There are a variety of materials that can be used to cover a greenhouse today.
With the current explosion of interest from both commercial farmers and backyard gardeners, the options for materials are constantly expanding. Greenhouse covering material includes:
2-Layer Polyethylene Covering Later Patched w/ UV-Resistant Greenhouse Tape – You Never Know What May Damage Your Covering! Photo Courtesy: Photofarmer @Flickr
- Glass
- Polycarbonate (rigid panels or flexible rolls)
- Polyethylene Plastic film
- Polyethylene Panels (semi rigid panels or flexible rolls)
- Fiberglass (rigid panels or flexible rolls)
- Acrylic (rigid panels)
- Vinyl
Since we had already decided on using PVC pipe for constructing our greenhouse, we would not be using any solid panel type material to cover the greenhouse, but we still estimate the cost to cover a small greenhouse ( 5 X 10 foot base 4 – 5 feet tall) below for each greenhouse covering material for comparison purposes.
We also estimated the cost to cover a typical sized hobby greenhouse (10 x 10 foot base 8 feet tall). Keep in mind, these costs are for the covering material only. Any clamps, fasteners or furring strips would cost extra.
Glass is the Traditional “True Greenhouse” Covering Material
Glass has been the traditional greenhouse covering material.
Chances are, the first glass greenhouse you saw years ago was made from hundreds of glass panels.
Glass requires a very costly and sturdy structural system, but if constructed well, can last for at least 30 years and and clean glass always allows good light transmission.
The main problem with glass is that is a poor insulator unless you use double or triple panes. Glass is also difficult and expensive to replace if broken.
A small A-frame greenhouse with a 5 X 10 feet base, standing only 4 – 5 feet tall would require between 114 – 137 square feet of surface area to cover.
We looked up the price for two thicknesses (3/16 and 1/4 inch) for both annealed and tempered glass and found it quoted at between $5.78 to $8.44 per square foot.
Even if we could find glass for $4.00 per square foot, the cost for the glass alone to cover a small greenhouse would range between $457 – $1155.
The glass for a normal hobby-sized greenhouse (10 X 10 feet base; 8 feet high;420 square feet of glass) would cost between $1680 to over $3600. You can quickly see why other materials are being used to cover greenhouses.
Polycarbonate Greenhouse Panels and Rolls
Single vs Double vs Triple Layer Wall Polycarbonate Panels. Photo courtesy of Colorado State University Cooperative Ext.
Polycarbonate is a very strong and light-weight material. Panels made for outdoor use have UV treatments that help prevent yellowing and deterioration from sunlight and are guaranteed for about 10 years.
Brand names of polycarbonate panels include Dynaglas, Lexan, HighLine, Sun-tuf, Tuffak and Zelux. Polycarbonate panels are available in various thicknesses from 0.03 inch (0.79mm) to 1/2 inch (12.7mm)
- Corrugated Polycarbonate Panels – rigid panels – single wall construction – cost $4.71 per linear foot (50 inches wide)
- Polycarbonate Panels – rigid panels – twin wall construction with air space in between for added insulation – cost $51 for one 4 x 8 foot panel 6mm thick
- Polycarbonate Panels – rigid panels – triple wall construction for additional insulation – cost $117 for one 4 x 8 feet panel 16mm thick
- Polycarbonate Rolls – flexible sheeting – twin wall construction with air space in between added insulation -cost $6.17 per linear foot -rolls are 49 inch wide)
The Polycarbonate prices and cost estimates have been updated.
The cost for covering the very small A-Frame greenhouse is much more economical using polycarbonate panels.
The cost would range between $204-$255 for 6mm twin wall panels and between$468-$555 for 16mm triple wall panels.
The flexible twin wall sheeting would cost slightly about the same, but would require a solid frame centered on 49 inches. A 10 x 10 foot hobby greenhouse would cost about $1600 to cover with the 16mm triple wall panels.
Acrylic Greenhouse Coverings
Double Wall Acrylic Panel
Most people are familiar with acrylic skylights and other “Plexi-glass” materials – (other Brand names include: Acrylite, Lucite, Optix, Polycast and Aristech) acrylic is very strong for snow, strong winds and even hail impacts, but very specific attachment requirement due to expansion and contraction.
Acrylic is also very expensive, but can last 20 years, so one manufacturer claims it is cost effective over the long run, especially in commercial greenhouses where heating costs can be reduced up to 30%.
Though described as rigid panels, acrylic panels are flexible enough to be molded over shallow arcs. Acrylic panels are available in several options:
- Single Layer Acrylic Panels – Cost is about $90 for one 41 inch by 8 foot panel (corrugated clear)
- Twin Acrylic Panels – air space in between panels for insulation – Cost is about $108 for one 47.25 inch by 8 foot panel (8 mm thick)
- Triple Acrylic Panels – more air space, more insulation
- Quad Acrylic Panels – most air space, most insulation
- Non Drip Acrylic Panels – one side treated to prevent buildup of condensation, which increases light penetration and reduces damage to small plants from dripping water
- UV Blocking Acrylic Panels – to protect UV sensitive materials inside the greenhouse
The cost for covering the very small 5 x 10 foot A-Frame is with acrylic panels is about the same cost as glass.
Because the single layer we found listed is made in an unusual width (41 inches), it is about the same cost as the twin acrylic panels that are produced in 47 1/4 inch widths.
The cost to cover the small A-Frame would would range between $432-$540 and the cost to cover a 10 x 10 foot hobby greenhouse would be $1440 – $1512.
No doubt, the triple panels, quad panels and UV blocking panels would be more expensive, but the products must be fairly new, because we could not find any online price quotes.
