water heaters and/or hydronic wood gasification would be my choices if more heat was needed.

A glass bottle wall could allow in heat eliminate plastic and  conserve imbued energy , but it is a huge investment of labor.

Translucent fiberglass is an option that may be somewhat more sustainable than plastic. Rigid fiberglass is something like half glass half resin (commonly polyester). So it’s not plastic free, but lower plastic content and because it’s durable and long-lasting you’re not continually shedding and replacing plastic.

Here is one company’s comparison of vinyl and fiberglass roofing:

https://www.westernstatesmetalroofing.com/blog/fiberglass-roof-panels-vs-pvc-roof-panels

Of concern from that link:

The light penetration of fiberglass roof panels is reduced overtime. PVC panels have a transparency that is similar to glass and makes it the superior choice when light-permeability is a top concern.

I wonder how much it degrades.

Mk Neal wrote:Translucent fiberglass is an option that may be somewhat more sustainable than plastic. Rigid fiberglass is something like half glass half resin (commonly polyester). So it’s not plastic free, but lower plastic content and because it’s durable and long-lasting you’re not continually shedding and replacing plastic.

[...]

In sustainability, you have several levels, here according to Kramer 2017, which is an expansion of the Reduce, Reuse, Recycle motto.

Refuse
Reduce
Renew/Redesign
Reuse
Repair
Refurbish
Remanufacture
Repurpose
Recycle
Recover

By using rigid fibreglass, you on the one hand reduce plastic production, on the other hand you make reusing, repairing, recycling much more difficult. Depending on your context, it may, or it may not, be more sustainable.

You'll probably see it anyway, but this thread just popped up about an old Korean technique of making greenhouses out of oiled paper!

it's a lot work but old windows are great. i built 2 with 100% scavenged windows (we have a yearly "heavy pickup here, i have a truck)

the front/first i made the mistake of regular lumber and exterior white  paint - eventually it rotted enough that hurricane fiona wiped it out - it will be rebuilt next year with pt and bare glass panes ( i have a plan ;-)

the back/second i made with non-painted pt lumber and it is holding up great BUT it has a 6 mil plastic roof that lasts 2-seasons - 15 bucks to replace... i have some used plexiglass coming free from a porch rebuild that will replace the plastic next spring.

the third gh to be built next year will combine the best of both and be bulletproof and last many many years - it will have a glass roof and maybe even solar panels at the top..

spacious greenhouses are game changers in northern climates - even unheated greenhouses.. i am eating kale, green onions etc. by mid march, tomatoes until december

best of luck!!!

Those cheap plastics that break down after a couple of seasons are a real issue, and sourcing old window panes is like finding a needle in a haystack these days.
Plexiglass is definitely a solid option, but yeah, it’s pricey, and that can be a dealbreaker for a lot of folks. One idea might be to get creative with materials that are durable and have a smaller environmental impact.For example, you could explore using recycled materials. Sometimes you can find discarded glass doors or windows on sites like Craigslist or Freecycle. These might not be traditional greenhouse materials, but with a little ingenuity, they can work well and last a long time.If you're up for some DIY experimentation, you could also look into using old metal or wood frames and covering them with polycarbonate panels. These panels are more durable than typical plastic and offer good insulation, so they might be worth the investment if you can swing it.

Jay Angler wrote: look for patio doors as they are tempered glass which is a little safer.

Yes, but be sure you are using doors made pre-1987, when glass doors and windows were required to block UV rays. I tried growing plants inside a home with newer windows and learned this the hard way.

I have an earth-sheltered greenhouse that's in process, for the roof I sourced double-wall polycarbonate that was $$ but should last for well over a decade. I've been collecting old windows for a long while, and found a few really good options - Habitat for humanity re-stores have patio doors for often less than 10 bucks! And other windows, but the patio doors are the best bang for the buck (the trade off is that the doors are all slightly different sizes, makes for interesting planning); and glass from non-window sources like glass desks and glass cubes - I'm not sure the UV permeability so I wouldn't make these the bulk of a project, but they are sturdy and often free.

