Guide to Greenhouse Materials for Maximizing Crop Yields

In modern agricultural production, greenhouses play a vital role by providing crops with a controlled growing environment that protects them from harsh weather conditions and pests. However, successful greenhouse operation depends not only on advanced internal equipment but crucially on the materials used in construction. Many growers focus primarily on interior systems while neglecting the structural components, which can lead to premature aging of the structure or reduced crop yield and quality. Whether building a custom greenhouse or selecting a prefabricated kit, choosing high-quality materials is paramount—they extend the structure's lifespan and create superior growing conditions for healthier, more robust plants.

With numerous greenhouse types available, growers often face confusion when selecting materials. This article addresses five key questions about greenhouse materials to help growers make informed decisions before construction begins.

Greenhouse covering materials, also called cladding, significantly impact performance. The three primary options—polycarbonate, film, and glass—each have distinct advantages and disadvantages, though polycarbonate generally offers the best long-term benefits for plant growth.

• Polycarbonate: This synthetic resin offers high strength, excellent light transmission, and superior weather resistance. Twin-wall polycarbonate (two layers with an air gap) provides enhanced insulation:
  • Superior insulation: High R-values maintain stable temperatures and reduce energy costs
  • Optimal light diffusion: Excellent light transmission and scattering promote plant growth
  • Durability: Impact-resistant (hundreds of times stronger than glass) and lasts 10+ years
• Film: Typically polyethylene or PVC, this low-cost option has advantages:
  • Affordable for budget-conscious growers
  • Lightweight and easy to install
  • Good initial light transmission
  But significant drawbacks include:
  • Poor insulation requiring supplemental heating
  • Short lifespan (1-3 years before replacement)
  • Vulnerability to wind damage
• Glass: The traditional choice offers:
  • Exceptional light transmission
  • Long-term durability
  • Aesthetic appeal
  But comes with challenges:
  • High cost for materials and installation
  • Heavy weight requiring robust framing
  • Fragility against hail and storms
  • Moderate insulation requiring additional measures

For growers prioritizing long-term value and crop quality, polycarbonate—especially twin-wall panels—represents the optimal choice.

Galvanized steel, coated with zinc through electrochemical or chemical processes, provides exceptional corrosion resistance. The zinc layer protects against rust, with the zinc corroding preferentially if scratched—extending the structure's lifespan.

As greenhouse framing material, galvanized steel offers:

• Superior corrosion resistance for humid environments
• High strength to withstand wind and snow loads
• 20+ year lifespan with minimal maintenance
• Ease of fabrication (cutting, welding, drilling)

Two primary types exist: hot-dipped (thicker zinc coating, better protection) and electro-galvanized (thinner coating). Hot-dipped galvanized steel is recommended for greenhouse frames. While aluminum offers lighter weight and corrosion resistance, its lower strength and higher cost make galvanized steel the preferred choice for most applications.

Often overlooked, greenhouse flooring significantly impacts functionality and plant health. Proper flooring ensures good drainage, weed prevention, and easy maintenance. The two main options present different advantages:

• Concrete:
  • Easy cleaning and sanitation
  • Smooth surface for equipment movement
  • Properly designed for excellent drainage
  • Long lifespan with low maintenance
  Drawbacks include higher cost and potential water pooling if drainage isn't properly designed.
• Gravel:
  • Low-cost option
  • Simple installation
  • Natural drainage properties
  • Weed suppression when combined with landscape fabric
  Disadvantages include difficulty cleaning, potential for microbial growth, and uneven surfaces.

The choice depends on budget, crop type, and drainage requirements. Alternative options like permeable pavers or wood chips may also be considered.

Maintaining optimal temperatures requires careful heating system selection to balance plant needs with energy efficiency. Primary options include:

• Air heating: Fast warm-up using fuel/gas or electric heaters, but creates uneven temperature distribution
• Hydronic heating: Even heat distribution via hot water pipes (radiators or floor systems), though slower response and higher installation cost
• Geothermal: Sustainable but location-dependent with high initial investment
• Solar: Environmentally friendly but requires supplemental storage for cloudy periods

Supplementary measures enhance efficiency:

• High R-value cladding materials
• Thermal curtains to reduce heat loss
• Ensuring tight seals around doors and vents

A greenhouse's longevity depends on material quality, structural design, climate conditions, and maintenance. With proper selection and care, structures can last decades:

• Polycarbonate: 10+ years with regular cleaning and UV protection
• Galvanized steel: 20+ years with periodic inspections and rust prevention
• Concrete floors: Decades with proper maintenance and crack repair

Structural design should account for local conditions—reinforced framing for windy or snowy areas, for example. By selecting quality materials, implementing sound design, and performing regular maintenance, growers can ensure stable, long-term greenhouse performance for optimal crop production.