Polyethylene Plastic Greenhouse Coverings
Polyethylene Plastic Sheeting
As we have learned, all plastic coverings are not created equal. Choosing the Right Greenhouse film (AKA agricultural plastic, poly-film and greenhouse plastic).
- Utility Grade (4 and 6 mil) polyethylene plastic – will last one season exposed to sunlight – do not attempt to use for two seasons – available at most hardware stores – Cost for 10 x 25 ft roll is about $20.00
- UV protection – Protects plastic film from Sunlight – guaranteed to last 4 years – Cost for 12 x 25 ft = $39.00 (6 mils)
- Thermal protection – Reflects IR back into greenhouse – claims to cut heating costs 15- 30% and to maintain higher temperatures at night if you don’t heat – Cost $92 for 12 x 55 ft
- Anti condensation – condensation attached to film can reduce sunlight, also reduces dripping onto plants
- Protection from heat – Opaque to reduce light transmission to 55% – Cost for 16 x 55 ft = $120
Polyethylene is the least expensive covering for a greenhouse.
One 12 x 25 ft roll will cover the small 5 x 10 foot A-Frame two times, so it will cost about $10 to cover with utility grade plastic each year.
It would cost about $39 to cover the A-Frame plastic greenhouse with UV protected polyethylene and even if it only lasted 3 years instead of 4, that would average $13 per year.
The thermal rolls I was quoted are longer, so one roll would cover the A-Frame greenhouse at least three times, so $92 would last for 9 to 12 years, or $7.67 -$10.22 per year.
A 10 x 10 x 8 foot hobby polyethylene greenhouse could also be covered with one 12 x 55 ft roll of thermal protected polyethylene for about $92 and still have about 40% of the roll left over.
Polyethylene Panel Greenhouse Coverings
Polyethylene can also be made into panels, usually with a twin wall construction with air space for insulation in between – can be used to construct greenhouse as rigid panels or can be semi-flexible and be fitted to shallow arches.
UV protected and some are guaranteed to last 10 years. Solexx is a brand name.
- 3 mm flexible rolls with UV protection- Costs $6 per foot for 49 inch wide panels
- 5 mm flexible rolls UV protection – Costs $8 per foot for 49 inch wide panels
The small 5 x 10 foot A-Frame would cost between about $180 and $280 to cover with flexible polyethylene panels depending upon whether we used 3 or 5 mm material and also depending upon the greenhouse being 4 or 5 feet high.
That cost would average between $22.50 to $40 per year if the flexible polyethylene material would last 7 or 8 years. It would cost about $630 -$840 to cover a 10 x 10 x 8 foot hobby greenhouse.
Fiberglass Greenhouse Coverings
Corrugated Fiberglass
Fiberglass panels can be clear or translucent, but still lets about as much light into the greenhouse as glass does, and may allow more light in when the sun is at low angles because very little light is reflected.
Seems as most manufacturers offer a 10 year guarantee against yellowing and structural failure. Seems as though fiberglass panels in the past would begin to deteriorate on the top and expose fibers that would trap dirt. This would block sunlight and require washing and re-sealing.
- Rigid corrugated panels – cost $72 for one 5 oz, 52 inch x 8 ft panel
- Flexible rolls – cost $335 for 4 ft X 50 ft roll
It would require six fiberglass panels to cover the small 5 x 10 foot A-Frame greenhouse if it needed to be over 3 feet tall and would cost about $342.
It would require at least 14 fiberglass panels to cover a 10 x 10 x 8 foot hobby greenhouse and cost a little more than $1000.
The A-Frame greenhouse could be covered with one roll of flexible fiberglass at a cost of $335 with almost half of the roll left over.
A hobby greenhouse would require three rolls of flexible fiberglass at a cost of about $1000, but would have most of one roll left over.
Vinyl Greenhouse Coverings
Vinyl covering materials are primarily for used for a clear “showroom” quality look.
Users are advised by the manufacturer to use only on the ends of the greenhouse so customers could have a nice, clear view of facilities. Not intended for use as covering for the top of the greenhouse.
The clear vinyl “siding” is supposed to last about 4 years and costs $130 for 54 inch by 50 ft roll of clear film 16 mm thick.
We have no intention of using vinyl, but just in case someone else is interested, the cost to cover the 4 sides of a a 10 x 10 x 8 foot tall hobby greenhouse would be $280 for two 50 ft. rolls. The roof would still have to be covered with another material.
Our Choice for a first time Greenhouse Covering
We Used 6 mil Polyethylene Plastic For 2 Seasons
Our choice for a material to cover the A-Frame hoop house (greenhouse) for the first two seasons was the simplest cheapest material.
We used a utility grade (6 mil) polyethylene plastic. It works well with the PVC Pipe structure and is clamped to the PVC pipe with simple homemade clamps cut from short sections of PVC pipe.
If you use polyethylene plastic that is not UV treated, do not try to use it for a second season.
It may look OK at the end of your first season, but it will disintegrate before you make it through the second season, and it is nearly impossible to pick up all the plastic fragments.
We still plan to use the same polyethylene plastic again this year, because we still have enough left over to cover the greenhouse again.
Next time, we plan on using a buy a UV and IR protected sheeting because it will be more economical and less wasteful in the long term and our tomatoes and peppers could benefit from some additional thermal help on our cold nights.
After two growing seasons, the plastic sheeting held by homemade clamps have worked very well.
When fastened correctly and completely closed, the plastic sheeting has even held up to wind gusts of 70 mph, but on an other occasion, when the greenhouse was partially opened for ventilation (and only partially fastened), the plastic sheeting was blown loose by an approaching storm.