I also have a hoop-house with plastic liner. I share your concerns about the durability and eventual non-recyclability of the material, but it has lots of important advantages! Even with a few holes from when the entire structure blew up the hill a few years ago it still works great, and I have some repair tape that has closed the worst ones, so it's not a total loss once it starts to go. I've also used pieces from an older structure that came with the property for a ton of DIY projects - keeping dust from the chicken side of the shed off supplies in the garden side of the shed, adding a waterproof layer to shed improvements, making small cold frames for greens, keeping a pile of lumber at least a little sheltered from the elements... you get it.  In my case there was no choice but to use a soft liner for that structure, it has to come down each year to avoid being declared a permanent structure and running afoul of zoning laws.

I've also used pieces from an older structure that came with the property for a ton of DIY projects - ...  In my case there was no choice but to use a soft liner for that structure, it has to come down each year to avoid being declared a permanent structure and running afoul of zoning laws.

This is why I'm finding the picture of the greenhouse roof so intriguing from this thread: https://permies.com/t/262705/Medieval-Korean-oiled-paper-greenhouses.

If you can take a structure and design it with easy to remove panels - easy like wing nuts on fixed bolts sort of thing - then it is no longer a "permanent structure", but the plastic would only get exposed to UV when needed, and if a single panel was damaged, it wouldn't require replacing a large sheet of plastic.

Just because the structure is not "permanent" by the rules of the bylaws, *doesn't* mean that one shouldn't build it to a standard that will be safe and last a long time. I don't want my "temporary" structure taking flight in a windstorm and landing on a neighbor's property and causing damage, let alone having the potential to hurt someone!

This thread makes me think about flat white sheets. The corners could be attached with rope like the modern triangle shade fabric. The light could still come through and wind would be minimized. Surely it could raise the temperature a little. I might try something like this myself.

If something like a sheet wasn't strong enough on it's own maybe a screen could be used behind it.
With the added benefit of during hot weather, being able to remove the sheet and let air flow through.

On ewetube there is an instructional video on how to make a sheet waterproof, by using wax and mineral oil.

Thanks for posting the link to info about fruit walls, great reading.

I tried the hoop style covered in plastic. it worked for one year, then the plastic got ripped up. The plastic was the sheet plastic you buy in a roll at Lowe's or Home Depot.  I then bought plastic from the greenhouse mega store that was supposed to last for 5 years.  Some of it is still being used for covering plants over 5 years later, but the hoop house just didn't work well for me.  So on one of those good years when I sold a lot of goats, I used some of the extra money to build a green house that was framed in pressure treated lumber.  We covered the exterior with the polycarbonate stuff that is single layer that you buy in sheets at lowe's or home depot.  It has the wavy corrugated thing going on.  Well, after one year, it got brittle and you could break pieces off with your fingers or if a board leaned against it too hard, it wold crack and break. I was so freaking mad.  Spent about $1200 just to cover the green house it is a 10 foot by 10 foot and we even covered the roof with it.  

At our local livestock auction people bring in other stuff to sell that sometimes there are piles of windows.  I bought two piles of window for $6 dollars each.  I removed all the brittle polycarbonate on the walls and replaced it with windows.  I put a metal roof on the green house and insulated the roof.  It works pretty good and I wish I had just bought the used windows in the first place and saved myself all the hassle.  The windows don't hold in the heat as much as the polycarbonate stuff did, but they do okay and I don't have to worry as much about things getting too hot. I only use the greenhouse in the late winter early spring to start plants.  I save a couple hundred a year just starting my own tomato, pepper, broccoli and cauliflower plants.  

So I would suggest if you want to use the windows to cover a greenhouse, look for local auctions that sell all kinds of stuff. We have several in our area, look on craigslist and perhaps facebook.  

I do have a piece of the stuff that looks like corrugated cardboard polycarbonate and I use it for a window on my chicken coop.  If I could afford to cover a greenhouse with it I would because it is tough, it has lasted for over 10 years and is still going strong and it is still flexible and not breaking.   But I cant afford this stuff right now.  

