A Riga greenhouse is a German-made polycarbonate greenhouse built for snow, wind and real winter growing. Its onion-shaped roof sheds snow, and its thick twin-wall or triple-wall panels hold heat. If you want to grow through a cold winter, it is one of the strongest kits we sell.
✅ Quick answer
- Made by Hoklartherm in Germany and sold in the US through Exaco.
- Riga S and standard Riga models use 8mm twin-wall sides and 10mm ends. The Riga XL uses 16mm triple-wall panels.
- The Riga 4 and 5 are engineer-certified for 120 mph gusts and a 30 psf ground snow load.
- Sizes run from 54 to 413 sq ft of floor space.
- Warranty: 15 years on the frame, 10 years on the polycarbonate.
- A Riga cannot be extended later, so the maker suggests buying one size bigger than you planned.
We are a small, woman-owned greenhouse business in Georgia, and we answer every question personally. Customers in snowy states often ask us about the Riga. This review covers what we tell them: the sizes, the ratings, the trade-offs and who it suits best.
What is a Riga greenhouse?
The Riga is a freestanding greenhouse from Hoklartherm, a German greenhouse maker. In the US it is distributed by Exaco. It uses a strong aluminum frame and polycarbonate glazing, not glass.
Hoklartherm describes the Riga as a true greenhouse for growing vegetables, herbs and flowers in midwinter. The maker calls kits with less than 8mm twin-wall glazing "season extenders". Those suit light frost in spring and fall, but cost too much to heat all winter.
- Frame: high-strength aluminum profiles that are permanently joined, so they don't work loose in the wind.
- Glazing: German-made polycarbonate, held with rubber seals.
- Door: a wide Dutch barn door with a keyed lock. You can open just the top half for air.
- Vents: roof windows with automatic openers, plus an oversized rear window.
Is a Riga greenhouse good for snow and wind?
Yes. This is what the Riga is known for. Three things make it a strong greenhouse for snow.
- The roof shape. The curved, pointed "onion" roof helps snow slide off instead of piling up.
- The frame. Profiles are permanently joined, and the glazing panels have no crossbars. Hoklartherm rates the roof load at up to 150 kg/m², about 31 psf.
- The certification. A licensed structural engineer reviewed the Riga 4 and Riga 5 in 2016. The letter rates them for 120 mph 3-second gusts and a 30 psf ground snow load. It uses the 2012 International Building Code.
⚠️ Read the fine print: the engineer's rating assumes a build per the manual. It also needs a continuous foundation profile buried full-height around the perimeter. That is why the foundation frame matters. The letter covers the Riga 4 and 5. Ask us for the documents for other sizes.
How does 30 psf compare to your area? Your local building department can tell you the design ground snow load for your address. In heavy-snow areas, brush off deep, wet snow after big storms, whatever greenhouse you own.
For the toughest kits we carry side by side, see the most durable greenhouses for wind, snow and harsh winters.
What Riga greenhouse sizes are there?
There are three widths. The Riga S models are about 7 ft 8 in wide. Standard Riga models are 9 ft 8 in wide, and the Riga XL is 14 ft wide. Each comes in several lengths.
| Model | Size (W × L) | Floor space | Glazing (sides / ends) | Starting price* |
|---|---|---|---|---|
| Riga 2s | 7'8" × 7' | 54 sq ft | 8mm / 10mm twin-wall | about $4,399 |
| Riga 3s | 7'8" × 10'6" | 81 sq ft | 8mm / 10mm twin-wall | about $4,699 |
| Riga 4s | 7'8" × 14' | 108 sq ft | 8mm / 10mm twin-wall | about $5,199 |
| Riga 3 | 9'8" × 10'6" | 102 sq ft | 8mm / 10mm twin-wall | about $4,999 |
| Riga 4 | 9'8" × 14' | 135 sq ft | 8mm / 10mm twin-wall | about $8,099 |
| Riga 5 | 9'8" × 17'6" | 165 sq ft | 8mm / 10mm twin-wall | about $9,199 |
| Riga XL 5 | 14' × 16'5" | 231 sq ft | 16mm triple-wall | about $16,172 |
| Riga XL 6 | 14' × 19'10" | 280 sq ft | 16mm triple-wall | about $18,499 |
| Riga XL 7 | 14' × 23' | 322 sq ft | 16mm triple-wall | about $19,454 |
| Riga XL 8 | 14' × 26'3" | 368 sq ft | 16mm triple-wall | about $21,999 |
| Riga XL 9 | 14' × 29'6" | 413 sq ft | 16mm triple-wall | about $22,999 |
*Prices checked in November 2026. Prices can change and sales may apply, so click the model name to see today's price. Starting prices are for the base option; colors, kits and add-ons change the price.
See every size, with photos and today's prices, in our Riga greenhouse collection.
💡 Sizing tip: choose one size bigger than you think you need. You can't add length later, and benches fill up fast.
Riga vs Riga XL: what is the difference?
