Lean-To Greenhouse Guide: Buying, Positioning and What to Grow
A lean-to greenhouse sits against an existing wall and uses the wall's stored heat to stay warmer overnight. Lean-to models start from £219 for a compact Palram Canopia up to £8,350 for a Janssens Arcadia cedar frame. South or south-west facing walls give the best results. A standard 4x6ft lean-to needs just 1.3m of garden depth, so they suit small gardens, courtyards and side passages where a freestanding greenhouse won't fit.
Key Takeaways
- A south-facing brick wall gives the best growing conditions. The thermal mass stores heat during the day and releases it at night.
- Lean-to greenhouses are 3-5°C warmer overnight than freestanding models of the same size.
- Check your wall is plumb and in good condition before ordering. Uneven walls need a timber framework (we have a guide for this).
- Our lean-to range starts at £219 for the Palram Canopia and goes up to £8,350 for the Janssens Arcadia.
Installer's Note
We've fitted lean-to greenhouses against every kind of wall. Smooth brick, rough render, pebbledash, even a converted barn. The single biggest mistake we see is people choosing an east or north-facing wall because it's the most convenient spot. That wall gets almost no direct sun. Move it to the south side and you'll grow twice as much. The other common problem is an uneven wall. We always check the wall with a spirit level first. If it's more than 10mm out of plumb, we build a timber goalpost frame to create a flat mounting surface.
Why choose a lean-to greenhouse?
Lean-to greenhouses have one clear advantage over freestanding models: thermal mass. The wall your greenhouse sits against absorbs heat from the sun during the day. At night, that stored heat radiates back into the greenhouse. A lean-to against a south-facing brick wall runs 3-5°C warmer overnight than a same-size freestanding model. That means lower heating bills in winter and earlier sowing in spring.
The space saving is the other big draw. A 4x6ft lean-to like the Elite Windsor 4x6 needs just 1.3m of garden depth. You can tuck it against a house wall, garage wall or garden wall. Side passages, courtyards and small patios suddenly become growing spaces.
Access is easier too. Your lean-to is right against the house, so running an extension lead for a heater or propagator takes seconds. You'll pop in more often when it's two steps from the back door.
Which wall should a lean-to face?
South-facing is the best option. A south wall receives direct sunlight for most of the day from March to October. South-west is the second best choice. The afternoon sun heats the wall late in the day, which keeps the greenhouse warmer through the evening.
West-facing walls work, but you lose the morning sun. East-facing is worse: morning light only, which doesn't help much with heat storage. Avoid north-facing walls altogether. Almost no direct sun, and your lean-to will stay cold and damp.
The wall material matters too. A solid brick wall stores the most heat. Rendered blockwork is slightly less effective. Timber-clad walls and metal cladding store very little heat. You won't get the thermal mass benefit from those.
Matt's Tip: Test your wall first
Before you order, put your hand on the wall at about 5pm on a sunny afternoon. A good brick wall feels noticeably warm to the touch. That warmth is what keeps your greenhouse going through the night. If the wall feels cold even in sunshine, you won't get much thermal benefit from a lean-to.
What size lean-to greenhouse do I need?
Lean-to greenhouses are measured by depth (projection from the wall) and width (how far along the wall). Most models come in 4ft or 6ft depth. Width ranges from 2ft for a compact mini lean-to up to 12ft for a full-size growing space.
For growing tomatoes and cucumbers, you need at least 4ft depth. Anything shallower and you can't fit grow bags and still walk inside. A 4x6ft lean-to is the sweet spot for most people. It gives you enough room for two rows of grow bags, a small staging bench, and a narrow walkway.
If you're planning to overwinter tender plants like citrus trees or large pelargoniums, go for a 6x8ft model. The extra depth and width gives you floor space for large pots and enough headroom for standard citrus trees. Our greenhouse sizing guide covers this in more detail.
Lean-to vs freestanding greenhouse: which is better?
Neither is better overall. It depends on your garden and what you want to grow. Here's the honest comparison.
| Feature | Lean-to | Freestanding |
|---|---|---|
| Overnight temperature | 3-5°C warmer (thermal mass) | Drops faster after sunset |
| Light levels | Wall blocks light on one side | Light from all directions |
| Space needed | 1.3m depth for a 4ft model | Full footprint plus access all round |
| Planning permission | Usually permitted development | Usually permitted development |
| Price range | £219 - £8,350 | £200 - £12,000+ |
| Best for | Small gardens, overwintering, herbs | Full crop production, large spaces |
| Wall condition | Wall must be plumb and sound | No wall needed |
One thing competitors won't tell you: a lean-to receives less light overall because the wall blocks one side. For crops that need full sun all day (peppers, aubergines), a freestanding greenhouse may perform better. For herbs, overwintering, seedlings and salads, the lean-to's extra warmth more than makes up for it. Read our glass vs polycarbonate guide for more on glazing options.
Our lean-to greenhouse range: what we sell and what we'd pick
We stock lean-to greenhouses from four manufacturers. Here's a quick summary of where each one sits in the range.
