Rion Grand Gardener 8x12
$4,099· Nov 12, 2026
8'9" x 12'8" · 110.8 sq ft · 4 mm roof, 6 mm walls

The thickest panels on our list, an 8 ft 10 in peak and everything you need in the box.
At a glance: size, peak height, warranty
Free curbside freight delivery to the 48 contiguous states (Planet Greenhouse).
The Glory is our No. 1 because it is the only kit here with 10 mm twin-wall polycarbonate on every side, and it comes with the steel base, two automatic roof vents, a louver window and gutters already in the box. You pay for that: $4,349 at Planet Greenhouse on November 12, 2026, about $45 per square foot. If you grow through a real winter and want to buy once, it is the safest pick here.

Most kits in this price range use 4 mm or 6 mm twin-wall sheets. The Glory doubles that on every face. Twin-wall means two skins with an air gap between them, and a thicker gap holds heat better on a still, frosty night. In practice that is the difference between a greenhouse that is only frost-free with a heater running hard and one where a small heater ticks over. Dealer specs put light transmission at 79%, diffused, which is a little lower than the 82% of the 4 mm Palram kits. Diffused light is kind to seedlings: no hard shadows, fewer scorched leaves in July.
The frame is a reinforced aluminum one in charcoal gray. Planet Greenhouse lists the kit at 20 lb/ft² of snow and 60 mph of wind. Those are honest, middle-of-the-road numbers. In heavy-snow country you still brush the roof after a big storm.
The roof peaks at 105.5 in, so 8 ft 10 in, and the walls rise to 75.1 in before the roof starts. That second figure matters more than people think: with a low eave, you can only stand up straight in a strip down the middle. Here you can work at a bench along the side wall without ducking. The 31.7 in door with its threshold ramp takes a wheelbarrow, and at 95.6 sq ft you get room for two benches and a center path, or one bench and a row of tomatoes in the ground.
This is where the price starts to make sense. Two roof vents with automatic openers, a side louver window, a galvanized steel base with a ground anchoring system, rain gutters and plant hangers are all included, per Planet Greenhouse. On cheaper kits those are add-ons, and each one is another order and another weekend. Palram-Canopia says no special tools are needed. Plan on two people and a level spot.
Planet Greenhouse, a US dealer, listed it at $4,349 on November 12, 2026, with free curbside freight delivery to the 48 contiguous states. Palram-Canopia does not sell this kit online in the US, so we link to that dealer. The 10-year limited warranty is the longest of the Palram kits we compared; the others carry five years.
The catch: At $45 per square foot it costs more than twice the YourGreenhouses Polycarbonate per square foot, and its 20 lb/ft² snow rating is below the 32 to 38 lb/ft² the YourGreenhouses tunnels publish.
| Price | $4,349 at Planet Greenhouse, checked November 12, 2026 |
|---|---|
| Footprint | 8' x 12' · 95.6 sq ft |
| Price per square foot | $45.49/sq ft |
| Panels | 10 mm twin-wall polycarbonate on the roof and all walls |
| Light | 79% light transmission (dealer spec table), diffused |
| Frame | Gray powder-coated aluminum frame, reinforced (Canopia: "extra-thick") |
| Peak height | 8'10" (105.5 in) |
| Eave (wall) height | 75.1 in |
| Door | Heavy-duty lockable door, 31.7 in wide, with threshold ramp |
| Snow load | 20 lb/ft² of snow (Planet Greenhouse) |
| Wind rating | 60 mph (dealer spec table) |
| Ventilation | Two roof vents with automatic openers plus a side louver window |
| Base | Galvanized steel base and ground anchoring system included (Planet Greenhouse) |
| Gutters | Included |
| Warranty | 10-year limited warranty (Palram-Canopia, per the dealer and canopia.com). |
| Assembly | DIY kit, no special tools needed per Palram-Canopia; plan on two people. |
| Delivery | Free curbside freight delivery to the 48 contiguous states (Planet Greenhouse). |
| Model / SKU | HG5612 (Canopia model #702208) |
Each criterion is scored out of 10 from the published figure; anything not published scores 2. Full method.
| Price per square foot (dated, US) (20%) | 4.2/10 |
|---|---|
| Panels: insulation and thickness (20%) | 9.5/10 |
| Published snow load (15%) | 7.5/10 |
| Warranty (15%) | 8.5/10 |
| Published wind rating (10%) | 7.2/10 |
| Headroom (peak height) (10%) | 9.9/10 |
| Ventilation in the box (5%) | 10.0/10 |
| Base or anchoring in the box (5%) | 10.0/10 |
$4,349 at Planet Greenhouse on November 12, 2026 (Planet Greenhouse product page (US dealer)).
Free curbside freight delivery to the 48 contiguous states (Planet Greenhouse). 10-year limited warranty (Palram-Canopia, per the dealer and canopia.com).
Palram-Canopia doesn't sell online in the US, so we link to Planet Greenhouse, a US dealer.
$4,099· Nov 12, 2026
8'9" x 12'8" · 110.8 sq ft · 4 mm roof, 6 mm walls
$3,372.97$6,132.67· Nov 12, 2026
9'11" x 13'2" · 129 sq ft · 6 mm polycarbonate
$2,810· Nov 12, 2026
8.2' x 13' · 106.6 sq ft · 6 mm polycarbonate
Every price was read on November 12, 2026 on the maker's or dealer's own page.
Eight criteria, the same for every kit. What isn't published scores low.
Tell Megan Hollis your yard, your winters and your budget; she answers.