What is the Best Plastic for a Greenhouse?

A photo of a small hooped greenhouse covered with polyethylene plastic in the fall
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You have your greenhouse structure picked out, but wait… what’s the best plastic for a greenhouse? Polyethylene or polycarbonate? 6 mil or 10 mil? Clear or opaque? There are SO many options out there and it’s easy to get overwhelmed. I’m here to help!

While I’m not a big fan of plastic in general, it does make an excellent choice for greenhouse growing. It is inexpensive and light-weight compared to glass and flexible, allowing you to mold it to rounded structures. 

However, not all plastic is created equal! Picking the right one for your set-up and goals is critical. I’m confident that by the end of this article, you’ll know exactly which one is the best plastic for your greenhouse.

Features of the Best Plastic for a Greenhouse

Before you throw any old plastic into your shopping cart, there are a few key things that you need to consider first. Weather conditions, greenhouse structure, budget constraints and plant needs are all going to impact what you should buy.

Material

Polyethylene Plastic

Polyethylene plastic is the most common material used to cover a greenhouse and what I personally use. It’s inexpensive, flexible, and can last up to 4 years. A double layer can even be used for extra insulation.

Polyethylene plastic spread over a small greenhouse with lettuce growing in it

It comes in different thicknesses from 1/2 mil to 12 mil, but 6-10 mil is ideal for a greenhouse or high tunnel. The higher the number, the thicker it is (while also letting less light through). I personally use 6 mil.

Lastly, polyethylene plastic comes in two grades: greenhouse grade and utility grade (what you’ll find at your hardware store). Utility grade is certainly more readily available and cheaper, but it might not last more than a year or two.

Polyethylene plastic is ideal if you have:
  • A hoop style structure that needs a flexible covering. 
  • Mild-Moderate weather conditions
  • A temporary structure that don’t need to be covered all year round
  • A small budget

Polycarbonate 

Polycarbonate is another common covering, however it’s rigid in nature and quite a bit more expensive. The benefits of polycarbonate is that it has great light transmission and it lasts quite a bit longer than polyethylene plastic (up to 10 years). It’s also shatter-proof and much lighter than glass. A great option for a permanent structure.

A greenhouse covered with polycarbonate plastic sheeting

Polycarbonate plastic is ideal if you have:
  • A permanent structure that will be covered all year round
  • A structure with straight sides or mild curves
  • Extreme weather conditions (heavy snow, high winds)
  • A larger budget

Woven Plastic

Woven plastic takes basic polyethylene plastic to a whole new level. It features woven, thin strips of polyethylene plastic in a grid pattern that results in a product that is 15x stronger than regular polyethylene plastic. Light transmission is still excellent at 88%.

Woven plastic for greenhouse - close up view

The negative is that it can be quite expensive. However, if you have extreme weather conditions such as heavy snow or high winds, it will pay off in the long-run.

Woven plastic is ideal if you have:
  • A hoop style structure that needs a flexible covering. 
  • Extreme weather conditions (heavy snow, high winds)
  • A moderate budget

Reinforced Polyfilm

This is similar to woven plastic in terms of functionality, but it is constructed with 3-ply laminate combining two layers of linear, low density polyethylene and a high strength cord grid. Another great (but expensive) option for a high-strength, flexible covering that resists tearing.

Reinforced polyfilm material for greenhouse - a closeup view

Reinforced polyfilm is ideal if you have:
  • A hoop style structure that needs a flexible covering. 
  • Extreme weather conditions (heavy snow, high winds)
  • A larger budget

Thickness

If you’ve decided to use polyethylene plastic, you’ll notice that it comes in a lot of different thickness options. What you choose depends on your plant needs and weather conditions. 

  • 4 mil: Don’t waste your time. It will shred to pieces by the end of 1 season.
  • 6 mil: Inexpensive, relatively strong and has a 90% light transmittance per layer. This is the thickness I personally use because it holds up to our Minnesota winters, but I don’t need it to last year after year because I take it down once summer hits. 
  • 8 mil: Stronger than 6 mil while still providing good light transmittance of 90%. A great option if you want it to last several years or if you have extreme weather conditions.
  • 10 mil: Light transmittance dips to 85% now with the thicker weight and is more pricey, but also much stronger if you’re worried about durability. At this thickness, the plastic is more tarp-like.
  • 12 mil: Overkill for most applications. Has a strength breakpoint of 65 lbs per square inch. Light transmittance of 82%.

Transparency

Greenhouse plastic comes in clear, opaque and even white, but what should you choose?

