Key Takeaways -

• Choosing the right greenhouse plastic ensures durability, insulation, and optimal growth.
• UV protection, thickness, and light transmission affect the ideal environment for plants.
• Polyethylene is budget-friendly, while polycarbonate offers long-term durability.
• Matching plastic to your climate and structure extends its lifespan and efficiency.

Greenhouse plastic is essential for protecting plants, but choosing the right type can make a big difference. The right plastic helps control temperature, light, and durability, especially in the UK’s changing weather.

This guide will explain what to look for when selecting greenhouse plastic, including UV protection, insulation, and weather resistance. It will also compare different types to help you find the best option for your needs.

Keep reading to learn how to choose the best plastic for your greenhouse. Whether you need a temporary cover or a long-term solution, the right choice will keep your plants healthy and your greenhouse lasting longer.

The Importance of Choosing the Right Greenhouse Plastic

How the Right Plastic Affects Your Greenhouse

The type of plastic you choose directly impacts plant growth, temperature control, and overall efficiency. High-quality plastic allows the right amount of sunlight while maintaining warmth, helping plants thrive year-round (1).

In the UK, where weather conditions can be unpredictable, durable and well-insulated plastic is essential. It protects against cold temperatures, strong winds, and heavy rain, ensuring your greenhouse remains stable and effective.

Investing in the right material reduces the need for frequent replacements, saving both time and money in the long run.

Key Considerations Before Your Purchase

Choosing the right greenhouse plastic is essential for plant health, durability, and long-term efficiency. Here are the key factors to keep in mind:

• Light Transmission & Light Diffusion: Plants need the right balance of sunlight. Clear plastic allows maximum light, ideal for winter, while diffused plastic spreads light evenly to prevent plant burn.
• UV Resistance & Lifespan: Sun exposure can cause plastic to degrade. UV-resistant plastic prevents brittleness and yellowing, extending its lifespan and reducing replacement costs.
• Insulation & Temperature Control: Insulated plastics, like twin-wall polycarbonate, help maintain a stable temperature, keeping plants warm in winter and cool in summer.
• Strength Against Weather: Wind, rain, and snow can damage weak plastic. Reinforced or thicker materials offer better protection, reducing the risk of tears and extending durability.

Comparing the Different Types of Greenhouse Plastic

Polyethylene (PE) Plastic

Polyethylene is one of the most common and affordable choices for greenhouse coverings. It is highly flexible, making it ideal for hoop-style or temporary structures. Available in various thicknesses, with 6-10 mil being the most effective, it provides a balance between durability and cost.

UV-stabilised versions can last up to four years, and double-layered options improve insulation. However, it has a shorter lifespan than rigid plastics and can degrade with prolonged exposure to UV rays. Regular maintenance and replacement are necessary.

It is best suited for temporary greenhouses or budget-conscious gardeners looking for an easy-to-install solution.

Polycarbonate Panels

Polycarbonate panels offer excellent durability and insulation, lasting 10-20 years with proper care. They are 200 times stronger than glass, making them highly impact-resistant. Their ability to diffuse light evenly and provide superior insulation makes them a great option for year-round growing.

Twin-wall polycarbonate traps warm air, reducing heating costs in colder months. However, they are more expensive than polyethene, though still a cost-effective alternative to glass. Over time, polycarbonate may lose transparency and require occasional cleaning.

This material is best for permanent greenhouse structures and areas with extreme weather conditions, including strong winds and heavy snowfall.

Polyvinyl Chloride (PVC) Plastic

PVC plastic is stronger and more UV-resistant than polyethene, making it a durable option for a greenhouse covering. It is naturally mildew-resistant, making it ideal for humid environments where mould could be an issue. PVC is also easy to work with and lasts longer than polyethene.

However, it is more expensive and can degrade over time without UV stabilisation. Despite this, it remains a solid choice for growers looking for a mid-range option. It is best for greenhouses exposed to fluctuating temperatures, where a balance between durability and affordability is required.

Woven & Reinforced Polyfilm

Woven and reinforced polyfilm is designed to withstand extreme weather conditions, providing extra strength against wind, snow, and tearing. It offers a good balance of flexibility and durability, making it a reliable choice for long-term use.

While it is more expensive than standard polyethene, its resistance to harsh conditions makes it a worthwhile investment. This type of plastic is ideal for hoop-style structures that require a flexible but sturdy covering.

It is especially suited for high-wind or heavy-snowfall areas where standard plastic may not provide adequate protection.

Acrylic (Perspex) Sheets

Acrylic sheets are a lightweight, durable alternative to glass, offering excellent light transmission and much stronger. They provide excellent clarity and impact resistance, making them up to 20 times stronger than traditional glass panels.

This makes them a good option for growers who prioritise maximum light exposure. However, they do not insulate as well as polycarbonate and are slightly more expensive than polyethene.

Acrylic sheets are best for aesthetically pleasing greenhouses or growers who want to balance durability and high light transmission. They are ideal for structures where appearance and maximum sunlight are top priorities.

