Riga Black Greenhouse
Price range: $10,999.00 through $12,999.00
Features
- Garden-room styling: black powder-coated frame with Victorian cast metal roof cresting
- Crystal-clear front: 6mm clear polycarbonate on the front gable for real visibility
- Insulated where it counts: 8mm twin-wall sidewalls + 10mm twin-wall rear gable, paired with tight rubber seals for steadier temps
- Built to shed weather: curved sidewalls help snow slide off and wind flow over instead of pushing against flat panels
- Rigid 13-gauge aluminum frame, made in Germany with tight-fit construction for a solid, long-term structure
- Break-resistant, UV-protected polycarbonate that resists yellowing and brittleness over time
- Smart cross-breeze setup: Dutch door + rear wall window lets you vent heat effortlessly while keeping critters out
- Automatic roof vent openers included for hands-free passive venting as temps rise
What's Included
- Frame + glazing + hardware
- Victorian cast metal roof cresting
- Roof vents with automatic openers (qty varies by size)
- Lockable Dutch door (+ keys)
- Rear window with manual opener
Dimensions
Available in 2 sizes:
- Riga 4: 9′ 8″ W x 14′ L x 7′ 7″ H
- Riga 5: 9′ 8″ W x 17′ 6″ L x 7′ 7″ H
Shipping
- Ships via LTL freight (curbside): Liftgate + pallet jack delivery; plan 2–3 people to move boxes off the pallet and into place.
- Lead time: 5–7 business days (in stock). Up to 12 weeks (if not in stock).
Assembly & Warranty
- Average assembly time: approx. 2-3 days with 2-3 people (it’s better to have 4 people for final assembly day)
- Assembly Manual: Download here
- Assembly of a Riga 3: Watch our assembly video here!
- Warranty: 10 years on polycarbonate (prorated after 5 years), 15 years on frame
Secure Checkout
Nationwide Delivery
Veteran-Owned
Real Greenhouse Owners
Personalized Planning Help
Description
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The Riga Black takes the greenhouse we recommend most for rough weather and gives it the look of a true garden room. Same German-built gothic-arch structure, same insulated twin-wall panels — now with a black powder-coated frame, Victorian roof cresting, and a clear front wall.
That clear front changes how the space feels. Instead of working behind frosted panels, you look out at your garden — and from the outside, the Riga Black looks like a destination, not equipment. If you’ve wanted the Riga’s strength but hesitated on its workhorse look, this is the version to get.
A Riga You’ll Want to Look At
Most tough greenhouses look tough — and that’s it. The Riga Black pairs the same rugged structure with a black powder-coated aluminum frame and Victorian cast metal roof cresting, included in the kit rather than sold as an upgrade.
The result sits comfortably next to modern homes, dark trim, and designed outdoor spaces. It’s a greenhouse that adds to your yard’s look instead of hiding behind it.
A Clear View In (and Out)
The standard Riga uses translucent twin-wall panels all around — great for insulation, but you can’t really see through them. The Riga Black swaps the front gable and door for 6mm crystal-clear polycarbonate, so you get an actual view: out toward your garden while you work, and into a bright, plant-filled space from your patio.
If you’re picturing your greenhouse as a place to be — morning coffee, potting sessions, a quiet hour with the door open — this is the difference you’ll notice every day.
Worth knowing: single-layer clear panels insulate less than twin-wall. The curved side walls and rear gable — the bulk of the surface area — stay fully insulated, so for most climates the trade-off is small. If you grow through hard winters, plan your heater the same way you would for any greenhouse.
Built the German Way
Under the styling, this is still a Riga: a rigid 13-gauge aluminum frame with precise, tight-fit construction and rubber seals that keep every panel snug — no rattling, no shifting over time.
The curved sidewall profile does quiet work too: snow slides off instead of piling up, and wind flows over the shape instead of pushing against flat walls. It’s the “solid feel” difference that budget greenhouses often don’t have.
Polycarbonate That Stays Clear
All panels — twin-wall and clear alike — are highly break-resistant and UV-protected, made to resist the yellowing, brittleness, and cloudiness that cheap polycarbonate develops after a few summers.
The 8mm twin-wall side walls and 10mm twin-wall rear gable hold warmth in during cold-season growing, so the clear front stays a design choice — not a compromise on how the greenhouse performs.
Fast Venting When You Need It
The Riga Black is built for effortless airflow: swing open the top half of the Dutch door, crack the rear wall window, and you’ve got a full-length cross-breeze pulling air through the greenhouse — while the closed bottom door keeps rabbits, chickens, and curious pets out.
And on days you’re not around, the roof takes over. The automatic wax-cylinder vent openers react to temperature on their own — no electricity, no timers — opening as the greenhouse warms and easing shut as it cools.
Add-Ons & Upgrades: Make it your own
Shelving
Add a full-length shelf, narrow top shelf, or slatted shelving to keep tools and plants organized—and create an easy workspace without eating up floor space.
Drop Door Kit (for stem wall installs)
Made for raised installs so your entry stays clean and comfortable—ideal when you’re building up on a stem wall (up to ~20″). Add the Drop Door Kit here!
Foundation Frame
If you want an easy way to anchor the Riga Greenhouse without a concrete or wood foundation, add the foundation frame. All you need is digging a trench that this frame sits in.
