Roundups / Greenhouses under £400

Grow-your-own · UK product comparison

Best greenhouses under £400 compared in 2026

If you want a greenhouse for under £400, the choice mostly comes down to how much ground you can give it and what you want the frame made of. This roundup covers two small shelved models for patios and narrow spots, plus three walk-in aluminium greenhouses from Palram-Canopia. The 6x4 models give you standing height of 208 cm, while the 6x8 stretches the floor space to 247 cm in length. Timber frames suit a traditional look, whereas the aluminium models weigh 26.5 to 39.1 kg. All five are self-assembly, so clear and level your site before delivery.

P&P

Plot & Pot editors
We compare published product details, sizes and materials. These are desk-researched product roundups, not hands-on tests.

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Our stand-out pick

Palram-Canopia Mythos 6x4 Greenhouse, Silver

The Palram-Canopia Mythos 6x4 Silver offers a useful balance of space, weight and price. At £289 you get a walk-in 185 × 126 × 208 cm greenhouse with an aluminium frame, twin-wall polycarbonate glazing, a hinged door and an opening window. At 26.5 kg it is the lightest model here, and its 5-year defects and workmanship warranty is longer than the 12-month parts cover on the Rowlinson.

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At a glance

Our picks compared

Prices are dated snapshots and can change. Product dimensions are shown as width × depth × height.

Product	Brand	Price snapshot	Retailer	Dimensions	Weight	Frame	Glazing	Shelves	Lids	Assembly	Warranty	Lid	Floor	Door	Ventilation	Extras
Rowlinson Hardwood Mini Greenhouse	Rowlinson	£229.00	One Garden	120 × 63 × 144 cm	30 kg	FSC hardwood	Twin-wall polycarbonate	2	2 lifting lids with adjustable stays	Self-assembly, 1 to 2 hours	12-month parts	—	—	—	—	—
Zest Compact Botanical Greenhouse	Zest	£329.00	One Garden	85 × 40 × 123 cm	40 kg	Pressure-treated softwood	Perspex	2 large removable shelves	—	Self-assembly	10-year anti-rot	Opening lid with stay	Not supplied	—	—	—
Palram-Canopia Mythos 6x4 Greenhouse, Silver	Palram-Canopia	£289.00	One Garden	185 × 126 × 208 cm	26.5 kg	Rust-resistant aluminium	Twin-wall polycarbonate	—	—	Self-assembly, 2 people, 4 to 6 hours	5-year defects and workmanship	—	—	Hinged single door	1 opening window and 1 roof vent	Gutters and galvanised steel base
Palram-Canopia Hybrid 6x4 Greenhouse, Green	Palram-Canopia	£354.00	One Garden	185 × 126 × 208 cm	27.4 kg	Powder-coated aluminium	Polycarbonate roof and wall panels	—	—	Self-assembly, 2 people, 4 to 6 hours	5-year defects and workmanship	—	—	Hinged door	1 opening window	—
Palram-Canopia Mythos 6x8 Greenhouse, Silver	Palram-Canopia	£319.00	One Garden	185 × 247 × 208 cm	39.1 kg	Rust-resistant aluminium	Twin-wall polycarbonate	—	—	Self-assembly, 2 people, 4 to 6 hours	5-year defects and workmanship	—	—	Hinged door	1 opening window	—

The details

Five greenhouses under £400, compared

01 · Best for patios and balconies

Rowlinson Hardwood Mini Greenhouse

A compact hardwood mini with built-in shelves and two adjustable lids for limited floor space.

The Rowlinson Hardwood Mini is the smallest and lowest priced model here at £229, measuring 120 × 63 × 144 cm. The hardwood frame is paired with twin-wall polycarbonate glazing, giving a warmer, more natural look than bare metal. Two shelves give you room to arrange seed trays and pots, and two lifting lids with adjustable stays let you vary how far the greenhouse opens. At 30 kg it is manageable to position on a patio or against a wall. It is self-assembly and has a 12-month parts warranty, so it suits gardeners wanting a simple growing space for seedlings and young plants.

Price snapshot: £229.00 at One Garden, recorded 2026-11-02. Check the retailer page for the current price.

Key specifications

Dimensions: 120 × 63 × 144 cm
Weight: 30 kg
Frame: FSC hardwood
Glazing: Twin-wall polycarbonate
Shelves: 2
Lids: 2 lifting lids with adjustable stays
Assembly: Self-assembly, 1 to 2 hours
Warranty: 12-month parts

What stands out

Two shelves and two adjustable lifting lids in a small footprint
Hardwood frame with twin-wall polycarbonate glazing

Things to consider

The 12-month parts warranty is the shortest in this group

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02 · Best for narrow spaces

Zest Compact Botanical Greenhouse

A very slim softwood greenhouse with removable shelves for places where a walk-in model will not fit.

