Glass gives you a crystal-clear view and the most direct light. Twin-wall polycarbonate holds heat better, softens harsh sun and shrugs off hail. For most cold or stormy climates, polycarbonate (or a glass greenhouse with a polycarbonate roof) is the practical pick. For a garden showpiece in a milder climate, tempered glass is hard to beat.
โ Quick answer
- Choose glass if you want a clear view, a classic look and full sun for fruiting crops, and you can add shading in summer.
- Choose polycarbonate if you want lower heating bills, soft even light and the best protection from hail and falling branches.
- Choose a hybrid (glass walls, polycarbonate roof) if you want the view of glass with a hail-safe, warmer roof.
- For real winter growing, look for 8mm twin-wall polycarbonate or thicker, or insulated glass.
- Single-pane glass loses about twice the heat of twin-wall polycarbonate.
We are a small, woman-owned greenhouse business in Georgia, and "glass or polycarbonate?" is one of the first questions our customers ask. This guide brings together everything we tell them, so you can choose with confidence before you buy.
What is the difference between glass and polycarbonate glazing?
"Glazing" is the clear part of a greenhouse: the walls and roof panels. There are four main types.
- Tempered glass. Safety glass that is heat-treated to be much stronger than window glass. If it breaks, it falls into small pieces instead of sharp shards. Most kits use 3mm. Janssens uses 4mm.
- Twin-wall (or multiwall) polycarbonate. A tough plastic sheet with two or more layers and air channels between them. The trapped air is what insulates. Common thicknesses are 6mm, 8mm, 10mm and 16mm.
- Insulated glass. Two panes of glass with a sealed gas gap, like a home window. The Livingten uses 22mm dual-pane glass.
- Hybrid. Glass walls with a polycarbonate roof. You keep the view at eye level and get a stronger, warmer roof.
Glass vs polycarbonate: side-by-side comparison
| Feature | Tempered glass | Twin-wall polycarbonate | Hybrid |
|---|---|---|---|
| View | Crystal clear | Frosted, soft light | Clear walls |
| Light | Most direct light | Diffused, fewer hot spots | Direct from the sides, diffused from above |
| Holds heat | Low | Good to very good | In between |
| Hail and impact | Can crack in large hail | Best; nearly unbreakable | Very good |
| Weight | Heavy; needs a solid base | Light; must be anchored well | Heavy |
| Looks over time | Never yellows or clouds | UV-coated panels last many years | Both |
| Our examples | Janssens, Alton, Livingten | Riga, Riga XL, MONT | Cross Country Legacy, Royal Victorian hybrid |
Which lets in more light, glass or polycarbonate?
Glass lets in the most direct light. Light-hungry crops like tomatoes, cucumbers, peppers and citrus love it, and it gives you a clear view of your garden from inside.
Polycarbonate scatters the light as it passes through. The light is a little softer, but it reaches every corner and the underside of leaves, and it creates fewer hot spots. Leafy greens, herbs, seedlings, orchids and other delicate plants often do better under it.
Which holds heat better in winter?
Polycarbonate, by a wide margin, unless you choose insulated glass. Each glazing has a "U-value" that shows how fast heat escapes. Lower is better.
| Glazing | U-value | Heat loss vs. single glass |
|---|---|---|
| Single-pane glass | 1.25 | 100% |
| Twin-wall polycarbonate | 0.7 | About 56% |
| Triple-wall polycarbonate | 0.6 | About 48% |
| Insulated glass | 0.7 or better | About 56% or less |
Planning U-values from Greenhouse Management magazine and University of Arkansas extension data.
Hoklartherm, the maker of the Riga, puts it simply: greenhouses with less than 8mm twin-wall are "season extenders." They cost too much to heat through a true winter. If you want to grow all winter, start at 8mm. Our guide to the cost to heat a greenhouse in winter shows the monthly difference with real numbers.
Which is stronger in hail, wind and snow?
Hail: polycarbonate wins. It flexes on impact instead of cracking. On many glass greenhouses, glass broken by large hail or falling objects is not covered by the warranty, so if large hail is common where you live, choose a polycarbonate roof.
Wind and snow: the frame, roof shape and anchoring matter more than the glazing. A strong aluminum frame with either material can be very tough. Compare each model's published snow (psf) and wind (mph) ratings. Our guides to the most durable greenhouses for wind, snow and harsh winters and greenhouses with the best weather-impact resistance list the ratings for each model we carry.
๐ Good to know: glass is heavier, so it needs a solid concrete or block foundation. Polycarbonate is light, so it must be bolted down well. Our practical guide to a greenhouse foundation covers both.
Which is better in summer?
Both work well in summer if you manage heat and light. They just need different help.
- Glass lets full sun through, so leaves can scorch on hot afternoons. Plan on shade cloth, roof vents and an exhaust fan in hot southern summers.