Quick Size Guide
Peak height: 7’7″
Sidewall: 5’1″ interior height (measured 1′ in from wall)
Roof pitch: 30°
| Size | Actual Dimensions | Floorspace |
|---|---|---|
| Riga 4 | 9′ 8″ W x 14′ L | 140 sq ft |
| Riga 5 | 9′ 8″ W x 17′ 6″ L | 180 sq ft |
Every Riga Greenhouse kit includes:
- Aluminum framing
- Glazing:
- 6mm clear polycarbonate for the front gable
- 8mm twin-wall polycarbonate for the roof/sidewalls
- 10mm twin-wall polycarbonate for the end gable
- Lockable Dutch door (30″ x 72″)
- Rear wall window (30″ x 42″)
- Roof vents (40″ x 24″) with auto openers (qty below)
- Wedge seals
- Hardware
| Vent Type | Riga 3 | Riga 4 | Riga 5 |
|---|---|---|---|
| Roof Vent | 1 | 2 | 4 |
Specifications
| Brand | Hoklartherm/KGT |
|---|---|
| Distributed by | Exaco |
| Made in | Germany |
| Width | 10' |
| Length | 14', 18' |
| Floorspace | 140 sq ft, 180 sq ft |
| Peak Height | 7′ 7″ |
| Side Wall Height | 5'1" |
| Framing Material | Aluminum |
| Frame Color | Black |
| Roof Glazing | 8mm twin-wall polycarbonate |
| Wall Glazing | 10mm twin-wall polycarbonate, 6mm single-wall polycarbonate |
| Roof Pitch | 30° |
| Roof Vent Opener Type | Automatic (wax) |
| Roof Vent Dimensions | 40" x 24" |
| Door Type | Dutch |
| Door Dimensions | 30″ x 72″ |
| Foundation Frame | Available Separately |
| R-Value | 2.0 |
| Rainwater Collection | No |
| Stem Wall Compatibility | Yes |
| Expandable | No |
| Warranty | 10 years (prorated after 5 years) on polycarbonate, 15 years on frame |
How is the Riga Black different from the standard Riga?
Three things: a black powder-coated frame, a crystal-clear 6mm polycarbonate front (gable and door) instead of translucent twin-wall panels, and Victorian cast metal roof cresting included in the kit. The frame, curved profile, and ventilation setup are shared with the standard Riga line.
What foundation do I need?
Your foundation needs to be level, square, and well-draining—that matters more than the material. A treated wood beam base (anchored) or the optional foundation frame works well for many installs. For maximum stability, go with concrete blocks/pavers or a poured concrete perimeter/slab.
Helpful guides:
Is This a Heavy-Snow Greenhouse?
Yes—Riga is designed for winter weather. The gothic-arch roof helps snow shed off the sides more naturally, which means less buildup and less maintenance during snow season. For areas with very heavy snowfall or stricter local requirements, you can also add reinforcement options (like cross braces/center supports) to increase structural strength and peace of mind.
Do the roof vent openers require electricity?
No. They are wax-cylinder openers, which expand and contract with temperature to open/close the vent—so there’s no wiring and no power required.
Are There any accessories I should add?
If it fits your layout, full-length shelving is the most useful add-on for everyday growing and organization. Beyond that, we usually recommend an exhaust fan, since greenhouses can heat up fast in direct sun—even on mild days. If you plan to grow through winter, you may also want a heater (and a small circulating fan helps a lot, too).
Where does this ship from?
Austin, Texas
How Does Curbside Delivery Work?
Freight delivery drops your crate at the curb/end of driveway. Typically, you’ll unload the contents with the driver and the crate remains on the truck. If you have a forklift or tractor with long forks, you may be able to lower the whole crate using the liftgate. Plan for 2–3 people to help.
Tip: Make sure the truck can access your driveway and you have a clear staging area ready.
Made by
Hoklartherm: 30+ years of craftsmanship
Hoklartherm (KGT) specializes in robust, insulated greenhouses designed for demanding climates. They’re known for engineering that holds up for the long haul, with a clean, modern look that feels right at home in a backyard.
Explore HoklarthermDistributed by
Exaco
Exaco is the authorized North American distributor for Hoklartherm (KGT), known for importing a curated lineup of high-quality European garden products—and for support that goes the extra mile.
More About ExacoReviews
Additional information
| Distributed by | Exaco |
|---|---|
| Door Dimensions | 30″ x 72″ |
| Door Type | Dutch |
| Expandable | No |
| Floorspace | 140 sq ft, 180 sq ft |
| Foundation Frame | Available Separately |
| Frame Color | Black |
| Framing Material | Aluminum |
| Length | 14', 18' |
| Made in | Germany |
| Peak Height | 7′ 7″ |
| R-Value | 2.0 |
| Rainwater Collection | No |
| Roof Glazing | 8mm twin-wall polycarbonate |
| Roof Pitch | 30° |
| Roof Vent Dimensions | 40" x 24" |
| Roof Vent Opener Type | Automatic (wax) |
| Stem Wall Compatibility | Yes |
| Wall Glazing | 10mm twin-wall polycarbonate, 6mm single-wall polycarbonate |
| Warranty | 10 years (prorated after 5 years) on polycarbonate, 15 years on frame |
| Width | 10' |
| Side Wall Height | 5'1" |
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