How to Choose Greenhouse Plastic Film

Selecting the right plastic film for your greenhouse is important because it affects everything from the durability of the structure to the climate inside the greenhouse. Here are the key factors to consider when choosing a plastic film:

1. Type of Plastic Film

• Polyethylene (PE): The most common type of greenhouse plastic. It’s affordable, provides good light transmission, and is flexible. There are single or double layers of polyethylene, with the double layer offering better insulation.
• Polycarbonate: More expensive than polyethylene, polycarbonate panels (either twin-wall or triple-wall) are more durable and provide better insulation but can be harder to install and are less flexible.
• Polyvinyl Chloride (PVC): Less commonly used for greenhouses, PVC film is durable but tends to be heavier and not as commonly preferred for larger greenhouses.

Clear Poly film used for agriculture tunnels

2. UV Protection

• UV protection is crucial because it extends the life of the plastic film and protects plants from harmful ultraviolet rays. Most high-quality greenhouse film plastics have UV inhibitors added during manufacturing.
• Consider:
  • UV Resistance: Look for plastics that provide 3-5 years of UV protection if your climate has intense sun.
  • Anti-Condensation Coatings: If you have high humidity or condensation issues, choose a film with a built-in anti-condensation layer to minimize water droplets that can block light.

UV resistant poly film used for nursery greenhouse

3. Thickness (Mil or Gauge)

• Thickness affects the durability and insulation properties. In greenhouse plastic, thickness is typically measured in mil (thousandths of an inch) or gauge.
  • Single Layer Film: Usually ranges from 6 mil to 10 mil thick. Thicker film provides better protection but can reduce light transmission.
  • Double Layer Film: These films are typically about 4-6 mil thick but can be inflated to create an insulating air gap between the layers.
• Thicker films are more resistant to wear and tear but may limit light transmission slightly.

4. Light Transmission

• For optimal plant growth, you want a plastic film that allows good sunlight to penetrate the greenhouse. Most greenhouse plastics allow between 80-90% light transmission.
  • Clear Films: These allow the most light through.
  • Diffused Greenhouse Films: They scatter light more evenly inside the greenhouse, which helps to reduce shadowing and improves growth by distributing light more uniformly.

Diffused film used for blueberry growing

5. Insulation (R-Value)

• If you are in a colder climate, insulation is important for temperature control. Double-layer polyethylene film with air between the layers can offer much better insulation (higher R-value) than single-layer film, helping to retain heat.
• Double-Layer vs. Single-Layer: Double-layer films are more common for colder climates because they help with heat retention during the winter months.

Tunnel film for blueberry growing

6. Durability and Warranty

• Greenhouse plastic can experience wear due to wind, rain, snow, and UV exposure, so look for a plastic that offers good durability.
• Many high-quality greenhouse films come with warranties that promise protection against UV degradation, tearing, and other weather damage for a specified number of years (typically 3-5 years).
• Some films have anti-fog coatings, anti-dust coatings, or are made with puncture-resistant material for enhanced longevity.

7. Wind and Weather Resistance

• In areas with high winds, you’ll need a stronger, more durable plastic film that can handle these conditions. Reinforced polyethylene films with woven fabric in them can offer additional strength.
• Make sure the film is rated for your specific climate conditions (e.g., wind, snow, and extreme temperatures).

8. Cost

• Polyethylene films are generally the most affordable option, while polycarbonate is more expensive but also lasts longer and provides better insulation. Balance your budget with your specific needs.
• Consider the lifespan and durability of the film; while polycarbonate might be more expensive upfront, it may save money in the long run if you’re in a harsh climate.

9. Ease of Installation

• Some plastics (like polyethylene) are more flexible and easier to install than polycarbonate panels. Consider the ease of handling and installing the plastic film when selecting the material.

Summary:

• For warmer climates: Polyethylene with UV protection and a light diffusion coating is generally sufficient.
• For colder climates: A double-layer film with air between the layers will help with insulation. Consider a thicker film with better puncture resistance.
• For durability: Reinforced polyethylene or polycarbonate offers more longevity and better protection from the elements.