Glass vs Polycarbonate Greenhouse Panels: Which Wins?
Is it better to have glass or polycarbonate in a greenhouse?
For most home gardeners, polycarbonate is the better all-around choice because it’s safer, more durable, and typically easier to install and maintain. Glass can look beautiful and deliver excellent light clarity, but it’s heavier, more breakable, and often more expensive once framing and installation needs are factored in.
Light and plant growth
Glass provides very high light transmission and stays clear for a long time if kept clean. Polycarbonate (especially twin-wall panels) still delivers strong light for vegetables, herbs, and ornamentals, but the light is slightly diffused. That diffusion can be a benefit in hot or high-sun areas because it helps reduce harsh hotspots and leaf scorch.
Insulation and temperature stability
Polycarbonate generally wins on insulation. Multiwall polycarbonate traps air between layers, helping a greenhouse hold heat longer at night and reduce temperature swings. Single-pane glass loses heat faster, which can mean higher heating costs or more reliance on thermal mass in colder seasons.
Durability, safety, and weather resistance
Polycarbonate is impact-resistant and less likely to shatter from hail, falling branches, or an accidental bump with a tool. Glass can crack or break, creating safety hazards and replacement hassles. In windy regions or areas prone to storms, polycarbonate is usually the more forgiving option.
Maintenance and longevity
Glass is naturally UV-stable, but it can be prone to algae or grime buildup, which reduces light if not cleaned. Quality polycarbonate panels include UV protection and can last many years, though cheaper panels may yellow or become brittle sooner. Keeping seals tight and panels properly fastened helps either material perform long-term.
Cost and installation
Glass structures often require sturdier framing and careful installation due to weight and breakage risk. Polycarbonate is lighter and commonly designed for quicker assembly. For a practical example of a polycarbonate setup and features like roof ventilation, see the guide here: https://splendena.com/guide-6×7-5-ft-polycarbonate-greenhouse-quick-setup-roof-vent/.
FAQ
How do I keep a greenhouse from overheating in summer?
Use roof vents, side vents, and a circulating fan to move hot air out and pull cooler air in. Shade cloth and watering in the morning can also reduce peak temperatures and plant stress.
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