Large Greenhouses

About Our Large Greenhouses

Large greenhouses offer walk-in growing space that transforms how you garden. With models from 10ft to 19ft wide, you'll have room for proper pathways, diverse planting zones, and comfortable year-round growing. Our collection features box section aluminium frames with 3mm or 4mm toughened glass glazing—built to withstand decades of British weather. Choose from 10ft wide Greenhouses, 12ft wide Greenhouses, or 14ft wide Greenhouses depending on your plot size. Every model includes built-in gutters, roof vents, and double doors wide enough for wheelbarrows. We provide free UK delivery and warranties spanning 10 to 25 years—because a large greenhouse is a 20-year investment, not a quick purchase.

Choosing Your Large Greenhouse

Size matters significantly at this scale. A 10ft wide model (typically 10x8ft) gives you 80 square feet—enough for staging on both sides plus a central path. Step up to 12ft wide (often 12x8ft) and you gain 96 square feet, ideal for serious vegetable growers or small commercial use. Our 14ft, 17ft, and 19ft models suit dedicated growers who need zoning for propagation, growing, and overwintering.

Material choice affects your workload. Aluminium frames need zero maintenance and last 25+ years without rot. Wooden Greenhouses offer traditional aesthetics but require treatment every 2-3 years. For glazing, toughened glass provides 90% light transmission and never yellows, while polycarbonate offers better insulation but scratches more easily.

Prices start from £910 for compact 10ft models and reach £18,950 for premium 19ft structures with full toughened glass. Most customers spend £2,500-£5,000 for a well-specified 12ft greenhouse. Browse our Janssens Greenhouses range for Belgian-engineered quality, or explore Bespoke Greenhouses if standard sizes don't fit your plot.

Key Features of Large Greenhouses

• Wide Frames: 10ft, 12ft, 14ft, 17ft, and 19ft widths accommodate serious growing operations
• Safety Glazing: 3mm or 4mm toughened glass that won't crack from hail or impact
• Box Section Construction: Aluminium frames with integrated base plinth for superior strength
• Multiple Finishes: Silver, green, or black powder-coated frames to match your garden
• Proper Ventilation: Roof vents and louvre side vents for temperature control in summer
• Wide Access: Double doors allow wheelbarrow entry and furniture-sized plant movement
• Water Management: Built-in gutters with downpipes channel rainwater to collection butts

Foundation and Siting for Large Structures

You cannot skip the base with a large greenhouse. Structures over 10ft wide need a level, solid foundation—either a concrete slab or paving slabs on compacted hardcore. An uneven base will twist the frame and prevent doors from closing properly. Our How to Prepare a Greenhouse Base guide covers DIY methods and costs.

Position your greenhouse where it receives 6+ hours of direct sun, ideally with the ridge running east-west for even light distribution. Allow 2ft clearance on all sides for maintenance access and gutter cleaning. Consider proximity to water and electricity—running cables and hoses 30 metres gets expensive.

For structures over 30 square metres (roughly 12x10ft), you may need planning permission depending on your location and proximity to boundaries. Check with your local council before ordering. Most large greenhouses qualify as "permitted development" if positioned correctly.

Comparing Materials for Large Greenhouses

Aluminium frames dominate the large greenhouse market for good reason. Box section aluminium provides the strength-to-weight ratio needed for structures holding 100+ glass panes. You'll never paint or treat it, and it won't rot, warp, or attract pests. Expect 25+ years of service. Powder coating in silver, green, or black prevents corrosion in coastal areas.

Timber offers traditional charm but demands commitment. Large wooden greenhouses need treatment with preservative every 2-3 years, and softwood frames can warp if moisture gets trapped. However, wood insulates better than aluminium—potentially saving 15% on winter heating costs. Our Wooden Greenhouses collection includes pressure-treated cedar and redwood options.

For glazing, toughened glass outperforms polycarbonate on large structures. Glass maintains 90% light transmission for decades, doesn't scratch from cleaning, and never yellows. Polycarbonate panels offer better insulation (useful for heated greenhouses) but degrade in UV over 10-15 years. At this scale, the 20-30% premium for toughened glass delivers better long-term value.

Size Selection Guide

10ft Wide Models (10x6ft to 10x12ft)

Perfect for serious hobby growers. You'll fit two runs of staging (2ft deep each) with a comfortable 6ft central path. Typical capacity includes 40-50 tomato plants, 30 pepper plants, or mixed growing with space for a small propagation area. Annual running costs around £150 for heating in a cold winter.