Choosing the Right Features for Your Greenhouse

Thickness & Durability: How Thick Should Your Plastic Be?

The thickness of your greenhouse plastic affects durability and insulation. A 4 mil sheet is too thin and prone to tearing. A 6 mil thickness is standard, balancing cost and strength. For better protection, 8-12 mil plastic lasts longer but slightly reduces light transmission.

Your choice depends on the climate and how long you need the covering to last.

How Much Light Does Your Greenhouse Need?

Clear plastic allows maximum sunlight, which is ideal for UK winters. Opaque plastic reduces light intensity, preventing overheating. White plastic blocks 45% of sunlight, which is useful for shading in hot conditions. The best option depends on your climate and plant needs.

UV Light Protection: Extending the Life of Your Plastic

Sunlight weakens plastic over time. UV-treated plastic resists damage, extending lifespan and reducing replacements. Some UV coatings also deter pests. Investing in UV protection ensures durability and optimal growing conditions.

Temperature & Insulation: Keeping Your Greenhouse Warm

Infrared (IR) coatings trap heat, ideal for colder months. Double-layer plastic improves insulation but slightly reduces light. These features regulate temperature, reducing heating costs and protecting plants from sudden drops.

Reducing Condensation & Dirt Build-Up

Condensation leads to mould, while dirt reduces light transmission. Anti-drip coatings prevent water droplets from forming, keeping plants dry. Anti-dust coatings reduce buildup, maintaining clear plastic and minimising cleaning.

How to Pick the Best Plastic for Your Needs

What Works Best for Your Greenhouse Structure?

Your greenhouse design determines the best plastic. Hoop houses and tunnels need flexible polyethene or woven plastic. Permanent greenhouses benefit from durable polycarbonate or PVC panels. Cold frames work best with polycarbonate sheets for insulation.

Choosing the right material keeps your structure stable and efficient.

Matching Your Plastic to UK Weather Conditions

UK weather varies, so the right plastic is key. Mild climates suit 6-8 mil UV-treated polyethylene. Cold winters require twin-wall polycarbonate for insulation. High-wind or snowy areas need woven or reinforced plastic for durability. Weather-appropriate plastic ensures a stable growing environment.

Balancing Quality with Budget

Budget impacts your choice. Low-cost 6 mil polyethylene works short-term. Mid-range woven polyethene or PVC offers durability. High-budget polycarbonate panels provide insulation and last longer. The right balance ensures cost-effectiveness and plant protection.

Frequently Asked Questions

How Do I Know If I Need to Use a Shade Cloth?

A shade cloth is useful if your greenhouse gets too hot or if plants show signs of sunburn, such as wilting or leaf discolouration. It helps regulate temperature by reducing excessive sunlight while still allowing enough light for growth.

If you grow heat-sensitive plants or live in an area with strong summer sun, a shade cloth can prevent overheating and improve plant health.

How Long Does Greenhouse Plastic Last?

The lifespan of greenhouse plastic depends on the material and environmental conditions. Standard polyethene lasts 2-4 years, while UV-stabilized or reinforced plastic can last up to 6 years. Polycarbonate panels, a more durable option, can last 10-20 years with proper maintenance.

Regular cleaning and protection from harsh weather can help extend its lifespan.

Can I Reuse Greenhouse Plastic?

Yes, greenhouse plastic can be reused if it remains in good condition without major tears or UV damage. Carefully remove and store it in a dry, shaded area when not in use to prevent deterioration. If the plastic has small tears, repair tape can extend its life for another season.

However, heavily damaged or brittle plastic should be replaced.

What’s the Best Way to Clean Greenhouse Plastic?

To clean greenhouse plastic, use mild soap and warm water with a soft sponge or cloth. Avoid harsh chemicals or abrasive brushes, as they can weaken the plastic or remove protective coatings. Rinse thoroughly with clean water and allow it to dry to prevent dirt buildup.

Regular cleaning improves light transmission and extends the lifespan of the plastic.

How Do I Prevent Greenhouse Plastic From Turning Yellow or Brittle?

UV exposure is the main cause of greenhouse plastic becoming yellow or brittle over time. Choosing UV-stabilised plastic helps prevent this issue and extends its lifespan. Regular cleaning removes dirt and chemicals that can accelerate degradation.

If your plastic is ageing, consider using a shade cloth or applying a UV-protective spray to reduce further damage.

Conclusion

Choosing the right greenhouse plastic is essential for creating an ideal environment that supports healthy plants and long-term durability. Factors like light transmission, UV protection, insulation, and weather resistance all play a role in ensuring optimal growth.

By selecting the best material for your structure, climate, and budget, you can maximise efficiency and extend the lifespan of your greenhouse covering. Investing in quality plastic will protect your plants, improve energy efficiency, and provide a stable growing space for years.

Sources -

1. https://www.theplasticpeople.co.uk/blog/building-a-greenhouse/