Customizable Footprint
Tailor the size up to 20 ft wide and 60 ft long. It gives you room for larger plant collections, dedicated pathways, work benches, and future expansion.
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ExacoJanssens
Exaco Janssens Gigant Large Greenhouse
$42,999
$51,995
Save $8,996
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Product Details
The Gigant Large is our biggest glass greenhouse, built for growers and hosts who've outgrown a standard kit. Expect a soaring peak, oversized aluminum framing, and portal-frame reinforcement throughout, wrapped in a true glass silhouette that reads more like a garden room than a grow box.
What’s Included
Every Gigant Large ships complete: aluminum framing reinforced with portal frames, your choice of glazing, a double hinged entry door, decorative ridge cresting, and a mixed roof vent package pairing automatic openers with manual roof and side vents for balanced airflow. Rain gutters with dual downspouts are included on both eaves.
Technical Specifications
Framing is 17-gauge black aluminum, with roof glazing available in 10mm twin-wall polycarbonate or 4mm tempered glass and 4mm tempered glass on the walls either way. Roof pitch runs 22°, sidewall height is 6'8", and automatic wax-motor openers come standard on the roof vents. Full dimensional breakdowns live in the Specs tab above.
Installation & Manuals
Each kit ships with detailed, step-by-step assembly instructions. Polycarbonate panels are noticeably lighter than glass, which makes for an easier build; if you go with the all-glass roof, plan on an extra set of hands for the panels. Most owners budget a weekend with a 2-3 person crew and basic hand tools. Prefer to leave it to a pro? Use the zip code lookup above to find an installer near you.
Delivery & Prep
This ships as a large freight delivery via semi-truck, curbside, typically within 8-13 business days. You'll want a clear, level unloading area and a plan for moving the crated panels and framing to the build site — a hand dolly or a couple of extra people makes this much easier. Have your foundation or base prepped before delivery so you can move straight into assembly once it arrives.
Warranty & Returns
The Gigant Large is backed by a 15-year limited warranty on the frame, so you're covered well beyond the first few seasons. If anything ever needs attention, our team handles claims directly — just call or text us and we'll walk you through it.
Gigant Features
Elevate Your Growing Space
The Gigant Large pairs a soaring 10'10" peak with oversized 17-gauge aluminum framing and internal portal-frame reinforcement, giving you a true glass room built for serious growing or everyday living space.
Tall Wall Heights
Choose wall heights from 6'8" to 9'7". The height makes it easier to move, grow taller plants, and create a spacious greenhouse.
Belgian-Engineered Construction
Janssens has spent 75+ years perfecting European greenhouse design in Belgium. Every Gigant Large uses 17-gauge aluminum framing with internal portal frames for extra rigidity, backed by a 15-year limited warranty.
Black Aluminum Frame
Gives the greenhouse a clean, elevated look while helping protect against rust, rot, and outdoor wear.
Double Hinged Doors
Make it easier to bring in plants, pots, soil, tools, and supplies without awkward lifting or tight entry points.
Superior Ventilation
Six roof windows and four louvre windows help move fresh air through the greenhouse and support better climate control.
Built-in Details
Designed for airflow, drainage and everyday use
Built-in systems that help with ventilation, watering, and long-term performance.
Six roof vents
Help release hot air through the top of the greenhouse for better temperature control.
Louvered window
Supports cross-ventilation by bringing cooler air in from the side of the greenhouse.
Built for Long-Term
17-gauge aluminum adds strength, while rubber seals reduce drafts and rattling.
Compare models
Compare Janssens Greenhouse
Find the Jannsens Greenhouse that fits your space, growing goals, and budget.
Jannsens Gigant Large Greenhouse
From $42,999
- Dimensions 17'5" x 27'1"
- Grow Space Approx. 472 sq. ft.
- Doors Double Hinged
- Roof vents Variable
- Louvered window Variable
- Misting system Included
- Best for Large plant collections
Jannsens Victorian Junior Greenhouse
From $7,999
- Dimensions 7'9" W x 10'2", 12'6", 15’
- Grow Space 79, 96, or 116 sq. ft.
- Doors Single sliding
- Roof vents 1-2
- Louvered window Optional additional
- Misting system Not Included
- Best for Small backyard
Jannsens Modern Greenhouse
From $17,249
- Dimensions 7'9" x 10'2", 10'2" x 15', or 10'2" x 19'11"
- Grow Space Approx. 79, 150, or 200 sq. ft.
- Doors Double hinged doors
- Roof vents 2-3
- Louvered window 1-2 included
- Misting system Not Included
- Best for Growing lounge setups
15-year Janssens frame warranty
Every Royal Victorian greenhouse is backed by Janssens' 15-year frame warranty, with durable powder-coated aluminum construction made for long-term outdoor use.
Specifications
Gigant Large specs at a glance
A quick look at the key dimensions, materials, included systems, and warranty details for the Gigant Large Greenhouse.
Dimensions
13ft x 13ft to 20ft x 60ft
Growing space
Approx. 472 sq. ft.
Entry width
56 3/4"
Sidewall height
8'3"
Peak height
12'
Install clearance
21'5" x 31'1"
Frame material
Powder-coated aluminum
Glazing
4mm tempered glass
Snow load
30 lbs / sq ft
Wind load
100 mph
Ventilation
4 roof vents included
Door system
Double hinged glass door
Foundation
Aluminum base kit
Warranty
15-year limited
Optional Additions
Build out your Gigant for the way you grow
Additions can help tailor your greenhouse to your needs.
