You’ve been growing vegetables in raised beds for a couple of seasons and you’ve hit the wall that every UK grower hits: the weather. Tomatoes that need warmth get battered by June rain. Seedlings started indoors stretch for light and keel over when hardened off. Your pepper plants produce three anaemic fruits before October frost finishes them. A greenhouse fixes all of this — and in the UK’s unpredictable climate, it’s the single most impactful upgrade you can make to your growing setup.
In This Article
- Best Overall: Eden Burford Zero Threshold
- Glass vs Polycarbonate vs Plastic
- What Size Greenhouse Do You Need
- Best Greenhouses by Category
- Frame Materials
- Site Preparation and Foundations
- Ventilation and Temperature Control
- Heating Your Greenhouse
- What to Grow in a Greenhouse
- Frequently Asked Questions
Best Overall: Eden Burford Zero Threshold
If you want one recommendation: the Eden Burford 106 (about £600-700 from garden centres and online retailers). It’s a 6×8ft aluminium-framed greenhouse with toughened safety glass, a zero-threshold doorway (no tripping bar — brilliant for wheelbarrows), and a 10-year frame guarantee. Eden is a UK brand with decades of reputation, and the Burford is their best-selling model for good reason.
It’s big enough to grow tomatoes, peppers, aubergines, and cucumbers while still leaving staging space for seed starting. The toughened glass is safer than horticultural glass (doesn’t shatter into dangerous shards) and retains marginally more heat.
Glass vs Polycarbonate vs Plastic
This is the biggest decision and it affects cost, durability, light transmission, and heat retention.
Toughened Glass
- Light transmission: 90%+ — the best available. Plants get maximum light
- Heat retention: good. Glass holds warmth better than single-skin polycarbonate
- Durability: won’t yellow, scratch, or degrade over decades. But can still break if hit hard (cricket balls, storm debris, clumsy manoeuvring of garden equipment)
- Safety: toughened glass crumbles into small cubes rather than jagged shards. Standard horticultural glass breaks into dangerous pieces — avoid this if children or pets use the garden
- Cost: mid-range. More expensive than polycarbonate panels but less than twin-wall polycarbonate
- Best for: permanent installations where light quality matters most
Polycarbonate (Twin-Wall)
- Light transmission: 80-85% — slightly less than glass but perfectly adequate
- Heat retention: excellent. The double-wall structure traps an insulating layer of air, keeping the greenhouse warmer overnight. This matters hugely in the UK where spring nights drop to 2-5°C
- Durability: virtually unbreakable. Won’t shatter, crack, or pose a safety risk. Can yellow after 10-15 years with UV exposure
- Weight: much lighter than glass, making assembly easier
- Cost: similar to toughened glass overall. Cheaper panels but slightly more complex frame systems
- Best for: exposed or windy sites, gardens with children, and growers who want maximum heat retention
Plastic Film (Polytunnels)
- Light transmission: 85-90% when new, degrades to 70-80% over 3-5 years
- Heat retention: poor. Single skin offers minimal insulation
- Durability: the cover needs replacing every 3-5 years. The frame lasts 15-20 years
- Cost: by far the cheapest option. A 10×20ft polytunnel costs about £200-350
- Best for: allotments, large-scale growing, anyone on a budget who doesn’t mind the agricultural look
Which to Choose
For a garden greenhouse that’ll last decades and look attractive: toughened glass. For maximum warmth retention and safety in a family garden: twin-wall polycarbonate. For growing on an allotment or large area where appearance doesn’t matter: polytunnel.
What Size Greenhouse Do You Need
Minimum Useful Size: 6×4ft (1.8×1.2m)
Space for a small staging bench, a few grow bags on the floor, and seed starting trays. Enough for tomatoes, peppers, and herbs. You’ll outgrow it within one season if you get serious — everyone does.
Sweet Spot: 6×8ft (1.8×2.4m)
The most popular size in UK gardens. Room for two rows of grow bags (4-6 tomato plants), a full staging bench, and floor space for pots and propagators. This is what most growers need and the size I’d recommend as a first greenhouse.
Comfortable: 8×10ft (2.4×3m)
Enough to section off an area for seed starting while maintaining a full growing area. Room for a small potting bench inside. You’ll never feel cramped, and there’s space for experimentation — trying new crops, starting strawberries, or overwintering tender plants.