The A-frame shaped hoop house also allows the plastic to shed snow without any damage.
Here is also some great examples of mini greenhouses.
Q: What greenhouse covering material are you considering? Please comment below. You may also want to look at our Greenhouse Building Materials page that discusses the pros and cons of different types of materials for the frame.
Hello,
I recently read the article at http://www.homemadehints.com/greenhouse-covering-materials-comparison/ I’m very curious where you got the pricing on the rigid polycarbonate panels. The reason I ask is because its only a fraction of what i’ve been finding.
Thanks,
Tom
Tom: We can no longer find those prices either. The cheapest source we found at the time the article was published is no longer available. We knew this was going to be a problem with publishing prices and then trying to keep them current, but will adjust the current prices for greenhouse polycarbonate panels ASAP.
No worries, I wasn’t able to tell when the article was published only saw the copyright at the bottom of the page so I figured it was at most a year old based on that. Just thought I would ask because I would LOVE to find prices like to build my commercial greenhouse lol.
I just came across this great information! It appears the pricing for polycarbonate panels has been updated from a few weeks ago. I would appreciate if you could mention the brand and the vendor offering the updated pricing. Btw, is the pricing quoted by the sheet without a minimum order, or for bulk/tier orders? I ask because I usually have to replace a panel or two a year to my existing houses though this year I am adding another house and will need to purchase more than two panels.
Thank you!
The Best prices we quoted for polycarbonate were from online vendors (brands unknown). Do online search for growerssupply, greenhousemegastore and advancegreenhouses. Also check farmtek. Check with the vendors for minimum orders and shipping.
Adding another greenhouse? Sounds like you are seriously into greenhouse gardening… If you don’t mind sharing… How many greenhouses do you have? Is this for a business or a hobby? and why do 1 or 2 panels need to be replaced each year? Thanks
Sorry, this isn’t really a reply but a question. I have a roll of very thick yellow plastic that was given to me. I’ve had it on my small greenhouse roof for 3 years now. The question is is it alright to use yellow plastic on another greenhouse I’m building. I’ve read that yellow is a bad color to grow plants under, but this plastic is awesome. It is so thick, but I have know idea what ml. It makes 6ml look thin. Is yellow ok to use?
Yellow plastic will remove some of the yellow wavelength light from the visible spectrum…
Chrolorphyll uses all parts of the visible spectrum except green, but does not use them all equally.
Other photosynthetic pigments increase photosysthesis by using other wavelengths
The only data I can find for yellow plastic is a high school experiment where plants under yellow stained glass did not grow as well as natural light.
Farmtek has great prices for “rolls” of twin wall pc….do the math…..
• Fewer seams and joints.
• Follows the contour of most roof structures.
• Manufactured from double-walled, high-density polyethylene with UV additives for long life and durability.
• Translucent corrugateld pastic transmits about 72% of the available light and has an R-value of approximately 2.
• 4mm (0.1574″) thickness.
Maximum roll size is 250 feet.
Our Price: $9.75/FT<– for a 8ft wide roll….
to get linear foot price for a 4ft wide = 9.75 x 4 =39 (for a 4×8 piece)
39/8=linear ft price= 4.875 linear ft
Basically its Solexx….but cheaper…..
Sorry, it’s not even close to Solexx. Totally different formulation. Look at the warranty. Farmtek has NO WARRANTY. Solexx is warranted for 10 yrs.
I just found this amazingly informative site! Thanks to everyone contributing.
My wife wants me to convert our covered porch off our dining room I already screened and put in a clear storm door from HD, to install clear 0.150″ Evonik precut Acrilite panels above the deck railing and DEFINITELY the suggested Farmtek 4mm below!! Just clearish plastic sheeting last winter helped keep the house warmer. Another inexpensive tip is to cover the already painted deck boards with thick Armstrong vinyl foam backed flooring (stone pattern was nice), totally washable and is bug and draft tite!
Interesting discussion. I used a plastic “drop cloth” from a painting project. The plastic only lasted one year. It is a small green house 2×4 and 5 ft tall. The insulated panels look interesting but sort of expensive. Is the insulated panel the best ?
Hi John: We also still use “drop cloth” type plastic for our greenhouses, but we hate the fact that most of that plastic can only be used for one season, but have not been able to justify the extra cost for UV protected plastic sheeting.
Which is best? Complicated answer and depends upon what your limiting factors are. A small greenhouse like yours will not cost too much either way.
Our biggest problem during the middle of the growing season is cool/cold night time temperatures. We get plenty of heat during the day, so increasing the insulation to hold heat during the night is more important than trapping solar heat during the day. We would benefit from using double or triple wall polyethylene panels on the sides and then covering the greenhouse at night with landscape fabric or a tarp to hold the heat through the night. Biggest problem for that is I am the automation. I will have to cover in the evening and uncover in the morning.
We are considering a hybrid solution for our greenhouse. By that, I mean a more permanent type of UV protected covering for the sides and the door, but still use simple plastic sheeting for the top. I have no doubt that polycarbonate, fiberglass or UV polyethylene sheeting panels will hold up there, which will justify the extra cost.
The roof on our large greenhouse design holds up to serious wind, but would have to be re-enforced to handle the snow load we get here. So we will continue to remove the roof at the end of the growing season. If the roof has to be removed anyway, the cheapest cover still makes sense.The labor to remove and/or replace sheeting on a small greenhouse is small. Obviously, time and labor has to be considered for a large greenhouse.
keep checking at lowes and home depot for damaged panels. I bought some for half price because the ends were dinged up. (I was going to have to cut some off anyway) If you see dinged ones, ask if they’ll give you a discount. With your size greenhouse it should work out good. Just an idea.
