The best plastic for a greenhouse depends on your budget, climate, and how long you want it to last. Most hobby and small-scale growers use 6-mil polyethylene film, which costs the least and works well for seasons or a few years. For a more permanent structure, twin-wall polycarbonate panels offer better insulation and durability, lasting 10 to 15 years or more. Here’s how each option compares so you can pick the right one for your setup.
Polyethylene Film: The Most Popular Choice
Polyethylene (PE) film is what covers the vast majority of greenhouses worldwide, from backyard hoop houses to commercial tunnels. It comes in rolls, typically ranging from 12 feet to 54 feet wide, and you cut it to the length you need. The standard thickness for greenhouse use is 6 mil (about 0.15 mm). Thinner films tear too easily, and while heavier options like 10-mil and 16-mil exist, they’re stiffer and harder to work with on curved frames.
A UV-stabilized 6-mil polyethylene film will last roughly three to four years before it starts to degrade and lose clarity. Without UV stabilization, the same film might break down in under a year. When shopping, look for films labeled “4-year” or “6-year,” which indicates the UV-resistant additives built into the plastic. The actual lifespan depends heavily on your local sun intensity. Greenhouses in the southern U.S. or other high-UV regions will wear through film faster than those in the Pacific Northwest or northern Europe.
Polyethylene film is easy to install. Most growers secure it using wiggle wire pressed into aluminum channels mounted on the greenhouse frame. This creates a tight seal without puncturing the plastic. You can also use wooden battens or snap clamps on PVC pipe frames. The affordability of PE film means replacing it every few years is still cheaper over time than investing in rigid panels, especially for larger structures.
Diffused Film vs. Clear Film
Not all polyethylene film is the same clarity, and this matters more than most growers realize. Clear film lets direct sunlight through in a straight beam, which creates bright spots on the tops of plants and deep shadows lower in the canopy. Diffused film scatters that same light in all directions as it passes through, so it reaches more leaf surfaces evenly.
The total amount of light entering the greenhouse stays the same with diffused plastic. What changes is how it’s distributed. The top of the plant gets less intense, potentially damaging light, while the lower canopy gets significantly more. This enhances photosynthesis throughout the whole plant rather than just the upper leaves. Studies have shown that diffused greenhouse film can increase crop yields by 30 to 40%, with some cases reaching as high as 85%. If you’re growing anything beyond a few tomato plants, diffused film is worth the modest price increase.
Polycarbonate Panels: The Long-Term Option
Twin-wall (or multi-wall) polycarbonate is the go-to rigid panel for permanent greenhouses. It consists of two thin sheets connected by internal ribs, creating air channels that act as insulation. This structure makes it far better at retaining heat than single-layer film, which is a major advantage in cold climates.
Polycarbonate panels transmit 85% to 90% of visible light, which is slightly less than glass but more than enough for strong plant growth. They naturally block most UV radiation, protecting plants from sunburn while still allowing the wavelengths needed for photosynthesis. The panels are virtually shatterproof, resisting hail, fallen branches, and heavy snow loads that would destroy glass or film. A quality polycarbonate panel lasts 15 to 20 years before the light transmission drops enough to warrant replacement.
The downsides are cost and condensation. Polycarbonate panels cost several times more per square foot than polyethylene film, and the framing needs to be more substantial to support rigid panels. Moisture can also build up inside the fluted channels over time if the ends aren’t sealed properly. Use foil tape or specialized end caps to keep insects and algae out of the channels.
Acrylic Panels: Maximum Light, Less Strength
Acrylic transmits up to 92% of visible light, the highest of any common greenhouse plastic. If maximizing natural light is your top priority, particularly in a low-light climate, acrylic delivers. It also holds up well aesthetically, keeping its clarity for years.
The tradeoff is durability. Acrylic is significantly less impact-resistant than polycarbonate. A hailstorm that a polycarbonate panel shrugs off could crack an acrylic one. Acrylic can also yellow over time with prolonged UV exposure, gradually reducing its light advantage. For greenhouses in sheltered locations with mild weather, acrylic works well. For anything exposed to storms, wind-blown debris, or heavy snow, polycarbonate is the safer bet.
ETFE Film: The Premium Choice
ETFE (ethylene tetrafluoroethylene) is a high-performance fluoropolymer film used in botanical gardens, commercial operations, and architectural greenhouses. It offers excellent light transmission, resists degradation from UV exposure, and has an expected service life of over 20 years. Research from the University of Arizona tested a super-durable ETFE-type film and found that 15 years of service life was a conservative estimate, with some formulations testing equivalent to at least nine years of heavy sun exposure without significant degradation.
ETFE is self-cleaning because its surface repels dirt and dust, and it’s extremely lightweight. The cost, however, puts it out of reach for most home gardeners. It’s primarily used in large-scale commercial and institutional projects where the long lifespan justifies the upfront investment.
Specialty Coatings and Additives
Modern greenhouse films often include built-in additives that go beyond basic UV stabilization. Two of the most useful are anti-drip coatings and thermal infrared barriers.
An anti-drip (or anti-condensate) coating changes how water behaves on the inside surface of the plastic. Instead of forming droplets that fall onto plants and promote fungal disease, moisture spreads into a thin, flat sheet that runs down the sides. This also improves light transmission, since water droplets scatter and block light.
Thermal infrared additives work by reducing heat loss at night. Minerals like feldspar are embedded in the film to absorb and reflect infrared radiation back into the greenhouse, acting as a mild thermal blanket. This can protect crops from frost damage and reduce heating costs in cooler months. In tropical or hot climates, the opposite technology exists: near-infrared blocking additives that reduce the amount of heat-generating radiation entering the greenhouse, lowering interior temperatures without sacrificing visible light for photosynthesis.
How UV Filtering Affects What You Grow
Most greenhouse plastics block a large portion of UV-B radiation, the same wavelengths responsible for sunburn. This is generally beneficial for plant health, but it’s not always ideal. Some crops produce higher levels of beneficial compounds when exposed to controlled amounts of UV-B. Rocket salad (arugula) grown under plastic that allowed 27% of UV-B through had significantly higher levels of health-promoting flavonoids compared to plants grown under UV-blocking film.
UV filtering also affects pollination. Bumblebees use UV light to navigate and find flowers. Greenhouses that block nearly all UV can confuse pollinators and reduce their effectiveness. If you rely on bees for pollination, choosing a film that allows some UV through, or opening vents regularly, helps keep them oriented.
Choosing the Right Plastic for Your Greenhouse
- Budget hoop house or seasonal use: 6-mil UV-stabilized polyethylene film, preferably diffused. Expect to replace it every three to four years. Standard rolls start at 12 feet wide and scale up from there.
- Year-round growing in cold climates: Twin-wall polycarbonate panels. The insulation value alone saves enough on heating to offset the higher upfront cost over time.
- Low-light climates: Acrylic panels for maximum light transmission, or clear polyethylene if you want to keep costs down.
- Large commercial operations: ETFE film or high-grade polyethylene with thermal and anti-drip additives, chosen based on local climate conditions.
- Hot climates: Polyethylene film with near-infrared blocking additives to keep interior temperatures manageable without sacrificing the light plants need.