A sturdy high tunnel greenhouse with generous protected growing space for vegetables, seedlings and a longer gardening season

Our Bloomcabin Polycarbonate High Tunnel Greenhouse creates a spacious, permanently sheltered place to grow vegetables, seedlings and heat-loving crops. Its 3 m-wide tunnel shape leaves room to arrange beds, a working path and watering sensibly. Instead of flexible film, 6 mm polycarbonate panels form a fixed cover on the galvanized steel structure.

The standard length is 4 m and can be adapted with compatible extension sections as your growing space needs change. The galvanized steel frame is anchored through its arches into the ground. Combined with the permanently fitted polycarbonate cover it provides a stable, protected growing environment. Explore our greenhouses and conservatories and our guides and planning advice.

More permanent protection than a basic film tunnel, with more growing room than many compact garden greenhouses

This model suits gardeners who intend to use the space regularly for vegetables and plants. It accommodates permanent beds and working paths, while the selectable length can still be matched to the property and the area you genuinely need to manage.

Key details for the Bloomcabin High Tunnel Greenhouse

Width: 3.00 m.

Height: 2.10 m.

Length: Standard model 4 m; extensions in 2 m increments.

Frame: Galvanized steel, 1 mm material thickness.

Profile: Omega profile, 56 mm wide.

Arch spacing: 1 m between arches.

Snow load: 210 kg/m².

Ground anchoring: Each arch extends approximately 35 cm into the ground.

Cover: 6 mm UV-protected polycarbonate.

Access: 1 door at the front.

Ventilation: 2 side windows for temperature control and air exchange.

Warranty: 12 years under the applicable warranty terms.

1 front door and 2 side windows make access and climate management easier

The interior height supports comfortable upright work and taller crops such as tomatoes or cucumbers. Use the front door as the main entrance. Keep the space immediately behind it clear so watering cans, harvest containers and garden tools can move in and out without damaging plants.

Keep the 2 side windows accessible from inside and outside. Position plants, supports and stored items so the windows can be operated fully. When planning beds, make sure the windows remain reachable once crops have matured.

Open and close the door and windows regularly to confirm they operate correctly. Remove soil and plant debris from moving areas. If a component binds, investigate the cause rather than forcing it.

Place crops for short working routes and easy access

When laying out the interior, consider more than crop type: account for plant height, monitoring needs and harvesting frequency. This helps make sensible use of the available space while keeping every crop accessible.

Consider the site, ground conditions and future use before installation

Measure the footprint for the chosen tunnel length and prepare as level a surface as possible. Leave adequate working space around the structure to position arches and polycarbonate panels safely. Plan surface-water drainage as well: runoff from the fixed cover should not collect around the structure or in front of the door.

Because the arches extend approximately 35 cm into the ground, establish the location of buried electrical, water and drainage services before work begins. Remove large stones and other obstacles before assembly rather than during it. On uneven ground, prepare the area so all arches stand on the same line and can reach the intended installation depth.

Plan how the components will travel from the delivery point to the prepared site. Keep the route clear during assembly; soil, compost and garden tools should not obstruct the work area. After installation, both long sides also need to remain accessible from outside for inspection and maintenance.

Find further planning and ordering information in our guides and planning advice.

When is a high tunnel a better fit than a traditional aluminium greenhouse?

A traditional aluminium greenhouse offers clean-lined styling, varied design options and can become a visible feature in the garden.

The high tunnel instead prioritizes a large continuous growing area, robust construction and the option of modular expansion.

Choose the high tunnel when productive, sheltered growing area matters most. A traditional greenhouse may be the better choice when a straight-edged form and visual integration with the garden take priority.

Adapt use and care to your site and local weather patterns

Canadian gardening conditions can vary greatly by region and even by property. Coastal sites may bring wind, damp air and rapidly changing weather, while more sheltered or continental locations can experience hot summer days and colder winters. Use the high tunnel in response to your garden’s microclimate rather than a fixed calendar.

For early crops, the sheltered space can provide a useful head start in spring. Later in the season, heat-loving plants benefit when rain and wind reach their leaves and fruit less directly. Harvests can often continue later into fall while light and temperature remain sufficient.

During the first season, note unusual temperature patterns, extended damp spells and areas where plant growth is weaker. These observations will help you refine the crop layout and care routine for the following year.

Select a sunny site and leave room for air movement

A sunny location is particularly valuable in spring and fall. Observe when buildings, hedges and trees cast shade over the intended area. Leave enough clearance from obstacles for the 2 side windows to ventilate effectively.

