Robust high tunnel greenhouse with ample protected growing space for vegetables, young plants and a longer gardening season

Our Bloomcabin polycarbonate high tunnel greenhouse is designed for gardeners who need a generous, permanently protected growing area for vegetables, young plants and heat-loving crops. The three-metre-wide tunnel shape provides a practical footprint for arranging beds, a working path and irrigation clearly. Unlike a flexible film cover, the six-millimetre polycarbonate panels form a fixed covering on the galvanised steel structure.

The basic length is 4 metres and can be adapted to the required growing space with suitable extension sections. The galvanised steel frame is anchored in the ground through its arches. Together with the permanently fitted polycarbonate cover it creates a stable, protected growing area. Discover our greenhouses and conservatories as well as our guides and planning advice.

More protection than a simple film tunnel – and considerably more growing space than many compact garden greenhouses

This model suits anyone intending to use the space regularly for growing vegetables and plants. It provides room for permanent beds and working paths, while its selectable length can still be tailored to the plot and the actual area required.

Key details of the Bloomcabin high tunnel greenhouse

Width: 3.00 m.

Height: 2.10 m.

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

Frame: Galvanised 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 approx. 35 cm into the ground.

Cover: 6 mm polycarbonate with UV protection.

Access: One door at the front.

Ventilation: Two side windows to regulate temperature and air exchange.

Guarantee: 12 years, subject to the applicable guarantee terms.

A front door and two side windows make access and internal climate control easier

The internal height makes upright work easier and provides space for tall crops such as tomatoes or cucumbers. The front door is the main entrance. Keep the area immediately behind it clear, so watering cans, harvest containers and garden tools can be carried in and out without damaging plants.

Both side windows must remain freely accessible inside and out. Position plants, supports and stored items so the windows can be operated fully. When planning beds, also check that the windows will remain reachable when crops are mature.

Open and close the door and windows regularly to check they work properly. Remove soil and plant debris from moving areas. If a component sticks, investigate the cause first instead of forcing it.

Arrange crops for short routes and easy access

When dividing the interior, consider not only plant type but also growth height, inspection needs and harvesting frequency. This helps make sensible use of the available space and access to every crop.

Plan the location, ground and future use before installation

Measure the footprint for the chosen tunnel length and prepare as level an area as possible. Sufficient working room is needed around the structure to position arches and polycarbonate panels safely. Also plan surface-water drainage: rainfall from the fixed cover must not collect at the structure’s edge or in front of the door.

As the arches extend about 35 cm into the ground, establish the route of underground electricity, water and drainage services before work begins. Do not wait until assembly to remove large stones or other obstacles. On uneven ground, prepare the area so all arches stand on one line and can reach the specified installation depth.

Plan how components will travel from the delivery point to the prepared site. Access must stay clear during assembly; soil, compost and garden tools must not obstruct the work area. Remember that both long sides must remain accessible from outside after installation for inspections and care.

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

When is a high tunnel the better choice than a classic aluminium greenhouse?

A classic aluminium greenhouse offers a straight-lined appearance, different design possibilities and can become a visible feature in the garden.

With a high tunnel, the priority is a large continuous growing area, robust construction and the option of modular extension.

Choose the high tunnel when you need as much protected space as possible for productive growing. A classic greenhouse is a better fit where a rectilinear form and visual integration into the garden matter more.

Adapt use and care to your site and local weather conditions

Gardening conditions vary considerably between locations and plots in Malta. Exposed gardens may be windier, while sheltered sites can retain more heat and humidity. Use the high tunnel according to your garden’s microclimate rather than a fixed calendar. Monitor conditions locally and ventilate early during warm, bright weather.

For early crops, the protected space can offer a useful advantage in cooler periods. Later in the season, heat-loving plants benefit when rain and wind affect leaves and fruit less directly. Harvesting can continue into milder autumn conditions as long as light, temperature and plant health remain suitable.

During the first season, note unusual temperature patterns, humid periods and areas of weaker plant growth. These records help tailor crop placement and care routines more precisely to the site the following year.