Large: 8×12ft+ (2.4×3.6m+)
For serious growers. Multiple growing zones, space for a heated propagator, room for citrus trees in pots, and still enough floor space to work comfortably. Check whether your garden has space and whether planning permission is needed (see FAQ).
Best Greenhouses by Category
Best Glass Greenhouse: Eden Burford 106
- Price: about £600-700
- Size: 6×8ft
- Material: toughened safety glass, powder-coated aluminium frame
- Features: zero-threshold door, adjustable roof vents, integral gutters
- Why: the benchmark for domestic glass greenhouses. Build quality is excellent, the instructions are clear, and the zero-threshold door is a quality-of-life feature you’ll appreciate every time you wheel a barrow in
Best Polycarbonate Greenhouse: Palram Harmony
- Price: about £350-450
- Size: 6×8ft
- Material: twin-wall polycarbonate, aluminium frame
- Features: adjustable roof vent, rain gutters, galvanised steel base
- Why: the best balance of heat retention, safety, and price. The twin-wall panels keep overnight temperatures 3-5°C warmer than glass, which matters for early season growing. Assembly is simple — easier than glass greenhouses because the panels are lighter
Best Budget: Keter Factor 6×6
- Price: about £250-300
- Size: 6×6ft
- Material: polycarbonate panels, resin frame
- Features: lockable door, skylight window, maintenance-free frame
- Why: not a traditional greenhouse — more of a garden building with translucent walls — but it works for growing at a fraction of the price. No painting, no rotting, and it’s quick to assemble
Best Polytunnel: Northern Polytunnels
- Price: about £200-350 (cover + frame)
- Size: 10×16ft (standard domestic)
- Material: 720-gauge polythene, galvanised steel hoops
- Features: timber baseboards, anti-hot-spot tape, crop bars for hanging plants
- Why: Northern Polytunnels is a UK manufacturer (based in Lancashire) with excellent customer service. Their domestic range is designed for UK gardens and allotments. The cover film carries a 5-year UV guarantee, and replacement covers are available when it degrades
Best Mini Greenhouse: Gardman 4-Tier
- Price: about £30-40
- Size: 160cm × 70cm × 50cm
- Material: PVC cover, powder-coated steel frame
- Features: roll-up cover for access, 4 shelves
- Why: not a real greenhouse — it’s a shelving unit with a plastic cover. But for hardening off seedlings, protecting tender plants overnight, and starting seeds in spring, it’s excellent value. Fits on a patio, balcony, or against a sunny wall. Replace the cover every 2-3 years when the PVC degrades
Frame Materials
Aluminium
The standard for modern greenhouses. Lightweight, rust-proof, low maintenance, and strong. Powder-coated finishes (green, black, or anthracite) look better than raw aluminium and resist scratching.
Wood (Cedar or Pressure-Treated Softwood)
Beautiful and traditional. Cedar weathers to a silver-grey and is naturally rot-resistant. Softwood needs treating every 2-3 years. Wooden greenhouses cost more, require more maintenance, and have thicker glazing bars (slightly less light), but they look stunning in a cottage garden. Brands like Gabriel Ash and Alton make premium wooden greenhouses starting from about £2,000.
Steel (Polytunnels)
Galvanised steel hoops are the standard polytunnel frame. Strong, cheap, and lasts 15-20 years. Will rust eventually at ground-contact points. Some manufacturers offer aluminium connectors to reduce corrosion.
Site Preparation and Foundations
Choosing the Location
- South-facing — maximum sun exposure through the day
- Level ground — essential for the frame to sit square and doors to open properly
- Away from overhanging trees — falling branches, bird droppings, and shade are all problems
- Near a water source — you’ll water the greenhouse daily in summer. Dragging a hose 50m gets old fast
- Sheltered from prevailing wind — a fence or hedge on the windward side reduces heat loss and the risk of storm damage
Foundation Options
- Concrete strip foundation — the best option for glass greenhouses. A 15cm wide, 10cm deep concrete strip around the perimeter provides a solid, level base. Cost: about £50-80 in materials for a 6×8ft greenhouse
- Paving slabs — cheaper and easier. Lay slabs flat under the frame base rail. Works well for smaller greenhouses
- Compacted gravel/aggregate — acceptable for polytunnels and plastic greenhouses. Not recommended for glass (uneven settling can crack panels)
- Manufacturer’s steel base — most greenhouse brands sell a steel perimeter base (about £60-100 extra). This levels the frame and provides fixing points. Good for paved or concrete surfaces
Ventilation and Temperature Control
A greenhouse without ventilation becomes an oven. On a sunny day in April, internal temperatures can exceed 40°C — enough to cook your plants. According to the Royal Horticultural Society, greenhouses need a ventilation area equal to at least 20% of the floor space.