Just my experience with different materials , hope it helps

Depending on the size of the greenhouse, and the time you have available to replace the plastic every couple of years, it might help your conscience if you could get the plastic secondhand for free?  I've made more than one hoop-style greenhouse this way.  You can scrounge mattress and furniture store dumpsters....all of that stuff comes in huge plastic bags, which can be cut open into flat squares and rectangles.  Patch small holes with tape and then "weld" the pieces together by passing a folded seam through a candle flame, and you can get as big a piece of any shape you like.  

I have a 37' X 13'attached greenhouse on my house. After years of waiting for funds for something better I used super cheap second hand sliding door double pane tempered glass to close it in. I'm still nervous when spring storms drop large hail and I shovel it if the snow is deeper than six inches but at far so good.

Hi there! I totally get where you’re coming from. Building a greenhouse or hoop house can feel a bit daunting, especially when you want to stick to sustainable materials.

Plexiglass is a solid option since it’s durable, but I understand the cost can be a hurdle. Have you considered using polycarbonate panels? They’re often used in greenhouses and are more affordable than plexiglass while still being quite durable. They can withstand the elements better than plastic film and offer good insulation, which could be great for your winter greens.

If you’re open to a more DIY approach, you might look into using reclaimed wood for the frame and experimenting with polypropylene or woven greenhouse fabric. These materials can be more sustainable and less expensive than traditional plastics, plus they offer good light transmission.

For something even more innovative, you could try cob construction for the walls, which is made from clay, sand, and straw. This method has a long history of use in gardening and can provide great thermal mass. On the roof, consider using glass bottles or old windows if you can source them locally. They may take a bit more effort to work with, but they can add a unique look to your greenhouse and reduce waste.

It's fantastic that you're focusing on sustainable options! I’d love to hear more about your ideas, and if you decide to go for it, please keep us updated on your progress! Let’s brainstorm together and find the best way to create a functional and eco-friendly space for your nettles and greens!

I had a dream of an old window greenhouse. When my son said let's build a greenhouse, and bought wood for the frame. It didn't take long before I realized old windows were not going to happen. Where I live they are very hard to find, and any I did find were very expensive. I will save you the long 2 year multiple plans story.  My nephew was remodeling this house, and gave me a  couple aluminum windows (not beautiful old wood windows, but functional) and 3 sets of sliding glass doors, that fit the frame almost perfectly even though it was not built with them in mind. I guess it was meant to be. The small top windows I made out of wood and shower glass I was given.  All in all it isn't anything like my "dream greenhouse" but I love it.  Most people probably aren't that lucky, but I don't imagine there's a lot of use for old sliding glass doors. Maybe contacting window, or construction company's that remodel homes.
Be flexible and think outside of the box. Shower doors, glass out of old consoles, or doors.  I was going to use corrugated steel for the bottom of mine, because I had it, before I got the doors.
I love my greenhouse. It's not perfect, but I learned a lot, I had fun with it, and I'm really glad I built it. Good luck

Both shower doors and patio doors tend to be made out of tempered glass which is an asset near the ground as they are made not to break as easily as usual window glass.

The downside of most "plastic tunnels" is that there's often no easy way to reduce the amount of glazing, or insulate areas that are effectively loosing warmth more than they're gaining light at key times of the year.

Great to see Jen's upcycled glass greenhouse!

There are several sustainable alternatives to traditional greenhouse materials that align with your values while ensuring durability and efficiency. Here are some eco-friendly options:

🌱 Reclaimed Glass – If old windowpanes are hard to find, consider reclaimed glass from construction sites or recycling centers. It’s durable and provides excellent light transmission.

🌍 Polycarbonate Panels – A long-lasting alternative to plexiglass, polycarbonate is UV-resistant, strong, and energy-efficient.

🔬 ETFE Film – A high-tech, lightweight material used in modern greenhouses. It’s more durable than polyethylene and has excellent light diffusion.

🍄 Mycelium Insulation – If insulation is a concern, mycelium-based materials can provide natural fire resistance and carbon sequestration.