Good tip, Debby.
I read somewhere else about using vinyl only on the ends. Have you found out why the manufacturers suggest against using it on the roof?
I think what they mean to say is that vinyl is a good choice for the ends of a greenhouse where a clear view is important, such as a commercial operation wanting a clear view for customers, not that vinyl can’t be used on the roof. Growerssupply recommends that vinyl can be used for “utility doors, panels on existing buildings, canopies or awnings”. I hope this helps.
I’m not sure why you classify fiberglass as opaque, and then go on to say it lets light in.
You might want to call it translucent to avoid confusion.
-Andrew
p.s. love the products and the ideas
You are correct Andrew… Translucent is a better term. I got the term “opaque” from a manufacturer, but the panels are in fact translucent, otherwise they would be not be useful for covering a greenhouse. I will change it.
The writer’s choice of “the cheapest polyethylene” is not cheap because it will break apart in 1-2 years. It is best to buy 5-year polyethylene film. This can be made to last 10 years if you simply apply 2 layers and cover the ends (the stress points) with black or white plastic to reduce UV exposure.
Also, consider the following for other materials.
* US-made polyethylene can be much more clear and long-lasting than others. Be sure to surf for US-made polyethylene.
* Fiberglass is the worst choice: much more expensive than 2-layers of 5-year polyethylene film and does not last longer. The only advantage of fiberglass is in withstanding a snow load. However, you can achieve the same advantage by mounting galvanized poultry fencing (chicken wire) under the polyethylene film.
* Plastic or aluminum “hoop” construction is not the best if you want to reinforce or multi-layer your covering for insulation or a snow load. Get a cheap table saw and rip premium pressure-treated 1×6 yellow pine decking into strips 3/4 inch x 4/4 inch. Bend into hoops and laminate 3 layers, held together with decking screws and waterproof wood glue. Mount 24-in on-center with 1-in poultry fencing on the outside and inside. Mount acrylic or polycarbonate film on both sides of the inner fencing and on the inside of the outer fencing. Cover with 2 layers of polyethylene on the very outside. Use decking screws and batten strips of 3/4 x 4/4 to hold this down. Then there will be essentially no stress points and the outer layers can easily be replaced by unscrewing the batten strips.
* Polyethylene also can do better than multi-walled acrylic for a fraction of the price, simply by mounting bubble wrap on the inside. By itself, the bubble wrap will not last long. However, deterioration will be slow if mounted inside of 2 layers of polyethylene.
* Acrylic film or polycarbonate film can be used to create much more insulation layers than bubble wrap while still allowing enough light through. Acrylic film is more clear than polyethylene and can last longer. Polycarbonate (Lexan) film is even more clear and probably lasts much longer still. However, even though very strong when thick, these are both brittle in film form. If you use this technique, in my opinion polycarbonate is the most sensible considering the labor involved. Polycarbonate will let in substantially more light per layer than acrylic and potentially last much longer. However, it still makes sense to have 2 layers of polyethylene on the outside.
* Vinyl is very clear and generally comes in thick layers. Use vinyl for doors and windows that you want to see through. Of course, hard acrylic glazing can also be used but is much more expensive.
Also, I forgot to mention that white plastic polyethylene coverings allow 50% light transmission and make good shade material in hot summer months. In addition to cooling the greenhouse, this can further extend life of the outer polyethylene from 10 years to 15 or 20.
However, the ideal shade material does not wear out. This can be achieved with trees or vines that sprout leaves in summer and are trimmed back in winter to allow the light in. Aluminum insect screening is also one of the most sensible shade materials, unaffected by sunlight and lasting forever if well handled.
If you buy polycarbonate online, the vendor will charge a minimum “crating” charge of about $100, just because of the way it must be packed. Make sure you add this into your cost, when buying online!
Good to know Annie.
We have not bought polycarbonate online and the online retailer we looked at did not include that fact. I guess you find that out after you decide to purchase.
So what about vinyl fabrics like commercial tent grade or tension fabrics? These fabrics have been used in commercialized structures for a long time now and seem to be gaining popularity. I’ve seen some driving down the road that look like they would last well and still let in good light for growth. Something like these guys make. [Link removed because they are annoying me with phone calls].
Hi John:
Yes, we would love to have something like the structures on that link, but what is the cost? When you have to contact a website for a quote you know they are proud of their product but ashamed of the price. They look very nice and should (better!) last for years.
I called their toll free number but the sales team was “out to lunch”. They wanted my info, but I declined, so I still don’t know the cost. Do you work for this company? Do you know the cost of the smallest greenhouse? I’ll bet it’s close to the per foot cost to build a house.
Since I still have a large roll of 6 mil plastic (polyethylene) sheeting, that will be our greenhouse covering again this season. Since I paid for it three years ago, the cost this year will be $0.00
Another alternative that is widely used are pvc panels. They are extremely resistant to sun damage (including discoloration), weather resistant, and they’re practically unbreakable.
Hi,
Do you recommend using the 6 mil utility grade plastic (PE) sheeting from the hardware store for growing sun loving plants such as okra, squash, and vegetables and dwarf lemon tree that do not adapt well when the night temperature drop below 50F even during the summer months? I can see the advantage of using the plastic covering to keep the plants warm during the night but not sure if it will let enough sunlight in during the day.
Hi Jason:
Yes, we use the 6 mil PE sheeting for our greenhouses and that is what we recommend in our greenhouse books for small greenhouses, but remember it will only last one season in the sunlight. The UV sheeting is more expensive but it will last several years. The UV sheeting is definitely worth the price difference for large greenhouses, but probably not for the smaller ones since the UV sheeting has to be ordered and they have to charge shipping. The PE sheeting is available everywhere, so it is a good choice for people using a small greenhouse for the first time. Just be aware the 10 foot wide sheets may be an inch short.
