The best hobby polycarbonate greenhouse has 8mm or thicker twin-wall panels and a strong aluminum frame. It should also have a real snow and wind rating. Our top picks: the Riverstone MONT for value, the Riga for year-round growing and the Riga XL for big growers. Below, we compare all eight side by side.
✅ Quick answer
- Best value: Riverstone MONT 8x12. Made in the USA, 8mm twin-wall, rated for 24 lbs/sq ft of snow and 65 mph wind.
- Best all-rounder: Hoklartherm Riga 4. German-made, 8mm twin-wall walls and roof, 135 sq ft of floor space.
- Best for serious winter growing: Riga XL 6. 16mm triple-wall polycarbonate and 280 sq ft.
- Best small modern design: KGT Hoklartherm Linea II (10mm) or Santini II (16mm).
- Panels thinner than 8mm work best as season extenders, not true winter greenhouses.
We are a small, woman-owned greenhouse business in Georgia. We answer every question ourselves, and “which polycarbonate greenhouse should I buy?” is one we hear every week. This guide shares the same advice we give on the phone.
What makes a good hobby polycarbonate greenhouse?
A hobby greenhouse is a backyard house for growing at home. Polycarbonate is a tough, light plastic that is very hard to break. It is the most popular glazing for hobby kits. Five things separate a great one from a flimsy one:
- Panel type and thickness. Twin-wall and triple-wall panels trap air between layers, like a double-pane window. Thicker panels hold more heat.
- Frame strength. Heavy aluminum profiles resist snow, wind and rust. Thin frames bend.
- Snow and wind ratings. Good makers publish them in pounds per square foot (psf) and miles per hour (mph).
- Ventilation. Roof vents, ideally with automatic openers, stop summer overheating.
- Warranty. Look for separate coverage on the frame and the panels.
Is twin-wall polycarbonate better than single-wall?
Yes, for anything beyond spring and fall. Single-wall panels let in lots of light but hold very little heat. Twin-wall panels diffuse the light, which helps prevent leaf scorch. They also lose nearly half as much heat as single glass.
Hoklartherm, the German maker of the Riga, puts it plainly. Greenhouses with less than 8mm twin-wall are “season extenders.” They protect plants from a light frost. But they cost too much to heat through a real winter.
📌 Light and lifespan: clear twin-wall polycarbonate lets through roughly 80% of sunlight, a little less than clear glass. In return, you get far better insulation and almost no breakage. Oklahoma State University Extension lists an expected life of about 10 to 15 years for polycarbonate. That is why panel warranties matter.
How do the top 8 hobby polycarbonate greenhouses compare?
Here are our eight picks, all sold by us with free shipping to the continental US. Specs come from each model's product page.
| Model | Glazing | Floor space | Snow / wind rating | Approx. price* |
|---|---|---|---|---|
| Riverstone MONT 8x12 | 8mm twin-wall | 8 x 12 ft | 24 psf / 65 mph | about $4,150 |
| Hoklartherm Riga 2s | 8mm twin-wall, 10mm ends | 8 x 7 ft | Certified; see listing | about $6,000 |
| Hoklartherm Riga 4 | 8mm twin-wall, 10mm ends | 135 sq ft | Certified; see listing | about $8,100 (silver) |
| Hoklartherm Riga XL 6 | 16mm triple-wall | 280 sq ft | Certified; see listing | about $17,340 |
| Cross Country Sunhaven 8x8 | 6mm twinwall | 64 sq ft | 32 psf / 85 mph | about $8,600 |
| KGT Hoklartherm Linea II | 10mm twin-wall | 65 sq ft | 25 psf snow | about $5,950 |
| KGT Hoklartherm Santini II | 16mm triple-wall | 67 sq ft | 25 psf snow | about $8,500 |
| Janssens Royal Victorian VI34 | Polycarbonate roof, glass walls | 150 sq ft | Not listed | about $15,000 (hybrid) |
*Prices checked in October 2026. Prices can change and sales may apply, so click the model name to see today's price.
Which hobby greenhouse is the best value?
1. Riverstone MONT 8x12: best value, made in the USA
The MONT is built in the USA from heavy extruded aluminum with a black painted finish. It uses 8mm twin-wall polycarbonate on the walls and roof. That is the same thickness Hoklartherm calls the minimum for winter growing.