At exposed sites, observe the prevailing wind direction and avoid unnecessary wind channels between buildings. Natural shelter at a suitable distance can help, but it must not permanently shade the tunnel or block air circulation.

Also plan for ongoing care when choosing the location. The front door should be easy to reach, and enough room should remain along both sides to inspect windows, polycarbonate panels and fasteners externally.

Organize tomatoes, cucumbers, peppers and early greens across the 3 m width

The fixed 3 m width works well for 2 side beds with a central working path or 3 narrower growing zones. Position tall crops such as tomatoes and cucumbers so they do not needlessly shade lower plants. If you use strings or supports, plan their attachment before planting.

In spring, lettuces, kohlrabi, radishes, herbs and seedlings can occupy the protected area before warm-season crops take over. After the main season, part of the tunnel can be used again for hardy leafy vegetables or late herbs.

Label planted bed sections and record what grew in each area. This simplifies planning the next planting without needing to reorganize paths or ventilation zones.

Respond early on hot days before heat and humidity build up

Inside a closed tunnel, temperatures can rise quickly on sunny days. Open the side windows before plants show signs of heat stress where conditions allow. Early ventilation moderates temperature peaks and moves moist air out of dense plant growth.

For tomatoes especially, it is helpful to keep leaves as dry as possible and avoid encouraging condensation. Ventilate on mild days too when outdoor air permits good exchange. After watering, excess moisture should be able to leave the crop canopy.

During longer hot periods, adjusted watering times and temporary shade where needed may help. The appropriate approach depends on the region, orientation and crop density.

Bring water to the roots instead of humidifying the whole interior

The polycarbonate cover keeps most natural rainfall away from the beds, so watering must be provided deliberately. Drip lines or targeted watering are practical options because they deliver water to the root zone while keeping foliage drier.

Watering frequency depends greatly on soil type, temperature, crop size and density, and the season. Heavy soil retains water differently from sandy ground or a raised bed. Rather than following a rigid weekly schedule, check the actual soil moisture.

Collected rainwater can be used for watering beds. Position containers and route lines so paths and access to the front door remain clear.

Start with 4 m and match extensions to your real growing-space needs

In many home gardens, the standard length already provides room for several crops. Extra sections are useful when more cultivated bed space will be needed over the long term, allowing the high tunnel to grow with the vegetable plot or a property developed in stages.

Before the first assembly, it is still worth considering the possible final length. Paths, irrigation lines, compost space and nearby beds are easier to arrange when a future extension direction remains free.

A longer version may suit a smaller food garden when several crop groups need separate areas. Add that space only if there is enough time and capacity to plant, water and maintain it properly.

Check the frame and fasteners before winter and after severe weather

Snow can vary substantially in weight with moisture, wind movement and temperature, and may collect unevenly on the roof.

Inspect the tunnel externally after heavy snowfalls and stormy periods. Unusual distortion, loose fasteners or one-sided snow accumulation should be checked and addressed promptly. Remove snow only in a way that will not damage the polycarbonate panels or steel frame. Do not use sharp tools or walk on the cover. Avoid creating a heavily uneven load while clearing it.

Before the cold season, systematically inspect M5 screws, D40 plastic washers, side windows, the door and ground anchoring. Clean transitions between frame and panels, remove plant debris and make sure all moving parts close. Loose pots, equipment or supports must not be positioned inside where they can strike the panels. Work from the entrance to the tunnel end so less visible areas are included.

Sequence new plantings and use the cleared tunnel for inspection

Decide the order of planned crops early. A bed can then be prepared for its next planting after harvest without disrupting neighbouring crops or the working path.

Clear harvested sections completely before the next crop moves in. Remove diseased plant material from the tunnel and prepare soil for the intended follow-on crop. Check supports and irrigation components in the relevant bed area at the same time.

After the final clear-out, remove ties, empty pots and labels, and clean work areas. Check irrigation for blockages or damage. Then use the open interior for a thorough visual inspection of the frame, fasteners and panels, which are easier to reach without dense foliage.

Generous protected growing space for community and home gardens

The high tunnel suits larger home gardens and sites where efficient use of growing space matters more than the ornamental appearance of a traditional greenhouse. Its practical shape puts sheltered growing area first.

Before installing the tunnel in a community garden or another shared growing site, confirm the site's rules for size, placement and setbacks. For the property itself, ask the relevant provincial or territorial authority and municipality which zoning, permit and adopted-code requirements apply. National model codes do not take effect everywhere simply because they are published. Have a qualified local designer assess the foundations and the site's snow and wind conditions.

Its consistent width supports a clear, repeatable arrangement of paths, beds and watering, including after a later extension.

FAQ – Bloomcabin High Tunnel Greenhouse