You are right about warm loving plants and temperatures below 50°F. Every hour the plant spends in temperatures less than 50°F hurts them, so it effects plant growth, resistance to disease and harvest. The 6 mil plastic sheeting will keep the temperature about 3°F higher at night in a small greenhouse area. That doesn’t sound like much, but if you keep track of Growing Degree Days (GDD), it helps add up quickly.
Be aware, it will also raise the temperature up to 130°+F when the sun is up, so remember to vent before it gets too hot. Plastic greenhouses are great on early spring days when temps are in the 50s & 60s (°F) and your little plants are sitting in the 70s or 80s. This also increases GDD. We’ve been playing around with homemade candles that burn used cooking oil to keep greenhouses warmer on cold nights. Look for that post in the future.
In the past, it was easy to find clear plastic sheeting. Now, most plastic sheeting appears very milky. We have used both and can’t tell the difference between plant growth under clear or opaque plastic sheeting. So Yes, plants will get enough sunlight during the day.
The best plan for small greenhouses covered with plastic sheeting is to cover/close the greenhouse in the evening while the temperature is still warm and open or partially open the greenhouse before temperature gets above 90°F the next day.
Good Luck with your greenhouse.
Thanks for the additional tips. It seems that just about every type of the so-called CLEAR plastic sheeting sold in the hardware stores looks opaque (I’ve purchased the 1.2 and 4 mil. from different places). I am surprised to learn that you’ve got same result from both the clear and milky grade plastic. I thought the amount of sunlight does have different effect on the plants. Isn’t that’s why the greenhouse suppliers claim how much more sunlight their sheeting will allow through? And not to forget the needs for shade covering for those lettuce and spinach vegetables during summer months in warmer regions. These are just few ways to control the amount of sunlight your plants will expose to.
The reason I wanted to build a pvc hoophouse is that I missed the Asian squashes, melons, okra, Japanese eggplant, and water spinach that grow so easily in Texas climate. I tried the grow those plants last year here in my new residence in NW Oregon but none produced any crop. I figured that a major difference in the growing environment is the night time temperature (it is constantly at the low 70’s in Texas and 45-50s in NW Oregon).
After I installed the 4 mil. CLEAR plastic sheeting on the hoophouse, it actually creates a moderate shade because it is milky as you put it. Thinking that those plants did so well under the Texas sun, I’ve been going through the trouble to modify the hoophouse so that each morning I can lift both sides of the plastic covering to let more sunlight in and close it before the evening to trap in some of the heat. Doing so is kind of labor intensive and requires 2 people to do the job but at least the plants are doing well so far. The only other way I can find out whether my plants will do well if I keep the plastic enclosed and only open the ends for vent is to build another hoophouse. But that is not in the plan right now.
I look forward to the posts on homemade candle project.
Thanks,
Jason
I read an article once, and I don’t remember where, about using compost and manure to heat a greenhouse. Have you heard of this and if so do you know the details?
A google search reveals dozens of posts about heating a greenhouse with compost. It sounds simple, but it gets complicated.
Here are the basics of heating a greenhouse with compost.
Optimal temperatures for composting is between 43°C and 66°C (109° – 150.8°F). Optimal meaning hot enough to destroy weed seeds, pathogens and insect larvae. But above 60°C (140°F) many of the microorganism that are doing the composting will begin to die, so the pile will need to be aerated to release some of the heat.
Note: I have seen moist hay bales catch fire, so plenty of heat can be created under ideal conditions.
Heat production from compost is dependent upon several factors:
Size of the compost pile
Amount of moisture (50-60% is optimal, too little reduces microorganism activity, too much reduced Oxygen)
Access to Oxygen (surface area of compost pile, particle size of the compost and moisture content)
Ratio of Carbon to Nitrogen (25:1 is optimal – not all compost material is suitable)
Ambient temperature
Under ideal conditions, it will take 2 – 3 days for a new compost pile to reach optimal temperatures. The compost pile will sustain that temperature for a few days, then the temperature will begin to fall again, so new material will constantly need to be added and the pile will need to be aerated. It seem highly unlikely that a greenhouse can be evenly heated with a single compost pile. For constant heat, several piles will have to be in different heating cycles at the same time.
To use compost to heat a greenhouse, there must be a balance between many factors such as:
The amount of compost (cubic feet)
The area of the greenhouse (square footage of floor space for plants and compost and the cubic footage of entire space to be heated)
R value of greenhouse cover
Outside temperature
Moisture and Oxygen available for the compost
Methane and Carbon-Dioxide released from the compost
In our area 42°N and 5,600 feet altitude it would require a huge pile to heat the rest of the greenhouse, but I doubt we can get the compost pile warm enough without supplying outside heat in the first place.
Probably the best use for compost as a heat source would be to heat new seedlings in the Spring. A pallet can be placed on top of a compost pile and the new seedlings can be warmed when placed on top of the pallet.
Evonik industries makes Acrylite in multi-layer panels. It has a 30 year warranty, does not degrade due to UV and should last 30 years.
I do not know how much it costs but it should be less expensive than glass. Now since it is multi-layer it should save on energy costs.
Hi Michael,
Excellent suggestion. I just found this great HomemadeHints website/forum, as my Wife wants us to upgrade the covered porch to a year around greenhouse I previously fully screened and framed in a clear storm door on sale from HD. We are DEFINITELY going with precut Acrylite 0.150″ thick very clear above the deck railings, and Farmtek 4mm 2 layer rolled translucent material below. Clear is mandatory as it is outside the Dining room patio door I added. As I replied to the Farmtek comment (it has not posted yet??) we long ago solved the floor problem with inexpensive but very comfortable Armstrong thick foam backed resilient vinyl flooring, stone patterned and it is washable, bug tite and pet friendly over the deck boards I already painted.