Our team can help you choose what makes sense for your setup.
Cooling and airflow
Shadecloth, exhaust fans, and fly screens can help manage heat, airflow, and pests.
Growing and storage
Seed trays, shelves, and work surfaces help organize plants, tools, and supplies.
Entry and access
Threshold, door, ramp, and stem wall options can make entry easier based on your site.
Seasonal growing
Heaters, thermostats, and winter covers can help support colder-weather growing.
Planning Ahead
Prepare Your Site Before Your Gigant Greenhouse Arrives
The Gigant is a large-scale greenhouse built for serious growing, so the right prep matters. Before delivery, plan for the foundation, anchoring, site clearance, water access, and installer support to make setup smoother from day one.
Foundation prep
The Gigant is a substantial structure, so its foundation deserves real planning. We recommend a poured concrete slab or continuous footing that's level, square, and sized to match the greenhouse's exact footprint, since even a small twist in the base can throw off door swing and panel fit later on. Grade the site so water drains away from the structure, and in colder regions, build below the frost line to prevent seasonal shifting. Want extra headroom or a raised look? The Gigant also supports a stem (knee) wall foundation built from concrete block or another moisture-resistant material, which lifts the frame off the ground and adds interior height while protecting the base from moisture. Our team is happy to talk through foundation specs with you before delivery.
Anchoring
Once your foundation is in place, proper anchoring is what keeps the Gigant steady through wind, snow, and everyday use. The frame's oversized aluminum profiles and internal portal-frame supports already build in serious rigidity, engineered to hold up against winds up to 120 mph and ground snow loads up to 25 PSF. Securing the base to your foundation with the recommended anchor bolts and hardware ties that strength directly into your site. Let us know your region's wind and snow conditions during planning, and we'll help you choose the right anchoring approach so your greenhouse stays put for the long haul.
Water and power
Plan utility runs before your site is finished. Coordinate with your electrician and plumber to bring water and power to the greenhouse footprint.
DIY & Installer support
Whether you're a confident DIYer or prefer to hire a professional, we'll help you find the right path and connect you with vetted installers.
Need help planning ahead?
We can help you think through foundation, utilities, delivery access, and installer support before your greenhouse ships.
Delivery
What to expect when your greenhouse ships
Before delivery, you’ll receive tracking details and guidance so you know what’s coming, where to place it, and how to store the parts before assembly.
Freight delivery
Your greenhouse ships by LTL freight and is delivered curbside. Greenhouses typically arrive in about 8 to 13 business days, including packing and transit time.
Plan for large crates
The Gigant arrives on a 1,440 lb glass pallet (90" tall, 40" x 48" base) plus two long cartons for the frame and components, so it's important to plan enough space for drop-off.
Unload safely
The driver will unload the glass pallet with a liftgate and pallet jack. You'll want help available for the long cartons and moving parts after delivery.
Store parts dry
Store the greenhouse components in a garage or dry covered area until assembly. Keeping everything dry helps protect the frame, packaging, and glass.
Frequently Asked
Quick answers around choosing, ordering, delivery, and setup.
The Gigant works well for serious growing, large plant collections, crop production, overwintering, garden-room use, and custom greenhouse setups.
Every Gigant ships with the aluminum frame, your chosen glazing, ridge cresting, a double hinged door, and the roof and side vent package shown in the Specs tab, plus the hardware and instructions needed for assembly. See the Specs tab above for the full breakdown.
Sidewall height runs up to 9'7", and the 22° roof pitch carries the peak up to 12' at its tallest — tall enough for hanging baskets, tall tropicals, or a real garden-room feel. Check the Specs tab above for exact numbers on your chosen size.
Yes. The Gigant supports a range of optional additions — including shelves, shade cloth, and fans — so you can tailor it to your setup at any time. Explore the add-ons above to build out your greenhouse.
The Gigant is Janssens' largest model — a taller peak, oversized 17-gauge aluminum framing with portal-frame reinforcement, and a double hinged door built for wide, easy access. Compare it side-by-side with the Junior and Modern Greenhouse in the Compare tab above to see how the sizes and features stack up.
Yes. Built with durable powder-coated aluminum and backed by a 15-year frame warranty, the VI46 is made for long-term outdoor use. With added insulation and optional heating, it supports growing through cold-weather months.
Our greenhouses use rust-resistant aluminum frames paired with tempered safety glass or twin-wall polycarbonate, so they stay durable and beautiful through every season.
Absolutely. With proper insulation, ventilation, and optional heating, our greenhouses support growing through every season.
Most greenhouses can be assembled over a weekend with two people. Larger models may take a little longer, and clear step-by-step guides are included with every kit.
Yes. A level base such as a concrete slab, paving, or a purpose-built base kit keeps the structure stable and square over its lifetime.
We offer free curbside freight delivery on greenhouse orders within the contiguous US. Any surcharges for remote areas are shown clearly at checkout.
In-stock greenhouses typically ship within 3–5 business days, with freight delivery arriving 1–2 weeks later depending on your location.
Our greenhouses are backed by manufacturer warranties, including up to a 15-year warranty on Janssens frames. Full coverage details are listed on each product page.
Reach out with your order number and a quick photo, and we'll arrange a replacement part right away at no cost for qualifying issues.
Financing Now Available!
Explore low-rate financing options for qualified customers, including greenhouse structures, accessories, and foundation costs.
Need help planning?
Not sure which model, size, glazing, or setup makes sense for you? Our team can help you compare options, plan your site, and understand the steps before you order.
