The Sigma 3x8 (Gen III) was designed with a focus on spaciousness and stability. This greenhouse is perfect for 3 or 4 seasons of growing, allowing you to harvest fresh fruits and vegetables well into the colder months. Our Sigma greenhouses are built to last, featuring a rounded design and creative construction that brings heavy-duty greenhouse engineering into your own backyard.
Exact size: 300cm x 213cm x 802cm
The end-to-end airflow, spacious size, and high 2.13-metre roof height make this a comfortable place to garden throughout the day.
The greenhouse comes with:
The galvanized pipe frame is both rust-resistant and durable. In addition, the construction can withstand moderate to extreme weather conditions, ensuring your garden will stay safe and flourish throughout the seasons.
We love our sigma greenhouse, it has kept our garden going during this winter. We installed a wood stove inside it! and the pipe did not destroy the poli! We are super happy with this greenhouse, we are planning on expanding it or buying a bigger one. I highly recommend this greenhouse, money very well invested! We live in Idaho for reference.
Thank you so much, Diana! We're thrilled to hear how well your Sigma 32 is performing through the Idaho winter. It's fantastic that you were able to install a wood stove and that the poly held up beautifully. Your experience keeping the garden going through winter is incredibly valuable feedback and will be so helpful for other growers in similar climates.
Thank you for the wonderful recommendation and for sharing how well your investment has paid off. Here's to many more successful growing seasons ahead!
The Booklet Instructions do not match the sequence of the video instructions which required rework.
I had lots of problems getting the end panel polycarbonate panels to line up properly, partly because the screw holes were correctly drilled on the bottom of the frame. The polycarbonate end panels should be installed after the doors and windows are installed.
The booklet instructions has you install the doubled-sided tape to the end of the polycarbonate panels, but the video shows installing the tape to the profile which works lot better. It should be only installed to one side of the profile which make installing much easier.
I could not get the panels on one end to line up correctly with the profile. I fought with it several hours, but it would not line up correctly. The one end fell right in place. I should have started from that end first.
The greenhouse is built very strong.
Hi Carl,
Thank you for taking the time to share your detailed feedback and for the 4-star review! We really appreciate you highlighting both the challenges you faced and the positive aspects of your Sigma Urban.
We understand how frustrating it can be when instructions don't align perfectly, and we're sorry the booklet and video sequences caused confusion and extra work during your build. Your insights about the double-sided tape application and the order of installing end panels versus doors and windows are incredibly valuable — we'll definitely pass these along to our product team for future improvements.
It sounds like you discovered some helpful techniques along the way, especially regarding the tape placement on the profile rather than the panels. These kinds of real-world insights from experienced builders like yourself help us improve the process for future customers.
We're glad to hear that despite the assembly challenges, you found the greenhouse to be built very sturdily. That's precisely what we aim for with our structures.
Thanks again for your patience during the build and for sharing your experience!
We installed our Sigma greenhouse with an extension in 2022, making it 20 feet long—plenty of room for our growing needs and winter refuge. In the frigid Chicago climate, our Planta Greenhouse has been nothing short of a game changer. We use it to protect perennials like palm trees, bird of paradise, lavender, eggplant, peppers, crotons, tradescantia, geraniums, and elephant ears—especially the ones that can’t stay indoors due to our cats. All the pet-safe plants stay in the house, and everything else thrives inside the greenhouse. We also get a two-month head start on our annuals, which is huge for Chicago gardening. As of early February, we already have peppers, tomatoes, daisies, petunias, cosmos, morning glories, cucumbers, and forget-me-nots started.
Our greenhouse has become our favorite place to be. We spend all winter inside, soaking up the sun while it's freezing or snowing outside. It’s our little haven—a space for plant care, self-care, and memory-making. In fact, it became so special that Marcin proposed to me right there in the greenhouse. Of course, I said YES!
We added electric to the structure to make year-round use possible, and we installed a propane space heater for the coldest weeks. Two 65-gallon water jugs provide all the irrigation we need through winter. A compost bin adds warmth and allows us to reduce waste, and we’ve included shelves with grow lights to supplement sunlight. We also have a dedicated seed-starting station at the front of the…
For years, owning a greenhouse had been a dream of ours—and now it’s become a key part of how we live and grow. The greenhouse works in tandem with our outdoor garden to supply nearly all of the produce we consume. Once the colder months arrive, we transition entirely to greenhouse-grown food, eliminating the need to buy from the grocery store.
Inside, we grow tomatoes, potatoes, peppers, beets, carrots, leeks, peas, string beans, broccoli rabe, kale, lettuce, mustard greens, basil, mint, eggplant, strawberries, and even lemon and fig trees, which we move in during winter along with our hibiscus and blueberries. It’s glorious watching everything thrive, even in below-freezing temperatures. The greenhouse has become our winter escape and has even protected many plants during hurricane season and high winds.
Our buying experience was seamless—we didn’t even need to contact customer service. Reading customer stories from people in similar climates was incredibly helpful and gave us the confidence to move forward.
We customized our setup by building the greenhouse on a 4x4 wood foundation attached to concrete footings, giving us an extra foot of interior height. Inside, we added raised beds, a pebble stone walkway, and sealed all seams with silicone for extra insulation.
What we love most is the beautiful retro vibe of the greenhouse, paired with its sturdiness—it’s already held up to 50 mph winds without any issues. As we continue to learn and grow, we’re also exploring…
We purchased our Sigma 20 greenhouse from Planta in 2022, and it arrived within a week—even before we had finished building our foundation! As new greenhouse owners and gardeners, we've really enjoyed experimenting with a variety of plants inside: peppers, cucumbers, tomatoes, herbs, and even a surprise squash that popped up by accident.
Our Planta Greenhouse has helped us extend our growing season and complement our outdoor garden. It’s been so rewarding to move toward year-round growing. To support that, we’ve added a fan for airflow and some LED lighting to keep things thriving even as the days get shorter.
One of our absolute favorite things? Enjoying a hot cup of coffee inside the warm greenhouse on a frosty January or February morning—it honestly feels like a mini vacation. We'd love to add an extension someday (we already built the foundation to fit it)!
| 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 | 2 |
| 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 | 2 |
| Total weight: | 244 |
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.
