Is polycarbonate or glass better for a greenhouse?

For most home growers, polycarbonate is better. Twin-wall polycarbonate insulates far better than single-pane glass thanks to the air gap between its walls, it's nearly unbreakable and hail-resistant, it's lightweight, and it diffuses light so plants don't scorch. Glass wins on absolute clarity and lifespan, but it's heavier, more expensive, and can shatter.

Does polycarbonate let in as much light as glass?

Clear single-wall polycarbonate transmits roughly 90% of light — close to glass's ~90–92%. Twin-wall polycarbonate transmits a bit less (around 80%) but diffuses it evenly, which actually reduces scorching and shaded spots. For plant growth, twin-wall's diffused light is often more useful than glass's direct light.

How long does a polycarbonate greenhouse last?

Quality UV-protected polycarbonate panels typically last 10 to 15 years or more before they begin to yellow, and premium panels carry warranties in that range. Cheap, non-UV-stabilized panels can yellow and grow brittle in just a few years. Glass, by contrast, can last decades if it isn't broken.

Is a glass greenhouse worth the extra cost?

A glass greenhouse is worth it if you want the clearest view, a traditional look, and a structure that can last decades — and you're willing to pay more, deal with the weight, and accept the shatter risk. For pure growing performance, frost protection, and value, twin-wall polycarbonate is the smarter buy for most people.

Polycarbonate vs Glass Greenhouse 2026: Which Should You Buy?

Quick Answer: For most home growers, a polycarbonate greenhouse is the better buy. Twin-wall polycarbonate insulates far better than single-pane glass, it’s nearly unbreakable and hail-resistant, it’s lightweight, and it diffuses light evenly so plants don’t scorch. Glass wins on absolute clarity, a traditional look, and decades-long lifespan — but it costs more, is heavy, and shatters. Choose polycarbonate for four-season growing and value; choose glass for looks and longevity if budget isn’t the constraint.

Glazing is the single biggest decision when buying a greenhouse — it drives how warm the structure stays, how much light your plants get, how long it lasts, and how much it costs. Here’s how polycarbonate and glass actually compare, factor by factor.

Polycarbonate vs glass at a glance

Factor	Polycarbonate (twin-wall)	Glass
Light transmission	~80% diffused (clear PC ~90%)	~90–92% direct
Insulation	Excellent (air gap between walls)	Poor (single pane)
Durability	Nearly unbreakable, hail-resistant	Can shatter
Weight	Light — easy DIY assembly	Heavy — needs a strong frame/base
Lifespan	~10–15+ yrs (UV-protected)	Decades if unbroken
Cost	Lower	Higher
Best for	Growing, frost protection, value	Clarity, looks, longevity

Light transmission

Glass is the clarity champion, transmitting around 90–92% of light directly. Clear single-wall polycarbonate is close behind at roughly 90%. Twin-wall polycarbonate transmits a bit less — around 80% — but it diffuses that light, scattering it evenly through the greenhouse. For plants, diffused light is often the winner: it reaches lower leaves and shaded corners, and it reduces the hot spots and scorching that direct glass light can cause on a bright day. If you’re growing in a cool, cloudy climate and want maximum brightness, clear polycarbonate or glass edges ahead; for balanced, scorch-free growth, twin-wall is excellent.

Insulation and heat retention

This is where polycarbonate pulls clearly ahead. Twin-wall (and triple-wall) polycarbonate has an air gap between its layers that acts like double glazing, holding overnight warmth far better than a single pane of glass. Premium panels like the 10mm twin-wall used in heavy-duty kits are genuinely insulating. That means lower heating bills and better frost protection — the difference between a three-season and a four-season greenhouse. Single-pane glass loses heat fast and needs more supplemental heating to hold the same temperature.

Durability and safety

Polycarbonate is nearly unbreakable and hail-resistant — a big deal if you get storms, have kids or pets, or live somewhere windy. Glass shatters, and a broken pane is both a replacement cost and a safety hazard (shards near a garden bed). Polycarbonate can scratch and, if it’s not UV-stabilized, yellow over time — but quality UV-protected panels resist that for a decade or more. For most real-world backyards, polycarbonate’s toughness is the deciding factor.

Weight, assembly, and cost

Polycarbonate is light, which makes DIY kit assembly manageable for one or two people and lets the structure sit on a lighter frame and base. Glass is heavy, demands a robust frame and a level, solid foundation, and is harder (and riskier) to install. Polycarbonate kits also cost less up front. Glass costs more to buy, more to ship, and more to build.

Lifespan

Here glass claws some ground back. A glass pane can last decades if it’s never broken, while polycarbonate has a finite life — quality UV-protected panels run 10–15 years or more before they start to yellow, and cheap non-UV panels can degrade in just a few. If you want a structure to outlive you and you’ll protect it from impact, glass is the long-game material. For most buyers, though, a 10–15 year panel life is plenty.

Our top polycarbonate pick

Palram Canopia Hybrid

Best polycarbonate greenhouse kit · ~$450–800

Unbreakable twin-wall polycarbonate roof plus clear side panels (over 90% light).
Rust-proof aluminum frame, galvanized steel base, and a built-in rain gutter.
Named Better Homes & Gardens' Best Overall Greenhouse Kit.
Available in 6x4, 6x8, and 6x10 sizes.

Check price on Amazon →

If the comparison points you toward polycarbonate — as it does for most growers — the Palram Canopia Hybrid is our overall best greenhouse kit pick. It combines a durable twin-wall roof with bright clear walls, giving you the best of both light and insulation.

The bottom line

Choose polycarbonate — ideally twin-wall — if you want better insulation, near-unbreakable durability, lighter assembly, and a lower price. It’s the right glazing for four-season growing, frost protection, and value, which is why it’s what we recommend to most buyers. Choose glass only if absolute clarity, a classic look, and multi-decade lifespan matter more than cost, weight, and safety. For the widest range of home growers, twin-wall polycarbonate is the smarter greenhouse.