The Zest Compact Botanical is the slimmest model here at 85 × 40 × 123 cm, so it can fit against a wall or along a narrow patio edge. It combines a pressure-treated softwood frame with Perspex glazing, and two large removable shelves let you rearrange the inside for different pots and trays. The opening lid has a stay to hold it up. A 10-year anti-rot warranty covers the timber. It is self-assembly and weighs 40 kg, which is heavier than the 6x4 aluminium models, so plan the lift when positioning it.

Price snapshot: £329.00 at One Garden, recorded 2026-11-02. Check the retailer page for the current price.

Key specifications

Dimensions: 85 × 40 × 123 cm
Weight: 40 kg
Frame: Pressure-treated softwood
Glazing: Perspex
Shelves: 2 large removable shelves
Lid: Opening lid with stay
Floor: Not supplied
Assembly: Self-assembly
Warranty: 10-year anti-rot

What stands out

Very slim footprint for tight spaces
Two large removable shelves and a 10-year anti-rot warranty

Things to consider

No floor is supplied, and at £329 it costs more than the larger Mythos 6x4

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03 · Best overall

Palram-Canopia Mythos 6x4 Greenhouse, Silver

A lightweight walk-in greenhouse that balances standing room, price and warranty.

The Palram-Canopia Mythos 6x4 Silver is a full-height greenhouse at £289, measuring 185 × 126 × 208 cm. The aluminium frame and twin-wall polycarbonate glazing keep the weight down to 26.5 kg, the lightest in this roundup. A hinged single door gives access, and one opening window provides ventilation. It is self-assembly and comes with a 5-year defects and workmanship warranty. It suits gardeners who want room to stand and grow taller plants without the upkeep that comes with a timber frame, and who have space for a standard 6x4 footprint.

Price snapshot: £289.00 at One Garden, recorded 2026-11-02. Check the retailer page for the current price.

Key specifications

Dimensions: 185 × 126 × 208 cm
Weight: 26.5 kg
Frame: Rust-resistant aluminium
Glazing: Twin-wall polycarbonate
Door: Hinged single door
Ventilation: 1 opening window and 1 roof vent
Extras: Gutters and galvanised steel base
Assembly: Self-assembly, 2 people, 4 to 6 hours
Warranty: 5-year defects and workmanship

What stands out

Lightest walk-in model here, at 26.5 kg
208 cm standing height at £289

Things to consider

Only one opening window is listed

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04 · Best for a coloured finish

Palram-Canopia Hybrid 6x4 Greenhouse, Green

The same 6x4 footprint as the Mythos, with a green powder-coated frame for a different look.

The Palram-Canopia Hybrid 6x4 Green shares its 185 × 126 × 208 cm footprint with the Mythos 6x4, so the decision comes down to finish and glazing. It has a powder-coated aluminium frame with polycarbonate roof and wall panels, and the green colour may sit more comfortably among plants than bare silver. At 27.4 kg it is still light for a walk-in greenhouse. You get a hinged door and one opening window, with the same 5-year defects and workmanship warranty. At £354 it suits gardeners who value the coloured finish enough to pay for it.

Price snapshot: £354.00 at One Garden, recorded 2026-11-02. Check the retailer page for the current price.

Key specifications

Dimensions: 185 × 126 × 208 cm
Weight: 27.4 kg
Frame: Powder-coated aluminium
Glazing: Polycarbonate roof and wall panels
Door: Hinged door
Ventilation: 1 opening window
Assembly: Self-assembly, 2 people, 4 to 6 hours
Warranty: 5-year defects and workmanship

What stands out

Powder-coated green aluminium frame
Walk-in 208 cm height at 27.4 kg

Things to consider

It costs £65 more than the Mythos 6x4 of the same size

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05 · Best for more growing space

Palram-Canopia Mythos 6x8 Greenhouse, Silver

A longer walk-in greenhouse with extra floor length for gardeners with room to spare.

The Palram-Canopia Mythos 6x8 Silver measures 185 × 247 × 208 cm, giving far more floor length than the 6x4 models while keeping the same standing height. At £319 it costs £30 more than the Mythos 6x4 and offers a longer growing area. It uses an aluminium frame and twin-wall polycarbonate glazing, with a hinged door and one opening window. It is self-assembly and carries a 5-year defects and workmanship warranty. At 39.1 kg it is the heaviest aluminium model here, so it suits gardeners with a larger plot and a helper for assembly.

Price snapshot: £319.00 at One Garden, recorded 2026-11-02. Check the retailer page for the current price.

Key specifications

Dimensions: 185 × 247 × 208 cm
Weight: 39.1 kg
Frame: Rust-resistant aluminium
Glazing: Twin-wall polycarbonate
Door: Hinged door
Ventilation: 1 opening window
Assembly: Self-assembly, 2 people, 4 to 6 hours
Warranty: 5-year defects and workmanship

What stands out

247 cm length gives more floor space than the 6x4 models
Same aluminium frame, polycarbonate glazing and 5-year warranty as the 6x4

Things to consider

It needs a longer plot, and only one opening window is listed

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