The XL is not just a longer Riga. It is wider, taller and better insulated.
| Feature | Riga S and Riga | Riga XL |
|---|---|---|
| Width | About 7'8" or 9'8" | 14' |
| Glazing | 8mm twin-wall, 10mm in end walls | 16mm triple-wall |
| Doors | One Dutch barn door | Two Dutch barn doors, 37.5" × 74" |
| Roof windows | Up to 4 (40" × 24") | 4 to 8 (XL 6 to 9: 40" × 39.5") |
| Assembly | 2 people, 1 full day (6-8 hours with 3) | 2-3 people, 2 full days |
Thicker glazing holds heat better. If you plan to heat all winter, the XL costs less to heat per square foot of growing space.
How much does it cost to heat a Riga greenhouse?
Heating depends on surface area, glazing and the temperature gap. You can estimate it with one formula.
📐 The greenhouse heat formula
BTU per hour = Surface area × U-value × Temperature gap
Surface area = walls + roof in sq ft · U-value about 0.7 for twin-wall and 0.6 for triple-wall polycarbonate · Gap = inside °F minus coldest outside °F
🧮 Worked example: a Riga XL 6 on a 10°F night
- Surface area (walls + roof): about 744 sq ft, our estimate from its dimensions
- U-value for 16mm triple-wall polycarbonate: 0.6
- Keep it 45°F inside when it is 10°F outside: a gap of 35°F
744 × 0.6 × 35 = about 15,600 BTU per hour. Divide by 3.412 = about 4,600 watts. Add 20% for safety = about 5,500 watts. That is a job for a 240V heater on its own circuit.
The U-values are planning numbers from Greenhouse Management magazine. For monthly costs by size, read how much it costs to heat a greenhouse in winter. You will find heaters in our greenhouse heater collection.
How do you install a Riga greenhouse?
Riga kits come with written instructions and an assembly video. The maker lists one full day for two people on the S and standard models. The XL takes two to three people about two days.
We highly recommend the Riga foundation frame. It bolts to the greenhouse bottom and sits in a 6-inch trench. You don't need a concrete slab. It was about $824 when we wrote this (November 2026). Some sizes offer an accessory kit that bundles the frame with shelves.
- Delivery: free curbside LTL freight to the continental US. Someone must be home to receive it.
- Stem wall: building on a low wall? Door extension kits are available for most sizes.
- Prefer not to build it? We can point you to assembly crews our customers have used.
Our full greenhouse installation guide walks through the base, square check and anchoring step by step.
What are the pros and cons of a Riga greenhouse?
What we like
- Proven snow and wind strength, backed by an engineer's letter for the Riga 4 and 5
- Thick glazing that makes year-round growing affordable to heat
- Automatic roof vents and a split barn door for easy airflow
- Long frame warranty of 15 years
- Wide range of sizes, from a 54 sq ft starter to a 413 sq ft XL
What to consider
- Polycarbonate diffuses light, so you don't get the crystal-clear view of glass
- A Riga can't be lengthened later, so size up from the start
- It costs more than thin-wall hobby kits
- The XL is a two-day build and needs a big, level site
How does the Riga compare to other winter greenhouses?
The Riga is not the only good choice for cold weather. Here is how we help customers decide.
- Choose a Riga if snow and wind are your main worries, and you want strong insulation without glass.
- Choose an insulated glass greenhouse like the Livingten if you want a clear view and a garden-room feel. Read our Livingten review.
- Choose a Riverstone MONT if you want a large polycarbonate kit with a different style. See how the MONT handles winter.
Is a Riga greenhouse worth it?
For gardeners in snowy or windy places who want to grow all winter, we think it is. You pay more up front than for a light hobby kit. In return you get a frame built to stay put and glazing that keeps heating bills down.
If you only need frost protection in spring and fall, a lighter kit may be enough. Tell us your zone and goals, and we will give you an honest answer. We offer free shipping to the continental US, and we answer every call and email ourselves.
📌 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 (November 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.
Frequently asked questions
Who makes the Riga greenhouse?
Hoklartherm, a greenhouse maker in Germany, designs and builds the Riga. Exaco distributes it in the United States.
How much snow can a Riga greenhouse hold?
An engineer certified the Riga 4 and 5 for a 30 psf ground snow load. That assumes a build per the manual, with the full perimeter foundation. Hoklartherm rates the roof load at up to 150 kg/m². Clear deep, wet snow after big storms.
Can you grow in a Riga greenhouse all winter?
Yes, with a heater sized for your climate. Hoklartherm designed it for winter growing, using 8mm or thicker twin-wall glazing. The XL's 16mm triple-wall panels hold heat best.
Do I need a foundation for a Riga greenhouse?
Yes. We highly recommend the Riga foundation frame, set in a 6-inch-deep trench. The engineer's rating for the Riga 4 and 5 assumes that full perimeter foundation.
How long does it take to build a Riga greenhouse?
The S and standard models take two people one full day, or 6 to 8 hours with three people. The Riga XL takes two to three people about two days.
Can I make my Riga longer later?
No. Riga greenhouses cannot be extended after you buy them. That is why the maker suggests choosing one size bigger than you planned.
Thinking about a Riga greenhouse?
Tell us where you live and what you want to grow. We will help you pick the right Riga size, foundation and heater, and let you know about current sales.
