Polycarbonate Sigma 300 (Gen III) greenhouse in a garden with flowers and a clear sky
Transparent Sigma 300 (Gen III) greenhouse structure with open doors in a dark indoor setting
Clear polycarbonate Sigma 3x10 (Gen III) greenhouse with glass doors in a garden setting - Planta Greenhouses EU.
Modern Sigma 3x10 (Gen III) greenhouse in a garden setting with trees and flowers - Planta Greenhouses EU.
A detail on the frame of a Sigma 300 (Gen III) greenhouse.
Metallic window of a Sigma 300 (Gen III) greenhouse with visible branding on a dark background
Close-up of a metal frame of a Sigma 300 (Gen III) greenhouse.
Metallic canopy structure of a Sigma 300 (Gen III) greenhouse with a view of a sports field in the background
A side view of a Sigma 300 (Gen III) greenhouse.
A detail of a door handle of a Sigma 300 (Gen III) greenhouse.
Longitudinal view of a large Sigma 300 (Gen III) greenhouse with a metallic frame inside a warehouse.
A detail of a Sigma 300 (Gen III) greenhouse.
Sigma 300 (Gen III) greenhouse with a curved roof and transparent panels in a dark warehouse setting.
Large transparent Sigma 300 (Gen III) greenhouse with metal frame in a warehouse setting
Modern Sigma 300 (Gen III) greenhouse in a garden with trees and flowers
Semicircular Sigma 300 (Gen III) greenhouse with transparent walls and a person inside, set against a natural background.
Metallic door with a reflective surface, of a Sigma 300 (Gen III) greenhouse.
Metallic Sigma 300 (Gen III) greenhouse with a door and window
Close-up of a metallic door hinge of a Sigma 300 (Gen III) greenhouse.
Partial view of a Sigma 300 (Gen III) greenhouse with a curved glass panel and metal frame.
A door closeup of a Sigma 300 (Gen III) greenhouse.
Sigma 300 (Gen III) greenhouse.
A closeup of a Sigma 300 (Gen III) greenhouse.
Clear polycarbonate Sigma 300 (Gen III) greenhouse with metal frame on a dark background

Sigma 3x12

Sigma 3x12

Approx Size: 3 m × 12 m × 2.1 m

Imagine a space in your garden that maintains the right conditions no matter the weather outside. A place where strong winds and heavy snow stay out, while your plants grow safely inside. A calm, productive environment where you can enjoy gardening in comfort all year round.

Features

Strong and spacious: long-lasting construction, weather-resistant materials, and roomy design.

  • 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] - Withstands a snow load of up to 265 kg/m² (55 psf)
  • Wind resistant up to 100 km/h for those living in gusty climates.
  • Comes with two doors (one at each end).
  • Made with a heavy-duty galvanized pipe frame and 6 mm double-wall polycarbonate panels.
  • Arched shape - so the wind, snow, and hail just slide off the sides. 
  • Extendable beyond 30 metres - 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 5-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.
€2.999 EUR
€3.383 EUR Save €384 Sale €2.999 EUR
Have questions? Call us 1-877-669-1286
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Description Reviews Shipping FAQ

About Sigma 3x12

Take your backyard growing to the next level with the Planta Sigma 3×12 (Gen III). Built with heavy-duty materials, this greenhouse is designed for 3 to 4 seasons of cultivation, allowing you to enjoy multiple harvests throughout the year. Its advanced engineering and robust construction deliver the performance of a commercial greenhouse in a clean, functional backyard design.

Sigma 3x10 (Gen III) greenhouse by Planta Greenhouses EU

Exact size: 300cm x 213cm x 1200cm

The rust-resistant galvanized pipe frame means your greenhouse will be standing for years to come. It's tough enough to withstand moderate to extreme weather conditions, allowing your garden to flourish wherever you may live.

The greenhouse comes with:

  • two doors
  • two manual windows
  • the option to install multiple windows.

Stay comfortable and cool throughout the day thanks to the spacious design, tall 2.13-metre roof height, and end-to-end ventilation.

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Snow Load Up To 55 psf (265 kg/m²)
265 kg/m² (55 psf) and is maintenance-free in the winter More About PSF
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Wind Resistant up to 65 mph (100 km/h)
Sturdy greenhouse construction that resists winds up to 100 km/h
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Extendable & Customizable
This greenhouse can be extended with additional expansion kits
 
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Reviews

Shipping

Sigma 3x12 (Gen III) ships in these boxes:

  L, (cm) W, (cm) H, (cm) Weight, (kg) Quantity
Sigma Base 1 210 112 8 26 1
Sigma Base 2 210 112 5 14 1
Sigma Polycarbonate Extension 210 112 5 14 4
Sigma Greenhouse Frame 1 196 45 10.5 36 1
Sigma Greenhouse Frame 2 204 18 10.5 36 1
Sigma Greenhouse Frame 3 196 45 9.5 38 1
Sigma Greenhouse Extension 196 43.5 7 33 4
Total weight: 338

 

Greenhouses are amazing products, and they require special shipping and handling. That is the reason, we have been working diligently over the past year to secure preferential shipping rates for our customers. Shipping prices will be shown on the checkout page based on your address.