Foam board insulation will go under the deck soon to complete the job, and venting by reusing a DC blower from an over the bed air filter powered by a 25W solar panel I have already.
Solexx Twin Wall Polyethylene covering is a great product. It has a 10 yr warranty, UV protection,and comes in panels and rolls. Not all products have the same light diffusion qualities. This is important as plants light diffuse light. Check out Solexx.com where you can read more.
What material is recommended for a greenhouse located in a climate with temperatures averaging from 28 to 32 degrees?
Lizzy – Are those nighttime temperatures? And if so, what are the average daytime temps?
Average daytime temperature is 32 degrees and 28 to 30 at night. This is along the east African coast so the water is along a bit salty.
Are you near Dar es Salaam? If so, I’m now realizing that your giving me temperatures in Celsius not Fahrenheit. What are you trying to grow that would require a greenhouse since those are fairly warm temperatures?
Yes, I am in Dar es salaam. I want to grow tomatoes and bell peppers. But I don’t have much land and I want them in a controlled environment so as to increase the yield, as opposed to growing them in an open field exposed to parasites and heavy rains.
Lizzy: A greenhouse may help protect plants from insects as well as from other animals that could eat or trample the plants, but my main concern for you will be too much heat in the greenhouse. In our climate, we need to cover our tomatoes every night to keep the temperature up, but if I don’t open the greenhouse every day, the temperature is too high for the tomatoes to set fruit. One season, I had the healthiest looking plants, but almost no tomatoes.
I was taught that when the temperature climbs above 90°F (32°C) during the day and if temperatures stay above 75°F (24°C) for extended periods at night, tomatoes don’t set fruit.
Obviously you must have varieties of tomato that can tolerate the heat in your climate like “Tengeru 97” or “Meru”.
I did some research and see that people are growing tomatoes and using greenhouses in Tanzania and even in Dar es Salaam See here and here.
Also see if these scholarly articles can be of use to you.
My advice is to contact people in your area and see what materials and methods are working best for them. Please keep us informed, we would like to know how your tomatoes and bell peppers do and we wish you have a bountiful harvest.
I know folks who complain about the polycarbonate being too fragile and they recommend fiberglass instead. Do you have any thoughts on this?
I have examined polycarbonate panels, but have not used them on our greenhouse.
This video shows strength testing of triple layer polycarbonate.
Polycarbonate is claimed to be durable if UV-treated. For greenhouses, it is recommended to get multi-wall panels, with three layers being better than two for better heat retention and strength. but these are very expensive.
I checked the warranty on corrugated polycarbonate panels and they have a lifetime warranty against discoloration (Sun damage), but will not have great heat retention.
Polycarbonate coverings should have a relatively long lifespan of 15 years or longer in most regions, but people in very hot (high UV?) climates report issues…
But we don’t know if they use UV protected panels or not?
Clear PVC panels have a 5 year warranty, but again will not retain heat well.
I Don’t know if you’ve ever seen an old fiberglass panels, but I had a relative that covered a patio with corrugated fiberglass panels. They also start to show a damage after 8 or 10 years in the Sun and the low spots in the corrugation collect leaves and dirt. Obviously less dirt would collect on a steeply inclined roof than a shallow one.
What about WHITE PVC PANELS? Do they let enough light in?
I want to build a green house/sun room out of patio doors. Has anyone else done this? I have been collecting free patio doors, but have been told I can’t use them on the roof because they aren’t tempered glass. I know I would need to have heavy duty 4×4’s etc. for framing. Any ideas anyone? I live in Wisconsin zone 3-4. Thanks for any advice. 🙂
My first instinct is to say it is probably against code to build greenhouse with non-tempered glass. Glass could kill someone if they ran into it or if it fell on them.
One thing to keep in mind is you need to make sure the roof has a steep enough pitch to prevent too much snow build up.
I’m not sure 4×4 framing would be necessary unless the door would flex too much in 2×4 frames, but it would also depend on the size and weight of the doors.
Bonnie, glass doors such as sliding glass and patio doors are building code required to be of tempered glass and often are thermal-pane consisting of two layers of tempered glass with an inert gas sandwiched between them. If a faulty seal allows a breach the vacuum is lost and usually presents as moisture buildup the panes of glass. Thermal values are somewhat reduced but not drastically. For someone of the ‘reduce, re-use, recycle’ philosophy, finding a supply of these usually 6’x6′ (approx.) doors is like finding gold in the streets.
I need acrylic,rigid sheet .05mm, abs .09mm, vinyl sheets, vinyl role, bolkout. etc
Thanks
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aaron t. nadar
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We are looking at building a greenhouse in Southern California. We have been looking at using suntuf polycarbonate. My question and concerns relate to heat..
In the winter we get frost and low temperatures in the mid 30s at times. During the summer we get hear as high as 115. Are there any recommendations on the “color” polycarbonate that would support our growing at both temperatures?
Yes I am aware I will need venting and cooling systems for the summer heat. I am currently concerned about the best choice in roofing and siding material. Once this is determined we will work on a plan of action to keep the green house cooler during the summer heat.
From your research, you probably already know the color of greenhouse sheeting material raises very complicated issues.
First and foremost, the most important thing for plants in a greenhouse is to raise the temperature so plants can actually be grown.
Second, plants need full spectrum light to grow their best.