Roof Vents
Every greenhouse needs at least one roof vent. Hot air rises, so roof vents are the most effective way to release it. Automatic vent openers (about £15-25 from B&Q or Amazon UK) use a wax cylinder that expands with heat and opens the vent without you being there. Essential if you’re at work during the day.
Louvre Vents
Side-mounted louvres provide cross-ventilation at plant level. Combined with roof vents, they create airflow that prevents stagnant, humid conditions where fungal diseases thrive.
Shade Netting
In summer, shade netting (50-60% shading) reduces temperature peaks by 5-10°C. Drape it over the outside of the greenhouse (not inside — inside traps heat). Costs about £10-20 for a 2×5m piece.
Heating Your Greenhouse
When You Need Heat
Most UK growers don’t need a heated greenhouse — a well-constructed unheated greenhouse extends the growing season by 4-8 weeks at each end. You need heating only if you’re:
- Overwintering tender plants (citrus, fuchsias, pelargoniums) — maintain 5-7°C minimum
- Starting seeds in January/February — frost protection only
- Growing tropical plants — maintain 15°C+
Heating Options
- Electric fan heater with thermostat — about £30-50. The most practical for domestic greenhouses. Set to 5°C overnight and it runs only when needed. Requires a weatherproof outdoor power supply
- Paraffin heater — about £25-40. No electricity needed. Adds CO2 (which plants love) and moisture. But needs manual lighting and refuelling, and produces fumes
- Bubble wrap insulation — not a heater, but tacking bubble wrap (large bubbles, horticultural grade) to the inside of the glass reduces heat loss by 30-50%. Costs about £15-20 and is the cheapest way to keep a greenhouse frost-free
For fleece and cloches, these provide additional localised protection for individual plants inside an unheated greenhouse.
What to Grow in a Greenhouse
A UK greenhouse opens up crops that struggle outdoors:
- Tomatoes — the number one greenhouse crop. Protected from blight, they ripen reliably from July to October
- Peppers and chillies — need sustained warmth that UK summers rarely provide outdoors
- Cucumbers — thrive in humid greenhouse conditions
- Aubergines — borderline outdoors in southern England, reliable under glass
- Melons — possible in a good summer with a heated propagator start
- Grapes — trained along the roof, they produce well in warm years
- Herbs — basil, coriander, and other tender herbs extend their season by months
The allotment planting guide covers what to start in the greenhouse and when to move plants outside.
Frequently Asked Questions
Do I need planning permission for a greenhouse? In most cases, no. Greenhouses fall under permitted development rights if they’re single storey, don’t cover more than 50% of the garden, are behind the front wall of the house, and don’t exceed 2.5m high within 2m of a boundary. If your property is listed or in a conservation area, check with your local planning authority first.
Is glass or polycarbonate better for a greenhouse? Glass offers the best light transmission (90%+) and lasts indefinitely. Polycarbonate retains heat better (twin-wall), is virtually unbreakable, and is safer around children. For most UK gardeners, either works well — choose glass for maximum light or polycarbonate for maximum warmth and safety.
How much does a greenhouse cost? A mini greenhouse starts at about £30. A decent 6×8ft polycarbonate greenhouse costs £350-500. A quality glass greenhouse in the same size runs £500-800. Premium wooden greenhouses start at £2,000+. Factor in £50-100 for base preparation and £30-50 for auto vent openers.
What size greenhouse should I get? 6×8ft for most home growers — it fits 4-6 tomato plants plus a staging bench. If your garden allows and budget permits, go bigger than you think you need. Nobody has ever complained that their greenhouse is too large.
Can a greenhouse be used all year round in the UK? Yes. From January (seed starting with heat) through spring (growing on seedlings), summer (tomatoes, peppers, cucumbers), autumn (late harvests and overwintering), and winter (protecting tender plants). An unheated greenhouse extends the growing season by 4-8 weeks at each end.