- 7 ft 6 in peak height, so tall gardeners can stand up
- Hinged double doors, almost 6 ft high and 4½ ft wide
- Two 2x2 ft roof vents with automatic openers and built-in rain gutters
- Rated for 24 lbs/sq ft of snow and 65 mph wind
- 10-year warranty on the frame and polycarbonate
You can add a 4 ft extension later, which the Riga can't do. A Growers Edition adds a work bench, shade cloth and a watering system. See every size in our Riverstone MONT collection.
💡 Had your eye on a Solexx? Solexx greenhouses are no longer made. If you liked their insulated, diffused-light panels, the MONT and the Riga are the closest replacements we carry. Both use 8mm twin-wall polycarbonate on a heavy aluminum frame.
Which polycarbonate greenhouse is best for winter?
2 and 3. Hoklartherm Riga 2s and Riga 4: the year-round favorites
The Riga is made in Germany by Hoklartherm. Its rounded “onion” shape sheds snow and handles strong wind. The frame profiles are permanently joined, so they won't work loose over time.
The Riga 4 gives you 135 sq ft and 7 ft 6 in of walking height in the middle. It has 8mm twin-wall on the main body and 10mm on the end walls. Two roof windows and an oversized rear window open automatically as the temperature changes.
- Warranty: 15 years on the frame, 10 years on the polycarbonate
- Assembly: about one full day with two people
- Tip: Rigas can't be extended, so the maker suggests buying one size bigger than you planned
Short on space? The Riga 2s has the same build in an 8x7 footprint. See all sizes in our Riga greenhouse collection.
4. Hoklartherm Riga XL 6: the most room for winter growing
The Riga XL 6 steps up to 16mm triple-wall polycarbonate. It measures 14 ft wide by 19 ft 10 in long, with 280 sq ft inside. Two Dutch barn doors, a tall rear window and four automatic roof windows keep air moving.
It carries the same 15-year frame and 10-year panel warranty as the Riga 4. Plan on two full days to build it with two or three people, or ask about our assembly crews.
Which small polycarbonate greenhouse is best?
5. Cross Country Sunhaven 8x8: the toughest ratings
The Sunhaven 8x8 has our highest published ratings: 32 lbs/sq ft of snow and 85 mph wind. Its aluminum frame members sit every 2 feet. It uses 6mm twinwall polycarbonate with 82% light diffusion and an R-value of 1.62.
It has 64 sq ft of floor space, 5 ft 6 in side walls and a 7 ft 8 in peak. You can pick a white, brown or green frame. Prefer glass? Cross Country also makes the Parkside glass greenhouse.
6 and 7. KGT Hoklartherm Linea II and Santini II: modern and compact
These two share a sleek, single-slope design with an anthracite grey frame. Both measure 9 ft 9 in wide by 6 ft 8 in deep and are made in Germany. Each has a lockable split Dutch door, a large rear window and two vent windows.
- Linea II: 10mm twin-wall, 65 sq ft, 25 lbs/sq ft snow rating. A glass-wall version is also available.
- Santini II: 16mm triple-wall, 67 sq ft, 25 lbs/sq ft snow rating. Our best-insulated small greenhouse.
Both double as a lockable garden room for tools or bikes. They suit patios and small modern yards where looks matter.
Can you get a Victorian greenhouse with a polycarbonate roof?
8. Janssens Royal Victorian VI34: elegance with a poly roof
Want classic Victorian style? The Royal Victorian VI34 comes in all glass or as a hybrid. The hybrid has a polycarbonate roof and glass side walls. The poly roof adds insulation and diffused light overhead. The glass walls keep the clear, elegant look.
It gives you 150 sq ft, 6 ft 7 in side walls and a 9 ft peak. A foundation frame, automatic roof window openers and a misting system are included. It is made by Janssens in Belgium. For the bigger 13x20 model, read our Royal Victorian VI46 review.
How much does a hobby polycarbonate greenhouse cost per square foot?
Sticker price alone can fool you. A bigger greenhouse often costs less for each square foot of growing space. Here is the quick math we use with our customers.