Diffuse light is good in a greenhouse because diffuse light is able to “bounce” around and reach leaves that would normally be shaded.
Clear materials provide very little diffusion and can create hot spots.
Opaque materials provide good diffusion.
Also think about painting the things inside the greenhouse white (framing, benches, etc), so light can be bounced around to be absorbed by plant leaves instead of building up heat.
Pots/containers should be dark colors so the plant roots can be warmed. If plants are on the ground, black plastic or dark much will absorb heat and heat the soil.
As far as color for the greenhouse sheeting material (in your case polycarbonate), color does have an affect on both plant growth and greenhouse temperatures.
Green coverings obviously reflect green light, blue covering reflect blue light and red coverings reflect red light. That is why they appear to us as the colors they are.
But what does that reflected light do to the inside of the greenhouse?
Red sheeting will lower the temperature in the greenhouse, but it also blocks too much of the color that plants need for photosynthesis.
Green coverings block some of the light, so plants don’t grow as well, but the color doesn’t change the temperature inside very much. So it will not help much with overheating.
Blue coverings also block light so plants don’t grow as well, but the color does lower temperatures inside the greenhouse.
It is probably more important to choose opaque (milky) colored greenhouse sheeting materials and then make sure to properly ventilate the greenhouse for best year round growing.
Good Luck and let us know what you choose.
I am looking for a sunroom roof material, Approximate dimensions 4ft x 15ft
This will probably be a stupid question, but will buying UV protected greenhouse film decrease the amount of sun the plants get? I love the idea of UV protected film, but…
Thanks!
Tina – UV radiation is harmful to living organisms, plants included; exposure to UV radiation results in damage to DNA, proteins, cell membranes and other cellular structures, so reducing plants’ exposure to UV radiation is beneficial to their long-term health. So no, UV greenhouse films won’t reduce what the plants need from the sun.
There is so much useful information here! I would like to add one more greenhouse covering option I’ve not seen mentioned and that is a material called SolaWrap. It looks like large bubble wrap. It is super tough, 85% translucent, and UV protected to last up to 30 years. It comes in rolls 4′ and 6′ wide and up to 328′ long. It costs about $1.50 per square foot. I’m not a seller, but it is something I’ve considered putting on a geodesic dome greenhouse.
You mentioned at the beginning of the article that you are using pvc for the greenhouse frame… Please note that many greenhouse plastics will not last more than 2 years; 3 with careful taping in my experience; over pvc without some type of protection between… I learned pvc voids the warranty on those plastics…
I know this is buried at the end of the comments but I hope it helps someone. I don’t work for any one but tried it myself and this is what I learned. You may as well use the cheap one year plastic (and replace it every year!) if you have a pvc frame.
Yes, we are aware about how pvc voids the plastic warranty. We go into more detail about that in our greenhouse plans, but thanks for mentioning it here. Taping the pvc at the contact points of the plastic does help.
I have a hoop type aluminum green house that I need to cover. I am located in northern Indiana. The greenhouse used to have fiberglass covering. I would like to know which is the best option for the cold weather corrugated fiberglass or corrugated polycarbonate.
Having read all commentaries by numerous persons, I found everyone of them very interesting indeed. Please I would appreciate it very much if anyone could offer me a honest advise as regarding my plan to start a fish farm in Nigeria in Africa, particularly in one of a northern Nigeria cities namely; Jos town. In November to January period of each year the temperature weather time it is about coldest period like during the SPRING weather period in Europe continents.Then between March-April months it’s hottest period of temperature of about 45 Celsius to 55 C.I intended to cover the fish pond of 36 pond units wide with a long lasting years UV resistance sheets plastics as roof.And so the advise I am seeking for is that what best material plastic sheets to use to also absorbs sun heat and retains during the night time for fish growth.I will be grateful for your time to provide me with such advise. Also which reliable company can deliver plastic strong sheets directly to me in Jos town or such a company has already appointed and very trusted-worthy sales agent station inside Nigeria that whom full details should also be provided to me as well. Thanks in advance
Mr. Ayuba – By coincidence, I actually have some experience with fish ponds in Africa.
I helped local farmers build fish ponds and grow fish (Tilapia) while I was in the Peace Corp (Sierra Leone) between 1978 – 1980.
It was much warmer in Sierra Leone and cool weather was not an issue, but I actually trained in the highlands of the Cameroons (Kubome fish station, near Bamenda), where their climate was similar to yours because of the high elevation.
You are correct in thinking fish metabolism will be higher if the water temperature is higher. I looked up climate data for Jos, Nigeria and see that your low temperatures average around 13 – 17°C, but climb to 27 – 29°C during the day. The July (rainy season) highs are lower.
First, let me say that farmers in the highlands of the Cameroons were very successful raising fish without trying to increase temperatures of the ponds.
2nd, plastic sheeting (of any kind) is probably not a good long term option for agriculture/fish culture. It will increase costs, but without serious testing, we will not know how much it actually raises the temperature of the water or how the warmer water actually converts into increased fish growth.
I would not assume your limiting factor for fish growth would be the water temperature. Maintaining the balance between high protein food for the fish and high oxygen levels in the water (especially at Sunrise) is probably your limiting factor.
One way to increase water temperature and to also fertilize the ponds at the same time is to build compost piles along the edge of the ponds.
A 36 pond system is an ambitious project. I assume you have some knowledge of fish pond construction and fish culture and/or can visit others that have ponds to see how they are progressing.
Hi there
Am wondering which is better for a green house covering, the clear plastic covering like on the expensive commercial houses or the greenish covering that I see on store models. Will the green color prevent sun rays from coming in or is this a good thing.