- Polycarbonate diffuses the light and blocks most UV, so plants are less stressed. It still traps heat, so it needs good ventilation too, but usually less shading.
In much of the South, glass greenhouses do very well with good shading. In hot, sunny climates with strong hail, polycarbonate or a hybrid is the easier choice.
What is a hybrid greenhouse, and is it worth it?
A hybrid has glass walls and a polycarbonate roof. The roof is where hail hits, snow sits and most heat escapes, so putting polycarbonate up there fixes glass's biggest weak spots. You still get a clear view at eye level.
- The Cross Country Legacy 8x8 pairs 3mm tempered glass walls with a 6mm twin-wall roof. It is rated for 32 psf of snow and 85 mph of wind.
- The Janssens Royal Victorian VI46 comes all-glass or as a hybrid with 4mm tempered glass walls and a polycarbonate roof.
For snowy or hail-prone areas where you still want the look of glass, a hybrid is often the best of both.
Which is best for my climate?
| Where you live | Our usual advice |
|---|---|
| Cold, snowy north | 8mm+ polycarbonate (Riga, Riga XL), a hybrid, or insulated glass (Livingten) |
| Hail belt and plains | Polycarbonate roof at least, plus a published wind rating |
| Mild or moderate | Any glazing works; choose by look and what you grow |
| Hot, sunny South | Glass with shading and good vents, or polycarbonate for softer light |
Which is better for what I want to grow, or use it for?
- Tomatoes, peppers, cucumbers, citrus: glass, or polycarbonate in cold areas where heat matters more than light.
- Greens, herbs, seedlings, winter crops: polycarbonate. Diffused light and steady temperatures suit them.
- A garden room, studio or yoga space: glass. The clear view is the point. See our orangeries and Victorian greenhouses.
- Schools and busy yards: polycarbonate, or tempered glass, which breaks into small pieces. Keep mowers and string trimmers well away from glass panels.
How long does each last, and how much care does it need?
- Glass never yellows or clouds. Wash it a few times a year with mild soap and water. Check seals and replace a cracked pane promptly.
- Polycarbonate has a UV-protective layer. Clean it with a soft cloth or sponge and mild soap only. Never use abrasive pads or harsh solvents, which damage the coating. The Riga carries a 10-year warranty on its polycarbonate, per our listing.
Either way, the frame does most of the work over the years. Thick aluminum profiles and good seals are what keep a greenhouse tight for decades.
Does glass or polycarbonate cost more?
Size, frame and brand move the price far more than the glazing does. Here is where a few popular models started when we wrote this.
| Model | Glazing | Approx. starting price (Oct 2026) |
|---|---|---|
| Riverstone MONT 8x12 | 8mm twin-wall poly | About $4,150 |
| Hoklartherm Riga 4 | 8mm twin-wall poly | About $8,100 |
| Cross Country Legacy 8x8 | Hybrid | About $9,500 |
| Janssens Royal Victorian VI46 | 4mm tempered glass | About $16,600 |
| Hoklartherm Livingten | 22mm insulated glass | About $47,000 |
๐ About prices: manufacturers update prices during the year, and we often run sales. The price on the product page is always the current one. Prices here are a guide from October 2026, not a quote. Found a lower price for the same model at an authorized retailer? See our Price Match Guarantee.
Also think about running costs. In a cold climate, the money you save on heat with good glazing can add up to hundreds of dollars a year. Every greenhouse we sell ships free to the continental US.
Frequently asked questions
Is glass or polycarbonate better for a greenhouse?
Neither is better everywhere. Glass gives the clearest view and most direct light. Twin-wall polycarbonate holds heat better and resists hail. Pick by your climate, what you grow and the look you want.
Do plants grow better under glass or polycarbonate?
Sun-loving fruiting crops often do best under glass. Greens, herbs and seedlings often do better under polycarbonate's diffused light. Both grow healthy plants with good ventilation and the right temperature.
Is polycarbonate warmer than glass?
Yes. Twin-wall polycarbonate loses roughly half the heat of single-pane glass. Insulated glass, like the Livingten's 22mm panes, closes that gap.
Does polycarbonate turn yellow?
Quality greenhouse polycarbonate has a UV-protective layer that slows yellowing for many years. Cleaning it gently, without abrasives, helps it last.
Is a glass greenhouse safe around kids and pets?
Greenhouse glass should be tempered safety glass, which is far stronger than window glass and breaks into small pieces. For very busy yards or schools, polycarbonate is the most forgiving.
Can I use a glass greenhouse in winter?
Yes, with a heater and a solid foundation. It costs more to heat than polycarbonate. In snowy areas, choose a strong frame, a hybrid roof or insulated glass.
Still deciding?
Tell us where you live and what you want to grow. We will help you choose the right glazing and greenhouse, and let you know about any current sales. You can also browse our glass greenhouses and polycarbonate greenhouses.