Clear

Clear is the best choice for most gardeners because it lets in the most light. This is especially helpful if you’re using your greenhouse in the early spring or late fall where sunlight is at a minimum. This is the type that I use.

Opaque

Opaque greenhouse plastic filters the light a bit, which can be beneficial in warm climates or during the summer months to avoid baking your plants. Shade cloth can also be used for additional light filtering. 

White

White filters light at 55%, which is quite significant and has limited applicability. This is typically not used in most circumstances.

Size 

Greenhouse plastic comes in a wide variety of sizes, which is great because greenhouses do too! However, you’re definitely not going to want to buy a roll that’s 150′ long if you have a small greenhouse. The key is figuring out the right size that will span your greenhouse in one piece. If you’re using multiple pieces, you will have more seams and you’ll likely end up with rips and tears.

To determine the size that you need, measure out the length and width of your greenhouse surfaces and add a few extra feet to be safe.

A high tunnel in front of a true greenhouse

Other Greenhouse Plastic Features

You thought material, thickness and size was the only thing to consider? Guess again! There are even more features that we need to discuss before you’re ready to make your product decision.

Anti-drip & anti-dust properties

Anti-drip properties reduce surface tension on the greenhouse plastic, causing water droplets to flatten and run down the sides instead of onto the plants. This is beneficial to reduce the risk of plant disease or burning of the leaves. This feature can reduce light transmission by 3-8%.

Anti-dust properties reduce the electrical charge on the surface and are especially helpful if you plan to use your covering year-after-year. Dust collecting on greenhouse plastic is not only unsightly, but it reduces overall light transmission.

Infrared tint

Sometimes an infrared tint is added to greenhouse plastic to reduce heat loss, which is idea for those in cold weather climates.

Double layer

If you live in a cold climate, then double layer greenhouse plastic might be worth looking into! With a double layer, this provides extra insulation and can make a big difference on those cold nights. Light transmission is a bit lower than single layer.

UV protection

Greenhouse plastic that offers UV protection blocks UV rays, which can reduce the impact of certain pests like aphids, thrips and whiteflies. However, if you are using bees for pollination, this might not be ideal. Bees need UV light to locate flowers.

Don’t worry, it doesn’t block out all light! The rays that the plants need for photosynthesis won’t be impacted. UV protection also increases the lifespan of the plastic.

Photoselective

Some types of greenhouse plastic may offer a tint to it (like red), which is preferred by certain types of plants. 

The Best Plastic for a Greenhouse (Top 5 on the market!)

Alright, we’ve made it! It’s time to jump into the good stuff. I scoured the internet for you and here are 5 best greenhouse plastic products out there.

Pick #1: Farm Plastic Supply 6 mil Polyethylene (Budget friendly)

High-quality polyethylene plastic sheeting that is made specifically for greenhouses (this is not your flimsy utility grade plastic!). Includes UV protection to prolong the life of your greenhouse plastic and provides 90% light transmission. The rolls come in many sizes from widths of 10′ to 60′ and lengths of 24′ to 80,’ making it highly customizable to your greenhouse structure.

The Homesteading RD's Product Picks:

This is the best all-around choice for most homesteaders.
-Lifespan: 4 years

-Light transmittance: 90%

-Features: UV protection

Pick #2: Bootstrap Farmer 6 mil Polyethylene (Best quality)

This is the real-deal greenhouse plastic straight from Bootstrap Farmer. Available in larger sizes than the product above, making it a great option for those with large green houses. Available in widths of 16′ to 54′ and lengths of 30′ to 150.’ Features 5-layer film technology for added strength and longevity along with a 4-year rating and warranty against UV degradation.

The Homesteading RD's Product Picks:

This is the best all-around choice for large greenhouses, or for those wanting to avoid Amazon.

-Lifespan: 4 years
-Light transmittance: 90%
-Features: UV protection, anti-dust

Pick #3: Bootstrap Farmer 6 mil High Diffusion Film (Most features)

If you’re looking for the best of the best when it comes to features, this high diffusion film from Bootstrap Farmer definitely delivers. Want anti-drip? No problem. Want IR properties to keep the temps up in the winter? You’ve got it. Want a little UVA light to come through so that the bees can do their job? It does that, too!

The Homesteading RD's Product Picks:

Looking for all of the features? This one has it all!