♻ Recycled Plastic Sheeting – Some manufacturers offer non-toxic, UV-resistant plastic sheeting that lasts much longer than conventional polyethylene.
For your small greenhouse project, a combination of reclaimed glass and polycarbonate panels could be a great solution.

I am planning it!

What I am hoping to do is to make an oiled paper or cloth covering. Trying to find the right cloth or paper is what I’m focusing on now—a combination of strong and translucent ideally. And what might the best oil be? Linseed? Tung? Beeswax is rather too expensive for a non-beekeeper, and paraffin is a possibility but not my first choice.

I soaked some ordinary printer paper in oil and it lets about half the light through. Muslin might be a possibility too.

My plan is to make a rocket earth heater like the one from the Wheaton Labs video (I can’t find it now)—running a metal pipe through the ground so that the heat is absorbed and slowly released. And, to add on to that, have a framework supporting the greenhouse covering.

This is one of the inspirations. Especially since reading Pearl’s cattle panel thread, I’m thinking of using them as the framework. But I may end up making something from pole wood instead.    

That's awesome, I love your out of the box thinking.
Most cattle panel are 16' long . It depends on how tall you want it.I think mine are about 7' high, and that gives me about 4 1/2 to 5 foot space. But mine is in a raised bed so it's elevated 18". So it really only about 5 1/2 ' tall.  You may have to connect 2 panels together to get the height and space you need.  Good luck.

Jen Fulkerson wrote:That's awesome, I love your out of the box thinking.
Most cattle panel are 16' long . It depends on how tall you want it.I think mine are about 7' high, and that gives me about 4 1/2 to 5 foot space. But mine is in a raised bed so it's elevated 18". So it really only about 5 1/2 ' tall.  You may have to connect 2 panels together to get the height and space you need.  Good luck.

You are right, thank you! Not one but as many as are needed for the given size.

The one in the video is slightly sunken into the ground, adding a little extra height for walking. Though it has been a while since I watched it.

A paper expert and photographer I know says that hanji or any other paper likely has to be replaced yearly which is certainly something to consider. It had crossed my mind but I didn’t think of it too deeply. He says tempered glass is likely a good and durable option: if more expensive in the short term, less so in labor and materials both in the long term.

Maieshe Ljin wrote:A paper expert and photographer I know says that hanji or any other paper likely has to be replaced yearly which is certainly something to consider.

This would be a great thing to test using a small wood frame with squares where you can glue paper on. It would have to be tested by each person considering trying it.
1. Are there different papers that cope better or worse in your climate?
2. Does slope matter?
3. Does the type of oil matter?

We can get extremely heavy wet snow and lots of rain. Things never dry out in the winter. I expect paper wouldn't work well in my climate, but I can imagine climates where it would work better than cheap plastic which rarely lasts 3 years and shreds and isn't easy to recycle.

I understand that most modern window glass has characteristics that block UV light which the plants want, but people don't want it fading their furniture and carpets. I need to do more research on how bad that effect really is, because sliding glass doors are easy to get here.

One time I bought some them clear plastic version of metal sheet roof panels from the hardware store and used them for a greenhouse frame. Grab a box of roofing screws/washers. And they're fairly easily to cut. I usually used the clear plastic liner for painters to put on the floor, with a staple gun and some plywood. Not sure about the disposable part on these though.

If you have the funds though glass be your best yet, glass is durable and friendlier with sunlight. They also have biodegradable plastics made from hemp, banana fiber, etc. Not sure if companies specialize in paneling specifically so that may end up being expensive and not practical.

Sounds like youre onto something with the paper thing. Hope that worked out for ya.

I would check places like habitat for humanity. Maybe even contact glass installer's and construction companies that specialize in remodeling. It seems like they may give you old shower doors, or sliding glass door, free or cheap. If they are old it seems like it would cost them to take them to the landfill? Just a thought 🤔

I was in town a couple of weeks ago and saw where a commercial unit in a strip mall was being renovated between businesses. They were replacing two big metal-framed glass doors. When I came back a couple nights later to put them in my truck, they were gone. But that kind of construction project might be a good place to keep your eyes open.