At entry level, the Palram Canopia at £219 is a compact 4x2ft polycarbonate lean-to. It works like a cold frame, protecting overwintering pots or hardening off seedlings. You can't walk inside it.
The Access Harlow Mini at £349 is a 2x3ft toughened glass mini lean-to. Again, a sheltered growing space rather than a walk-in greenhouse. Good for herbs against a kitchen wall.
For a proper walk-in lean-to, the Elite Windsor range starts at £429 for the 4x4ft. The 4x8ft toughened glass version costs £799. We fit more Windsor lean-tos than any other brand. The frame is well-made and the door mechanism has got better over the last few years.
The Vitavia IDA range starts at £449 for the 4x8ft model and £684 for the 6x8ft version. Good value for the internal space you get.
At the top end, the Elite Kensington at £799 gives you 6x8ft in aluminium with a wider door opening. And the Janssens Arcadia cedar range runs from £3,150 to £8,350 if you want cedar and proper Victorian looks.
Browse our full selection of lean-to greenhouses to compare sizes and prices.
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Matt's Pick: Best all-round lean-toBest For: First-time lean-to buyers who want a proper walk-in greenhouse Why I Recommend It: I've fitted more of these than any other lean-to. The frame is solid, the door slides well, and 4x6ft fits grow bags plus a small staging bench. It's the size most people end up wishing they'd bought if they start with a 4x4. Price: £479 |
How to prepare for a lean-to installation
The wall is the first thing to check. Run a 2m spirit level vertically against it. If the wall is more than 10mm out of plumb, you'll need a timber framework for a flat surface. We've written a full guide on fixing a lean-to greenhouse on an uneven wall.
Next, check the wall for cracks, crumbling mortar, or damp. The greenhouse frame bolts directly to the wall using frame fixings. The wall must be solid enough to take the weight and wind load of the greenhouse. Repair any loose mortar before installation day.
The base needs to be level and flat. Most lean-to greenhouses sit on a concrete plinth or paving slabs. The base must be square. We measure the diagonals. If both match within 5mm, the base is square. Our concrete base guide and paving slab base guide cover both methods.
Finally, think about what's above the lean-to. Overhanging gutters, satellite dishes and wall lights all need to be moved or the greenhouse positioned to avoid them. We see this on at least a third of our lean-to installations.
Planning permission for a lean-to greenhouse
Most lean-to greenhouses count as permitted development under Class E of the GPDO 2015. You don't need planning permission if the ridge height stays under 2.5m within 2m of a boundary. Every lean-to in our range sits under this limit. The tallest model, the Janssens Arcadia 12ft, has a ridge height of 2.38m.
Attached structures do have one extra rule. The combined ground area of all outbuildings (including your lean-to) must not exceed 50% of the total garden area. Our full planning permission guide covers conservation areas, listed buildings and Scotland.
What to grow in a lean-to greenhouse
That warm back wall is why lean-tos produce better heat-loving crops. Tomatoes grown against the back wall benefit from the radiated heat and ripen faster than in a freestanding greenhouse. Train cordon tomatoes vertically against the wall to maximise floor space.
Herbs are a natural fit, especially if the lean-to is against a kitchen wall. Basil, parsley, coriander and chives all thrive in a lean-to. Place herb pots on staging at waist height for easy picking.
For overwintering, the thermal mass of the wall keeps frost at bay longer than a freestanding greenhouse. Citrus trees, pelargoniums, fuchsias and dahlias all survive through winter in an unheated lean-to against a south-facing brick wall. Our accessories guide covers staging, thermometers and other essentials for setting up your growing space.
Frequently asked questions
Do I need planning permission for a lean-to greenhouse?
Usually no. Most lean-to greenhouses fall under permitted development. The ridge height must stay under 2.5m if the lean-to is within 2m of a boundary. All lean-to models in our range meet this limit. Check our planning permission guide for conservation area and listed building exceptions.
Which wall should a lean-to greenhouse face?
A south or south-west facing wall gives the best results. South walls receive direct sunlight for most of the day between March and October. The brick absorbs this heat and releases it overnight, keeping the greenhouse 3-5°C warmer than the outside temperature. West-facing walls are acceptable. Avoid north-facing walls.
How much does a lean-to greenhouse cost?
Lean-to greenhouses in our range cost from £219 to £8,350. The Palram Canopia polycarbonate mini lean-to starts at £219. Walk-in aluminium lean-tos start from £429 for the Elite Windsor 4x4. Premium cedar-framed Janssens Arcadia models run from £3,150 to £8,350.
Is a lean-to warmer than a freestanding greenhouse?
Yes, a lean-to is typically 3-5°C warmer overnight. The back wall stores heat from the sun during the day and releases it slowly after dark. This thermal mass effect is strongest with a solid brick wall facing south. Rendered blockwork provides a similar benefit. Timber-clad walls store less heat.
Can I attach a lean-to greenhouse to a fence or shed?
No. Lean-to greenhouses must be fixed to a solid masonry wall. A fence cannot support the weight and wind load. Garden sheds are not strong enough either. The wall must be brick, block, stone or concrete. Timber-framed buildings are not suitable for lean-to installation.