  • We will contact you to confirm shipping price, based on your location and order size.
  • Shipping on most residential greenhouse orders is between $250 and $450, customers in remote areas may need to pay extra.
  • When you place your order, please make sure to enter the correct Phone and Address at checkout. You will be contacted by phone before the item is shipped. We cannot be responsible for deliveries to incorrect addresses.
  • As part of the delivery process, we require a contactable telephone number (for the courier company to contact you) before the item is shipped.
  • We do not ship to PO Boxes, as in most cases you will need to sign for your item.  
  • Orders placed on weekends or public holidays will not begin processing until the next business day. 

 

FAQs

Residential Greenhouses

Are there doors on both ends of the greenhouse?

Yes! All of our Sungrow models come with manual doors and a manual window above the door on both ends of the greenhouse.

Do you have lean-to greenhouses?

Unfortunately, we do not have any lean-to greenhouses available at this time.

Do you make custom size greenhouses?

All of our products come pre-packaged by the manufacturer and can only be customized in length (2m extension). However, the height of the greenhouse can also be increased if placed on a base (up to 1.5m above the ground).

How is the greenhouse anchored to the ground?

Every greenhouse kit comes with optional legs that can be dug directly into the ground. The amount of legs included depends on the greenhouse size.

What is the frame made of?

The greenhouse frame is made out of heavy-duty galvanized steel.

What polycarbonate panels are used for residential greenhouses?

We use 6mm heavy-duty, double-walled polycarbonate panels with a UV-protected outside layer for our Residential Greenhouses.

What type of base/foundation is the best for me?

There are several different types of greenhouse bases, information, and pictures posted by our customers on our Customer Stories page and our Planta Facebook page. Additionally, you can learn more about "Types of Greenhouse Bases - With Pros & Cons of Each" on our blog.

FAQs Sigma ventilation window

Can I add windows for my greenhouse later?

Roof ventilation windows work as an add-on and can be installed only once the greenhouse installation is complete. Windows can be added later as well.

How many roof ventilation windows are recommended for the greenhouse?

It is strongly recommended to go with an even amount of roof ventilation windows. This is so you can place at least one on either side of the greenhouse. The amount of windows required depends on the greenhouse size, the climate you are in, and the types of plants that will be grown inside the greenhouse.

FAQs Sigma automatic ventilation window

How do the Automatic Ventilation Windows work?

Our Automatic Ventilation Windows do not require any batteries or electricity. A heat-activated mechanism will open/close the window once a certain temperature is reached.

What are the opening and maximum opening temperatures for the Automatic Windows?

The opening temperature is between 17 °C and 25°C, while the maximum opening is at 30 °C.

Sigma Greenhouses

What are the snow load and wind resistance on the Sigma models?

Sigma models (Gen II) can hold a snow load weight of 160 kg / m2 or 91cm of fresh snow on top of the greenhouse and Sigma models (Gen III) can hold a snow load weight of 265 kg / m2. The wind resistance is 100km/h.

Sigma Installation

Is there support post-purchase?

Absolutely! Our after-sales customer service team is available to answer any and every question. You can fill out our contact form or give us a call at +44 (800) 208-8945.

What resources are available to assist with greenhouse installation?

We offer several resources to help you with the installation process:

  1. Bilt App: Downloadable on the Apple Store and Google Play, it provides digitized step-by-step instructions.
  2. YouTube videos: A series of detailed video tutorials to guide you through the installation process.
  3. Printed Manual: Comes included with your greenhouse.
  4. Blog: Explore our blog for valuable insights such as "Expert Advice: 9 Tips For Installing Sungrow Greenhouses With Ease!"
  5. Customer-Only Facebook Group: Connect with other customers for valuable installation tips.

If you still need assistance, our customer service is ready to help via phone or email.

What type of base/foundation is the best for me?

This can vary depending on your location, gardening plans, and desired aesthetic. To better understand the different options available, you can find several different types of greenhouse bases, information, and pictures posted by Planta Greenhouse owners on our Customer Stories page and our Planta Facebook page. Additionally, you can learn more about it on our Greenhouse Bases blog.

Customization Options

Can I add my own vents, fans, heaters, and lights?

Of course! The polycarbonate is very easy to work with, and the galvanized steel frame is strong enough to support any additional accessories.

Can I get a longer greenhouse?

Most of our residential and commercial greenhouses are extendable up to 30 metres. Learn more about our extension kits for both the Sungrow and Sigma models.

How can I customize my greenhouse?

The customization possibilities are truly endless with a Planta Greenhouse. To help you get started, take a look through “16 Ways to Supercharge Your Greenhouse” on our blog.

Is hanging plants, heaters, and hammocks safe from my greenhouse frame? How much weight does it handle without affecting the guarantee?

It is safe to hang plants and accessories on a Sungrow greenhouse since each internal reinforcement arch can withstand up to 45.3 Kg. On the Sigma series, you can pre-drill the holes on the framing and hang small things. We would not suggest hanging anything heavier than 2.2 – 4.5 Kg per arch.

May I heat my greenhouse with fire pits or similar?

You can use any heating source inside, like electricity, gas, propane, and even wood. It may be tricky to heat with wood, as you want to ensure that you keep the stove/pit away from the panels to prevent them from melting or burning if they are too close to the fire source. In this case, the customers ideally would want to come up with an exhaust system, making sure it’s not in contact with the panels, for being a flammable material.

May I heat my greenhouse with firepits or similar?

You can use any heating source inside, like electricity, gas, propane, and even wood. It may be tricky to heat with wood, as you want to ensure that you keep the stove/pit away from the panels to prevent them from melting or burning if they are too close to the fire source. In this case, the customers ideally would want to come up with an exhaust system, making sure it’s not in contact with the panels, for being a flammable material.