Anne – It is best to use clear and not colored so that all wavelengths of color from the sun will reach the plants for optimal growth.
I have been using two sheets of 6 mil utility poly from a hardware store where they give me a contractor’s price of $75 for 20 by 100. I used the clip method as you did using black water pipe for clips because they are easier to open and put on. Used a Jaderloon fan to pressure the two sheets, and that worked well. Planted into the ground which is good and bad.
Varmints think my greenhouse is like going to Florida for the winter. I rotated the sheets every two years and got away with it, using the inside sheet to the outside, adding the new sheet to the inside. That way, if the outside sheet ripped, I still had protection.
I am moving to build the same thing on a raised bed two cinder blocks high. The ground inside the first green house was not healthy enough. This is Texas with high PH, and I need more soil that I can build up. Heat in the winter with kerosene lamps, so that if one goes out, all is not lost.
Warning: Do not use sign board for the ends. It looked wonderful at first, what with the double layer, but the stuff went brittle and crumbled. I intend to use Hardi Panel next time. I like your advice and your practical attitude toward the beginner. Many people cannot afford the high end materials, so you give them choices that work. Keep it coming friends.
I’m intrigued with your concept of using short sections of PVC to create homemade pipe clamps for holding greenhouse sheeting.
Any information on how this is done? Since you were working with PVC pipe I’m going to guess that it would be a lighter gauge of PVC plastic but probably the same size PVC pipe as the frame is made-up of?
Brad – We usually use the same pvc pipe that the greenhouse frame is made from, but have used thicker pieces as well if that’s all we had and they’ve worked fine. We cut the pieces 2-4 inches long depending on if it’s going on curved or straight pieces. It’s explained in our Greenhouse Plans ebook.
Hi Folks
Are the clear polycarbonate panels that you can purchase from your local big box (orange) supply store suitable for greenhouse panels? They appear to be single wall construction, but I would imagine are pretty easy to use once your structure is framed out. Any thoughts and opinions would be greatly appreciated.
Thanks
Vito
Are the panels you are referring to like any of the polycarbonate panels we discussed above?
Hi, we want to build a 200 m2 dome greenhouse, that we also can use for livingroom, etc. During summertime, but we need something that are totally transperant, as glass clear, do you know any material as clear as glass, but still made out of some sort of plastic?
Laila (denmark)
Laila – The only thing I can think of is something like this roll of clear vinyl. If you follow the link, people have been happy with the clarity of it after enclosing living spaces, like an outdoor porch. I’ve heard of people using vinyl for greenhouses as well, but never used it myself.
Thank you 🙂 the people that have used it as part of their house, where do they live? I want to be sure if it Can stand minus 15 degrees c during wintertime?
And for how long (years) will it last the UV from the sun during the summer?
Laila.
I know of some vinyl that have a cold crack rating down to -30 F (-34 C) and are UV resistant. I’ve asked one manufacturer approximately how many years will it last in the sun before it starts to break down. I will let you know what they say. What kind of plants are you planning to grow in your greenhouse dome?
Thank you, fantastic if you want to ask a manufacturer about that. The greenhouse will be build around 70 square meters and 5-6 m high, and built so it is added to our living room in our house, so during summer and spring and autumn we can use it as one big living room, during winter it will catch the sun and give the heat to the living room ind the house. We will use it as terrace, and for growing tomatoes, cucumbers, and more exotic fruits that you normally cant grove in Denmark.
Look forward to here from you again. 🙂
They told me it will last around 5-7 years on average. This is for ClearView PVC Vinyl. It comes in 12 mil, 16 mil, and 20 mil, and is double-polished.
Did they say something about the minus degrees, what they think it Can stand?
Which Company is it? So I can get some products and maybe a small test, so I can see how clear it is.
Thank you so much for Helping me with all this:)
If you google “ClearView PVC Vinyl” you’ll get results for the product.It’s rated for -30 F.
Great. Thank you so much. I’ll give you a photo when it’ll be finished. But it will take time, we expect to do everything our self, building a straw bale House with the big green house added on the south side.
Yes, we would love to see a photo when it’s finished. Good luck!
Glass has been the traditional greenhouse covering material. The first glass greenhouse Isaw years ago was made from hundreds of glass panels.
I saw a youtube video of an old man in Nebraska using the heat stored in the earth to grow oranges. In summer he uses the 55F air from buried pipes to cool his greenhouse and in winter he uses the 55F air to warm his greenhouse. The cooling and heating is very low cost compared to using heaters or air conditioners.
I have many short pieces of discarded lumber and am exploring the possibility of using it to build a small geodesic dome. The connectors are the the big cost. Any ideas on a low cost/free connector ?
Polycarbonate is much lighter than glass, it’s far easier to fit and handle. Replacing glass sheets can be awkward, but replacing polycarbonate sheets is much easier.
The greenhouse measures a little over four feet long and four feet wide but offers over six feet of headroom inside.
Question: can you help me find material for solar cones, send a phone number and email so I can sent photo?
Want: flexible fiberglass “like” 4’ x 50’ sheet roll (makes 10) to replacement for old fiberglass Solar Cones
Damaged: 30 year fiberglass is flacking off and has to be unhealthy landing on my vegetables
Final size: 36” tall x 36” diameter with 6” hole in cone top (look like huge dog collar to protect from wound licking)
Note: My 25 Solar Cones 36” x 36” extend my growing on both ends, are very movable and more efficient than my hoop house but both are very useful
Turnips sow berry bury mulch,
Permaculture organic life time gardener
Polycarbonate is a strong thermoplastic material that is lightweight and can withstand extremely low and high temperatures.
Brad – We usually use the same pvc pipe that the greenhouse frame is made from.