12ft Wide Models (12x8ft to 12x16ft)

This sweet spot suits semi-commercial growers and passionate gardeners. Add three staging runs or create distinct zones—propagation at one end, main growing in the middle, overwintering at the far end. You can grow 80+ tomato plants or maintain a year-round salad supply for a family of six. Heating costs rise to £250-£350 annually.

14ft+ Wide Models

Built for commercial operations, plant nurseries, or collectors with extensive orchid or citrus collections. These structures need Greenhouse Installation Service due to their size—professional fitting takes 2-3 days and ensures warranty compliance.

Heating and Ventilation Considerations

Large greenhouses create microclimates that need active management. In summer, temperatures can hit 40°C without adequate ventilation—you'll need roof vents covering at least 20% of floor area plus louvre vents on opposite walls for cross-flow. Automatic vent openers (from £45 each) save daily trips to open and close.

Winter heating costs depend on your growing goals. Keeping frost-free (2-4°C) costs roughly £12-£18 per square metre per winter using electric heaters. Raising temperatures to 10°C for Mediterranean crops multiplies costs by 3-4x. Bubble insulation on internal glazing cuts heating bills by 30-40% but reduces light levels.

Consider Lean-to Greenhouses if you want to benefit from house wall warmth—these save 25-35% on heating versus freestanding models.

Frequently Asked Questions about Large Greenhouses

• What qualifies as a large greenhouse?

  Any greenhouse 10ft wide or larger counts as "large" in the UK market. Standard greenhouses measure 6ft or 8ft wide, so 10ft+ models offer 50-150% more growing space. Most large greenhouses range from 80 to 200 square feet of floor area.

• Do I need planning permission for a large greenhouse?

  Most large greenhouses qualify as permitted development if they're under 30 square metres (roughly 12x10ft), more than 5 metres from your house, and don't exceed 4 metres in height. Structures over 30 square metres or those in conservation areas typically need permission. Always check with your local planning authority before purchasing.

• How much does a large greenhouse cost?

  Prices start from £910 for basic 10ft wide aluminium models and reach £18,950 for premium 19ft structures with full toughened glass. Most customers spend £2,500-£5,000 for a well-specified 12ft greenhouse including delivery. Greenhouse Installation Service adds £400-£1,200 depending on size and site complexity.

• What's the best base for a large greenhouse?

  Concrete slabs or paving slabs on compacted hardcore provide the only suitable foundation for greenhouses over 10ft wide. The base must be perfectly level (within 10mm across the entire area) and project 4-6 inches beyond the frame on all sides. Budget £300-£800 for materials depending on size. See our How to Prepare a Greenhouse Base guide for full instructions.

• How long does it take to build a large greenhouse?

  DIY assembly of a 10ft greenhouse takes 2-3 full days for two people with moderate building skills. 12ft models need 3-4 days, and 14ft+ structures typically require professional installation. Our installation team completes most large greenhouses in 1-2 days, and installation is included in many of our premium models' prices.

• Can I add staging and shelving to any large greenhouse?

  Yes, and we make this simple. On each greenhouse product page, we list all compatible accessories—from staging and shelving to extra vents and rainwater kits. You'll see only accessories that actually fit your chosen model, backed by our 15+ years of greenhouse expertise. This ensures perfect compatibility before you add items to your basket.

• Which brands make the most reliable large greenhouses?

  Our Janssens Greenhouses consistently rank highest for build quality and longevity in large sizes, with some customers reporting 30+ years of service. Elite and Vitavia offer excellent value in the £2,000-£4,000 range. For traditional aesthetics, Swallow manufactures timber greenhouses in Yorkshire with 12-year rot warranties.

Getting Started with Your Large Greenhouse

Browse our collection above to compare specific models, dimensions, and features. Every greenhouse includes detailed specifications, and our product pages show compatible Greenhouse Accessories—from automatic vent openers to staging systems—so you can build your complete setup in one order.

Download our free Greenhouse Growing Guide for month-by-month advice on maximizing your growing space. If you need help choosing the right size or have questions about site preparation, call our team on 0800 098 8877 or email sales@greenhousestores.co.uk—we've helped over 50,000 customers find their perfect greenhouse since 2012.