Sigma Medium Greenhouse

Mid-Size Backyard Kits, 8 ft Wide

4.7 · 90 reviews
Save $400
Sigma 250 (Gen III) greenhouse in a garden setting with trees and flowers
Metal Sigma 250 (Gen III) greenhouse structure in a warehouse setting - Planta Greenhouses EU.
Sigma 250 (Gen III) greenhouse with transparent panels in a warehouse setting
Clear polycarbonate Sigma 250 (Gen III) greenhouse in a garden with flowers and plants around
Sigma 250 (Gen III) greenhouse in a garden with trees and flowers around
Metallic Sigma 250 (Gen III) greenhouse structure in a warehouse setting with shelves and boxes in the background.
Modern Sigma 250 (Gen III) greenhouse with transparent walls and a metal frame, surrounded by greenery.
Metallic Sigma 250 (Gen III) greenhouse with a sliding door in an indoor setting
Sigma 250 (Gen III) Greenhouse in a garden with trees and flowers
Sigma 250 (Gen III) greenhouse with a sliding door in an indoor setting
Metal Sigma 250 (Gen III) greenhouse structure in a warehouse setting
Arc-shaped Sigma 250 (Gen III) greenhouse with a person inside, surrounded by trees and greenery.
Roll of metal sheet on a Sigma 250 (Gen III) greenhouse with a textured background
Interior of a Sigma 250 (Gen III) greenhouse with curved walls and a door.
Interior of a Sigma 200 (Gen III) greenhouse with shelves and a ladder.
Partial view of a Sigma 200 (Gen III) greenhouse with a sliding door
Sigma Medium Greenhouse
Metallic framed door for Sigma 250 (Gen III) greenhouses with a latch mechanism

Sigma Medium 26

Sigma Medium greenhouse kits are arched backyard greenhouses rated for 4.5 ft (55 psf) of snow and 65 mph wind, with 6 mm twin-wall polycarbonate panels and a 10-year warranty. They're for sale in 4 sizes, all 8 ft wide, so you can choose the length that fits your space. Find your greenhouse.

Size: Sigma Medium 26 · 8′ × 26′Size guide
$4,650$5,050Save $400

Free shippingTo nearest terminal
10-year warrantyFrame & panels
Pre-cut panelsFor easier installation
Guided assemblyVideos and live chat
Questions? Talk to a grower.

Mon–Fri 9am–5pm EST or Send a Message

Call us1-877-669-1286

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Which size is best for your garden?

Get this sizing guide with photos and bed layouts.

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  • Insulated Doors NEW – Helps reduce heat loss and drafts, creating a more stable growing environment and improving energy efficiency.
  • Upgraded Door Handles NEW – Smooth, reliable operation with a sturdy grip for easier daily access and long-term durability.
  • Aluminum Polycarbonate Trim NEW – Securely locks panels in place along the arch for added strength, better weather resistance, and a clean, finished look.
  • Window/Door Latch NEW - Makes the door and window open together.
  • Improved Snow Load [NEW] - Rated for a snow load of up to 55 psf (about 4.5 ft of snow).
  • Wind resistant up to 65 mph for those living in gusty climates.
  • Comes with two doors (one at each end).
  • Made with a heavy-duty galvanized steel frame and 6 mm twin-wall polycarbonate panels.
  • Arched shape - helps wind, snow and hail slide off the sides.
  • Extendable beyond 100 ft - so you can expand your greenhouse when you're ready.
  • Maintenance-free means you have more time to focus on your garden.
  • We offer a 10-year warranty because our greenhouse is heavy-duty and long-lasting.
  • Access to our private Facebook group to connect with and learn from other greenhouse owners.
  • The Sigma Medium Greenhouse is available in 4 size configurations. Plus, you may purchase an extension kit, to extend the length of the greenhouse.
  • Extendable & Customizable
  • Snow Load Up To 55 psf 
  • Wind Resistant up to 65 mph
  • We offer a 10-year warranty because our greenhouse is heavy-duty and long-lasting.

