Front view of the Riga Greenhouse with an open door

Features

Feature image pointing out the snow load and wind rating of the Riga Greenhouse

Feature image pointing out the thickness of the twin-wall polycarbonate of the Riga Greenhouse

Riga Greenhouse

Name: Riga Greenhouse
Brand: Hoklartherm/KGT
SKU: 570
Availability: InStock

Price range: $5,864.00 through $7,819.00

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Features

Built for harsh weather: 120 mph wind rating (3-second gusts) + 30 psf ground snow load
Gothic-arch design helps shed snow and handle wind more naturally
Insulated performance: 8mm & 10mm twin-wall polycarbonate paired with rubber seals for steadier temps in colder seasons
Made in Germany with tight-fit construction for a solid, long-term structure
Smart cross-breeze setup: Dutch door + rear wall window lets you vent heat effortlessly while keeping critters out
Automatic roof vent opener(s) included for hands-free passive venting as temps rise
Right-sized for serious gardeners: not too small, not too big

What's Included

Frame + glazing + hardware
Roof vents with auto openers(qty varies by size)
Lockable Dutch door (+ keys)
Rear window with manual opener

Dimensions

Available in 3 sizes:

Riga 3: 9′ 8″ W x 10′ 6″ L x 7'7" H
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
Structural Certification: Download here
Warranty: 10 years on polycarbonate (prorated after 5 years), 15 years on frame

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Description

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The Riga is a gardener-first greenhouse built for real weather—windy days, cold snaps, and heavy winter conditions. Its gothic-arch shape and tight-fit construction create a structure that feels solid, not flimsy.

You get insulated twin-wall polycarbonate (10mm walls and 8mm roof) designed to hold steadier temperatures, plus a ventilation setup that’s practical for daily growing. If you want a greenhouse that stays put, stays warm, and stays quiet in the wind, this is one of the strongest all-around options in its size class.

Made for Rough Weather

Riga is designed around stability: the gothic-arch profile helps snow shed more naturally and reduces wind stress on the structure.

With a 120 mph wind rating (3-second gusts) and 30 psf ground snow load, it’s built for gardeners who don’t want to baby their greenhouse every time the forecast looks ugly.

Insulated Panels That Hold Steadier Temps

The Riga uses 10mm twin-wall polycarbonate walls (gable ends) and an 8mm twin-wall roof, which helps reduce temperature swings compared to thin, single-wall coverings.

That insulation makes a noticeable difference for cold-season growing—especially on cold winter days when you want warmth to stay inside longer (R-value: 2.0).

Tight-Fit Build (Quiet, Secure, No Rattling)

A tight-fitting greenhouse isn’t just about insulation—it’s about how it behaves in real wind. Riga’s precise construction and rubber seals keep the panels snug, so you don’t deal with rattling panels or sections shifting around over time. It’s the “solid feel” difference that budget greenhouses often don’t have.

Better Polycarbonate (Built to Stay Clear)

Not all polycarbonate ages the same. Riga uses UV-protected twin-wall panels designed to resist the common issues people complain about—yellowing, brittleness, and cloudy-looking panels over time. If you’ve seen budget polycarbonate greenhouse panels degrade quickly, this is a big reason the Riga is in a different category.

Fast Venting When You Need It

Riga’s airflow setup is simple and effective: roof vent(s) with automatic wax openers plus a rear wall window and Dutch door for quick manual control. On warm days, that cross-breeze setup makes it easy to dump heat fast—without leaving the greenhouse wide open to pests.

Right-Sized for Serious Gardeners

Riga is a sweet-spot footprint for growers who want real usability without jumping into “commercial-sized” territory. You get a consistent 9’8″ width, with length options that scale from 110 to 180 sq ft, so it’s easier to match your space and your growing plans.

If You Need Smaller or Bigger

If this size range isn’t quite right, the Riga family has two close neighbors:

Riga S: Just like this line but more compact for tighter spaces

Riga XL: a larger, more insulated line with 16mm triple-wall polycarbonate for even stronger cold-weather performance

Add-Ons & Upgrades: Make it your own

Shelving

Add a full-length seed tray 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″)

Foundation Frame

If you want an easy way to anchor the Riga Greenhouse without a concrete or wood foundation, add this foundation frame. All you need is digging a trench that this frame sits in.

Gallery

Quick Size Guide

Peak height: 7’7″

Sidewall height (curve): 6′ 1″ high near shelves

Roof pitch: 17°

Size	Actual Dimensions	Floorspace
Riga 3	9′ 8″ W x 10′ 6″ L	110 sq ft
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
8mm twin-wall polycarbonate for the roof, 10mm twin-wall polycarbonate for the gable ends
Lockable Dutch door (30″ x 72″)
Rear wall window (30″ x 42″)
Wedge seals
Hardware

Vent Type	Dimensions	Riga 3	Riga 4	Riga 5
Roof Vent + Auto Opener	40″ x 24″	1	2	4

Specifications

Brand	Hoklartherm/KGT
Distributed by	Exaco
Made in	Germany
Width	10'
Length	11', 14', 18'
Floorspace	110 sq ft, 140 sq ft, 180 sq ft
Peak Height	7′ 7″
Side Wall Height	6′1″
Framing Material	Aluminum
Frame Color	Aluminum
Roof Glazing	8mm twin-wall polycarbonate
Wall Glazing	10mm twin-wall polycarbonate
Roof Pitch	17°
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
Wind Rating	120 mph
Snow Tolerance	30 psf (ground-snow load)
Rainwater Collection	No
Stem Wall Compatibility	Yes
Expandable	No
Warranty	10 years (prorated after 5 years) on polycarbonate, 15 years on frame

Q&As

Still have a question?

Send us your question

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 Hoklartherm

Distributed by

Exaco

Exaco is the authorized North American distributor for Alton, known for importing a curated lineup of high-quality European garden products—and for support that goes the extra mile.

More About Exaco

Additional information

Distributed by	Exaco
Door Dimensions	30″ x 72″
Door Type	Dutch
Expandable	No
Floorspace	110 sq ft, 140 sq ft, 180 sq ft
Foundation Frame	Available Separately
Frame Color	Aluminum
Framing Material	Aluminum
Length	11', 14', 18'
Made in	Germany
Peak Height	7′ 7″
R-Value	2.0
Rainwater Collection	No
Roof Glazing	8mm twin-wall polycarbonate
Roof Pitch	17°
Roof Vent Dimensions	40" x 24"
Roof Vent Opener Type	Automatic (wax)
Side Wall Height	6′1″
Snow Tolerance	30 psf (ground-snow load)
Stem Wall Compatibility	Yes
Wall Glazing	10mm twin-wall polycarbonate
Warranty	10 years (prorated after 5 years) on polycarbonate, 15 years on frame
Width	10'
Wind Rating	120 mph

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