Choose a sunny position and leave sufficient room for air exchange

A sunny position is particularly useful in cooler growing periods. Observe when buildings, walls, hedges and trees cast shade across the intended area. At the same time, leave enough distance from obstacles for both side windows to ventilate effectively.

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

Also consider future maintenance when selecting the site. The front door must be easy to reach, and there should be enough room along both sides to inspect windows, polycarbonate panels and fixings from outside.

Arrange tomatoes, cucumbers, peppers and early salads sensibly across 3 m width

The fixed 3 m width works well for two side bed rows with a central working path, or three narrower growing zones. Place tall plants such as tomatoes and cucumbers so they do not unnecessarily shade lower crops. If using strings or supports, plan their fixing points before planting.

In cooler periods, salads, kohlrabi, radishes, herbs and young plants can use the protected space before heat-loving summer crops take over. After the main season, part of the tunnel can again be used for sturdy leafy vegetables or later herbs.

Mark occupied bed sections and record which crops were grown there. This makes planning the next planting easier without having to reorganise paths or ventilation areas.

Act early on hot days before heat and high humidity build up

In Malta, a closed tunnel can heat up very quickly on sunny days. Open the side windows before plants show signs of heat stress. Early ventilation softens temperature peaks and moves humid air out of dense planting.

Especially with tomatoes, it is useful to keep foliage as dry as possible and avoid unnecessarily encouraging condensation. Ventilate on mild days too, when outdoor air allows good exchange. After watering, excess moisture should be able to leave the crop area.

During extended hot spells, adjusted watering times and, where needed, temporary shading can help. The right measures depend on location, orientation and the crop canopy.

Bring water directly to roots instead of dampening the whole interior

The polycarbonate cover keeps natural rainfall largely away from the beds. Water supply therefore needs to be managed deliberately. Drip hoses or spot watering are particularly practical because they bring water directly to the root zone and help keep leaves drier.

Watering frequency depends greatly on soil type, temperature, crop size and density, and the time of year. Heavy soil stores water differently from sandy ground or a raised bed. Do not water by a rigid weekly schedule; check the actual soil moisture instead.

Collected rainwater can be used to irrigate beds. Place containers and run lines so that paths and access to the front door remain clear.

Start with 4 m and match extensions to the space genuinely needed

The basic length already provides space for several crops in many private gardens. Additional sections make sense where more cultivable bed area is permanently needed. In this way, the high tunnel can grow with vegetable production or the gradual development of the plot.

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

For smaller self-sufficiency gardens, a longer version can be attractive when several crop groups are to be separated. Choose the extra area only if it can genuinely be cared for, watered and planted.

Check frame and fixings before winter and after severe weather

Wind-driven debris, heavy rain and changing temperatures can place uneven demands on the structure and cover.

Inspect the tunnel externally after severe weather and strong winds. Unusual deformation, loosened fixings or debris collecting on one side should be checked and addressed promptly. Remove debris only in a way that does not damage polycarbonate panels or the steel frame. Do not use sharp tools or walk on the cover. Avoid creating a heavily one-sided load while clearing.

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

Replant beds methodically and use the cleared tunnel for inspection

Set the sequence of planned crops early. A bed can then be prepared specifically for the 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 parts from the tunnel and prepare the soil for the intended follow-on crop. At the same time, check supports and irrigation components in the relevant bed area.

After the final clearance, remove tying materials, empty pots and labels, and clean working areas. Check irrigation for blockages or damage. Then use the open interior for a thorough visual inspection of the frame, fixings and panels, as these areas are easier to access without dense foliage.

Ample protected growing area for allotment and home gardens

The high tunnel suits larger home gardens as well as plots where efficient use of available growing space matters more than the decorative appearance of a classic greenhouse. Its functional form puts protected plant space first.

Before assembly, have a perit check the Planning Authority classification for your proposal, including footprint, height, enclosure, land designation and any existing permit conditions. A domestic garden location or removable kit does not itself establish permission.

The consistent width makes paths, beds and irrigation easy to divide clearly and repeatably, even when extending later.

FAQ – Bloomcabin high tunnel greenhouse