Planta Greenhouses s'engage à livrer votre commande rapidement, afin que vous puissiez commencer à utiliser vos produits de serre immédiatement.

Étant donné que les serres sont emballées dans de grandes boîtes, elles ont des exigences d’expédition uniques, notamment :

  • Nous vous contacterons pour confirmer le prix d'expédition, en fonction de votre emplacement et de la taille de votre commande.
  • Les frais de livraison pour la plupart des commandes varient entre 250 $ et 450 $. Les livraisons dans les régions éloignées peuvent entraîner des frais supplémentaires.
  • Lors de votre commande, veuillez indiquer le bon numéro de téléphone et la bonne adresse. Vous serez contacté par téléphone avant l'expédition. Nous déclinons toute responsabilité en cas de livraison à une adresse incorrecte.
  • Dans le cadre du processus de livraison, nous avons besoin d'un numéro de téléphone joignable (pour que la société de messagerie puisse vous contacter) avant que l'article ne soit expédié.
  • Nous mettrons tout en œuvre pour expédier votre commande dans les meilleurs délais et par le moyen de transport que vous aurez choisi. Toutefois, en l'absence d'instructions spécifiques, nous choisirons le moyen le plus rapide et le plus économique. Nous déclinons toute responsabilité en cas de retard de livraison dû à des circonstances indépendantes de notre volonté.
  • Nous n'expédions pas vers des boîtes postales, car dans la plupart des cas, vous devrez signer pour votre article.
  • Le service de livraison haut de gamme n'est pas disponible. Les composants de la serre sont livrés dans plusieurs boîtes, dont la plus grande pèse 36 kg. La serre sera livrée directement à votre entrée. Veuillez prendre les dispositions nécessaires pour que le colis soit transporté jusqu'à son lieu d'installation.
  • Les commandes passées le week-end et les jours fériés seront traitées le jour ouvrable suivant.
Free guide

The Beginner's Guide for Greenhouse Owners

Tell us where to send it and it's yours.

Compare Sigma Medium Greenhouse Sizes

This greenhouse comes in several size configurations. Every greenhouse extends in 6.5 ft sections, so pick the length that fits your plot and your plans.
Sigma Medium Greenhouse Sigma Medium Urban
8′ × 13′
Sigma Medium Greenhouse Sigma Medium 20
8′ × 20′
Sigma 250 (Gen III) greenhouse in a garden setting with trees and flowers Sigma Medium 26
8′ × 26′
Sigma Medium Greenhouse Sigma Medium 32
8′ × 32′
Price
Sale$3,350
$3,150
Sale$4,200
$3,900
Sale$5,050
$4,650
Sale$5,900
$5,400
About
A bed along each side with a center path: greens, herbs and a few tomato plants.
Long side beds and a short bench for seedlings and potted plants.
Room for side beds, trellised crops and a small potting area.
The largest Sigma Medium: several crop zones plus space for benches and a heater.
Width
8 ft
8 ft
8 ft
8 ft
Length
13 ft
20 ft
26 ft
32 ft
Height
7.5 ft
7.5 ft
7.5 ft
7.5 ft
Sq ft
104 sq ft
160 sq ft
208 sq ft
256 sq ft
Owner reviews
4.7 Read all 90 reviews
Read all 90 reviews
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Dome-shaped Greenhouse
About this model

Dome-shaped Greenhouse

Sigma greenhouse has a dome-shaped arch which sheds snow and rain, and the galvanized steel frame with 6 mm twin-wall panels is rated for 55 psf of snow. Insulated doors help keep the warmth in.

pg why planta
Why Planta Greenhouses

Winter-Ready Greenhouses

Heavy-duty greenhouses used by 25,000+ growers since 2019, designed to withstand heavy winters. Backed by a 10-year warranty and live customer support.

pg shipping boxes
Shipping & assembly

Arrives in labeled boxes

Free shipping to the closest terminal in the lower 48. Every panel is pre-cut and every bag of hardware is labeled, so two people can build it with the step-by-step videos.

Questions? Talk to a grower.

Mon–Fri 9am–5pm EST or Send a Message

Call us 1-877-669-1286