Having the right plastic covering is essential to maximizing a greenhouse’s productivity, durability, and energy efficiency. There are different materials—polyethylene (PE), polycarbonate, PVC, EVA, and reinforced polyester (polyweave)—each with specific properties that influence light transmission, thermal insulation, UV resistance, and renovation costs. Below, we delve into their features, benefits, life cycles, and usage recommendations based on climate and crop.
Types of plastic greenhouse covering
There are generally two major types of greenhouse plastics, which are the most commonly used in greenhouses around the world. These are ethylene vinyl acetate and polyethylene.
Greenhouse plastics: Ethylene-vinyl acetate (EVA)
This is a type of coating made from copolymers of ethylene and vinyl acetate (EVA)
- Excellent light transmission
- Excellent mechanical properties
- High thermal effect
- High resistance to photodegradation
Greenhouse plastics: Polyethylene (PE)
Polyethylene is the most widely used option due to its versatility and affordable price. It is sold in single-layer or multi-layer (co-extruded) films with additives that improve UV stability, tear resistance, and light diffusion.
- Light transmission: 85–90% in single-layer films, 80–88% in multi-layer films with improved diffusion.
- Diffusion: Versions with anti-spray additives and homogeneous diffusion reduce harsh shading, promoting more uniform growth.
- Lifespan: 3–5 years in temperate climates; 2–3 years in tropical environments if enhanced UV protection is not included.
- Price: Low, with multiple thickness options (from 100 to 200 µm) and performance.
Recommended for: Short-cycle vegetable production (lettuce, chard), tunnel greenhouses, and low-cost initial projects.
Polycarbonate
Rigid polycarbonate in 4–16 mm sheets offers excellent mechanical strength and thermal insulation, ideal for fixed structures.
- Light transmission: 88–92%.
- Insulation: U-values between 1.8–3.5 W/m² K, reducing energy costs for heating and cooling.
- UV resistance: Co-extruded outer layer guarantees a 10-year lifespan without yellowing.
- Price: Medium-high, justified by its durability and low maintenance.
PVC (Polyvinyl Chloride)
PVC sheets provide flexibility and fire resistance, although they offer lower light diffusion than PE.
- Light Transmission: 80–85%.
- Durability: 5–7 years with moderate UV stability.
- Properties: Self-extinguishing and easy to weld on-site.
- Price: Medium, with intermediate installation costs.
Recommended for: Research greenhouses, ornamental nurseries, and structures where safety (fire resistance) is a priority.
EVA (Ethylene Vinyl Acetate)
EVA is a multilayer film with excellent optical clarity, adhesion, and flexibility.
- Light Transmission: 90–95%.
- Diffusion: High diffusion without loss of PAR (Photosynthetically Active) radiation.
- Lifespan: 5–6 years with UV protection.
- Price: High, justified by its light output and durability.
Recommended for: Solar greenhouses, high-value projects such as flower or pepper crops, where maximum radiation and homogeneity are critical.
Polyweave (Mesh-Reinforced Plastic)
Polyweave combines PVC or PE plastic with an internal polyester mesh that provides tear and wind resistance.
- Light Transmission: 75–85%.
- Mechanical Strength: Very high, ideal for windy areas and moderate hurricanes.
- Lifespan: 8–10 years.
- Price: High, but offers excellent return on investment in extreme climates.
Recommended for: Greenhouses in regions with strong winds, moderate cyclones, or for long-term projects requiring maximum reliability.
Selection Criteria and Best Practices
- Light Transmission and Diffusion: Adjust the material to the type of crop; leafy crops prefer high diffusion, while floral crops require maintaining PAR.
- UV resistance and climate cycling: In tropical areas, prioritize multi-layer films with reinforced UV stabilizers.
- Total cost of ownership: Consider not only the initial cost but also the useful life and energy savings (polycarbonate and EVA).
- Installation and tilt: Maintain a 5–10% angle to avoid water and dirt accumulation; test for proper tension to prevent sagging.
- Maintenance: Clean annually with water and mild detergent; check hardware and anchors every 6 months.
Choosing the right plastic for your greenhouse is vital to maximize light, thermal control, and the longevity of your cover. At J. Huete Greenhouses, we are greenhouse experts and can help you select the optimal plastic solution for your climate, crop, and budget.
Request personalized advice and discover how to maximize the performance and durability of your greenhouse.