📐 Cost per square foot
Cost per sq ft = Kit price ÷ Floor space (sq ft)
Use the price on today's product page · Floor space is on the spec list
🧮 Worked example: Riga 4 vs. Riga XL 6
- Riga 4: about $8,100 ÷ 135 sq ft = about $60 per sq ft
- Riga XL 6: about $17,340 ÷ 280 sq ft = about $62 per sq ft
The XL 6 costs twice as much, yet each square foot costs about the same. And you get thicker 16mm triple-wall panels. These are estimates from October 2026 prices.
| Model | Approx. price* | Floor space | Est. cost per sq ft |
|---|---|---|---|
| Riverstone MONT 8x12 | about $4,150 | about 96 sq ft | about $43 |
| Hoklartherm Riga 4 | about $8,100 | 135 sq ft | about $60 |
| Hoklartherm Riga XL 6 | about $17,340 | 280 sq ft | about $62 |
| KGT Linea II | about $5,950 | 65 sq ft | about $92 |
| Royal Victorian VI34 hybrid | about $15,000 | 150 sq ft | about $100 |
| Cross Country Sunhaven 8x8 | about $8,600 | 64 sq ft | about $134 |
*Prices checked in October 2026. Prices can change and sales may apply, so click the model name to see today's price. MONT floor space is based on its 8x12 nominal size.
📌 About prices: manufacturers update their prices during the year, and we often run sales and promotions. The price on the product page is always the current one. Prices in this article are a guide from when we wrote it (October 2026), not a quote or guarantee. Found a lower price for the same model at an authorized retailer? We offer a Price Match Guarantee - please check the rules first. Call us and we will confirm today's price and any current deals.
How do I choose the right polycarbonate greenhouse kit?
Work through these steps, in this order:
- Decide your season. Spring and fall only? Thinner panels are fine. Growing all winter? Choose 8mm twin-wall or thicker.
- Check your weather. Match the snow and wind rating to your area. In heavy snow country, look at the Riga, Riga XL or Sunhaven.
- Size up. Most of our customers wish they had bought bigger. Add one size if you can.
- Plan the base. Every kit needs a level, anchored foundation. Our practical guide to a greenhouse foundation explains your options.
- Budget for heat and air. A heater, fan and thermostat are part of the real cost of winter growing.
💡 Winter tip: thicker panels mean a smaller heating bill every month. To see real numbers for the Riga and Riga XL, read how much it costs to heat a greenhouse in winter. For storm country, see our most durable greenhouses for wind and snow.
Every greenhouse here ships free to the continental US. Our assembly crews can build it for you, too. Not sure which one fits your yard? Call us, and we will talk it through with you personally.
Frequently asked questions
What is the best hobby polycarbonate greenhouse?
For most home gardeners, the Hoklartherm Riga 4 is our top pick. It has 8mm twin-wall panels, 135 sq ft and a 15-year frame warranty. On a tighter budget, the USA-made Riverstone MONT 8x12 is the best value.
What thickness of polycarbonate do I need for winter?
Choose at least 8mm twin-wall for year-round growing. In very cold areas, 16mm triple-wall, like the Riga XL or Santini II, holds even more heat. Thinner panels are best for spring and fall.
How long does a polycarbonate greenhouse last?
A good aluminum frame can last for decades. UV-coated polycarbonate panels usually last about 10 to 15 years before they yellow. Check the panel warranty: the Riga and MONT both cover the polycarbonate for 10 years.
Is polycarbonate better than glass for a greenhouse?
Polycarbonate insulates better, diffuses light and is very hard to break. Glass lets in a little more light and lasts longer. But single glass costs more to heat. Many gardeners choose polycarbonate for winter growing.
Does a polycarbonate greenhouse need a foundation?
Yes. Every kit needs a level, solid base and proper anchoring. The base keeps the frame square and holds it down in wind. Some kits, like the Royal Victorian, include a foundation frame.
Do you still sell Solexx greenhouses?
No. Solexx greenhouses are no longer made. We suggest the Riverstone MONT or the Hoklartherm Riga instead. Both use 8mm twin-wall polycarbonate.
Need help choosing?
Tell us your yard size, your climate and what you want to grow. We will help you pick the right polycarbonate greenhouse and let you know about any current sales.