-Lifespan: 4 years

-Light transmittance: 88%
-Features: Anti-dust, anti-drip, high light diffusion, UVA inclusion (best for the bees!), Infra-red properties (keeps heat in)

Pick #4: Bootstrap Farmer 8 mil Woven Plastic (Extreme weather & pests)

This is a premier option if you have severe weather like heavy snow or high winds. The woven design makes this covering 15x stronger than regular greenhouse plastic! Made from coated poly with UV additives for extra protection. Also features light diffusion, which can reduce pest pressure from pests like aphids, thrips and white flies.

The Homesteading RD's Product Picks:

Do you have crazy weather and need a sturdy option? This is for you!

-Lifespan: 4 years

-Light transmittance: 88%
-Features: Anti-fog, UV protection, enhanced light diffusion (pest resistance), 15x stronger than regular plastic

Pick #5: 4mm Polycarbonate Panel (Long-lasting solution)

Looking for a more permanent covering that you don’t have to replace every few years? Then investing in polycarbonate panels would be a great choice for you. These 4 mm panels are nearly indestructible and lasts 10 years (sometimes longer!). Features twin wall construction that provides good insulating value. 

The Homesteading RD's Product Picks:

This is an excellent choice for durable, permanent structures

-Lifespan: 10 years

-Light transmittance: N/A

-Features: UV protection

FAQ About Greenhouse Plastic:

How much plastic do I need for my greenhouse?

Greenhouse plastic comes in a wide variety of sizes, which is great because greenhouses do too! However, you’re definitely not going to want to buy a roll that’s 150′ long if you have a small greenhouse. The key is figuring out the right size that will span your greenhouse in one piece. If you’re using multiple pieces, it won’t weather well.

To determine the size that you need, measure out the length and width of your greenhouse surfaces and add a few extra feet to be safe.

Can I reuse greenhouse plastic?

Absolutely! If you plan to keep your greenhouse plastic on your structure year-round, it only needs to be replaced once it rips or tears. Some materials like polycarbonate can last up to 10 years!

If you take it down for the summer (like I do), feel free to use it again as long as it is in good shape. If you’re able to secure it with clips or furring strips, you’ll likely be able to save it year after year. If you’re securing it with staples, it likely won’t last for another season.

How do you clean greenhouse plastic?

Often, a simple rinsing with the garden house will do the trick. For stubborn spots, try a little dish soap mixed in warm water with a soft rag. Avoid using anything with grit or a pressure washer as this might puncture your greenhouse plastic.

How long does greenhouse plastic last?

It totally depends on the material that you’ve chosen, how you’ve secured it, UV intensity and your weather conditions. In general, this is how long each material will last if properly cared for.

  • Polyethylene plastic: 2-4 years
  • Polycarbonate: 10 years
  • Woven plastic: 4 years (6 years if covered with 6 mil polyethylene plastic)
  • Reinforced polyfilm: N/A

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Final Thoughts

Picking out the perfect greenhouse plastic can be a headache with all of the options that are available to us today. It’s a blessing and curse! However, I’m hopeful that now you know exactly what you need and how to find it. Happy gardening!

*Information in this article was referenced from personal experience and/or from my favorite winter gardening book The Year-Round Vegetable Gardener unless otherwise noted.

The Homesteading RD's Product Picks:

This is an excellent gardening book to have on hand if you live in a cold climate like me! She provides great tips on how to construct and use cold frames/mini tunnels, plan succession harvests, you name it!

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12 thoughts on “What is the Best Plastic for a Greenhouse?”

  1. Thank you for your thoughts on this. We are just planning to build a greenhouse, and thinking that we might use polycarbonate, for the reasons you listed. I don’t think glass would be a great idea for our greenhouse, but I want to build something that will last a reasonable time without degrading in our harsh UV light here in New Zealand. Polycarbonate seems the best choice.
    Thanks again, I really enjoyed this article.

  2. Thanks for the breakdown! We’re hoping to build a plastic-wrapped greenhouse in the near future, and I had thought the thicker plastic might be best. Seems like the 6mil Farm Plastic might be the better bet for us in Georgia, though.

  3. Incredibly detailed and useful information! We used polycarbonate panels growing up, and I’ve been thinking how I would do it differently for my own. Thank you!

  4. We have been thinking about putting in a green house for cuttings, coffee plants, and winter greens. Thank you for the information! It definitely doesn’t seem as bad now.

  5. We have a kind of woven plastic with some internal reinforcement now. It works pretty well so far! We don’t have a huge snow load but we do get ice, which is bothersome. We haven’t had any tears, though. We don’t grow in our greenhouse – it’s super tiny – but we do overwinter and protect cuttings and seedlings. The light penetration has been great and kept everything alive really well.

    This is a great article, by the way – very simple but thorough!

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