A lean-to greenhouse is a greenhouse with only three glass or polycarbonate walls. Its fourth side leans against your house, garage or a garden wall. That shared wall saves space, holds warmth and puts water and power close by.
✅ Quick answer
- A lean-to is like half of a regular greenhouse, split down the roof ridge and attached to a building.
- It works best on a south-facing wall. East or southeast is the next best choice.
- The shared wall means less glazing to lose heat. In our example below, it needs about one third less heat than if that wall were glass.
- Most lean-tos are narrow, about 5 to 12 feet deep, so they fit side yards, patios and small lots.
- The trade-offs: light from one side only, more care with venting, and a careful seal where it meets your house.
Ready to shop? See our lean-to greenhouse kits →
We are a small, woman-owned greenhouse business in Georgia. Lean-tos are one of the styles our customers ask about most, especially homeowners with small yards. We answer those questions personally, so this guide shares what we tell them on the phone.
What is a lean-to greenhouse?
A lean-to greenhouse is a half greenhouse. Picture a regular gable greenhouse, cut in two along the peak of the roof. One half is attached to a building, and the building becomes the back wall.
Clemson University's Home & Garden Information Center describes it the same way. It also notes that a lean-to is useful where space is limited to a width of about 7 to 12 feet. Some people call it a wall greenhouse or an attached greenhouse.
Lean-to, attached or freestanding: what's the difference?
There are three common ways to place a backyard greenhouse. Here is how they compare.
| Style | How it sits | Light | Best for |
|---|---|---|---|
| Lean-to | Long side against a wall | Mostly from one side and the roof | Small yards, patios, side yards |
| Attached even-span | One gable end against a building | From three sides and the roof | More room, easy access from the house |
| Freestanding | On its own, away from buildings | From all sides | Any size, the most sun and airflow |
Based on the greenhouse types described in Clemson HGIC's hobby greenhouse fact sheet.
What are the benefits of a lean-to greenhouse?
A lean-to gives you a real greenhouse in a spot that might otherwise go unused. These are the benefits our customers mention most:
- It saves space. It hugs a wall, so it fits narrow lots, side yards and patios where a freestanding house would not.
- It holds warmth. The house wall does not lose heat like glass does. A masonry wall can also soak up sun by day and give it back at night.
- Water and power are close. An outdoor faucet and outlet are often already on that wall. That saves trenching across the yard.
- It is easy to reach. You can step out of the kitchen or back door to pick herbs, even in bad weather.
- It adds beauty. A glass lean-to can look like a small conservatory and feel like part of the home.
Clemson calls the lean-to the least expensive greenhouse structure. That makes sense, since one whole wall is already built. A premium glass lean-to is still a real investment, though, as you will see below.
What are the disadvantages of a lean-to greenhouse?
A lean-to is not the right fit for every home. Clemson lists limits on space, sunlight, ventilation and temperature control. Here is what that means in your yard:
- Light from one side. Plants lean toward the glass. Turn pots now and then, and keep tall plants at the back.
- It can overheat. A sunny wall plus glass gets hot fast. Roof vents, side windows and shade matter a lot.
- Limited size. The depth is set by the kit and by your wall. You cannot easily make it wider later.
- The house connection needs care. You must seal the joint so rain does not run between the greenhouse and your siding.
- Rules may apply. A structure attached to your house may need a permit. Check with your local building office and HOA first.
⚠️ Watch your roofline: rain and snow sliding off your house roof can land on the greenhouse roof. Place the lean-to under a gutter, not under a roof valley. Ask a contractor if you are not sure.
Which direction should a lean-to greenhouse face?
For most gardeners, a south-facing wall is best. It gets the most sun through the winter, when you need it most. British greenhouse maker Hartley Botanic gives the same advice for lean-tos.
If you do not have a south wall, here is how the other sides compare, based on Clemson's siting advice:
- South or southeast: first choice. Strong winter sun and good warmth.
- East: very good. Clemson notes the east side gets the most sun from November to February. Morning sun is also gentler in summer.
- Southwest or west: workable. Expect hot summer afternoons, so plan for shade and venting.
- North: least sunny. It can still suit shade plants, ferns or a cool space to overwinter plants.
💡 Our tip: stand at your wall at noon in December, or check a sun-path app. Look for trees, fences or a neighbor's house that will shade the glass. Evergreens are the biggest problem, because they block winter sun.
How much heat does a lean-to greenhouse save?
Heat escapes through glazing. A lean-to has one less glazed wall, so it has less surface losing heat. You can estimate the heat you need with the same formula greenhouse engineers use.
📐 The greenhouse heat formula
BTU per hour = Glazed area × U-value × Temperature gap
Glazed area = only the walls and roof that are glass or polycarbonate (not the house wall) · U-value: about 1.25 for single-pane glass · Temperature gap = inside °F minus outside °F
🧮 Worked example: an Arcadia 5x13 lean-to on a 20°F night
- Glazed area (front wall, two end walls and roof): about 238 sq ft, our estimate from the listed size
- U-value for single-pane 4mm glass: 1.25
- Keep it 45°F inside when it is 20°F outside: gap of 25°F
238 × 1.25 × 25 = about 7,400 BTU per hour. Divide by 3.412 = about 2,200 watts. Add 20% for safety = about 2,600 watts.
Now imagine that back wall were glass too. It would add about 115 sq ft of glazing and about 3,600 BTU per hour. So the house wall cuts the heat needed by roughly one third.
These are estimates for comparison, not a quote. Size your heater for your coldest night, not your average one. Our guide to the cost to heat a greenhouse in winter walks through monthly costs and heater sizes.
Lean-to vs. freestanding greenhouse: which should you choose?
Both styles grow great plants. The right choice depends on your yard, your wall and how much you want to grow.
| Question | Lean-to | Freestanding |
|---|---|---|
| Space needed | Narrow strip along a wall | Open yard with room on all sides |
| Sunlight | One side plus roof | All sides |
| Heating | Less glazing to lose heat | More glazing, but more sun too |
| Water and power | Often already on the wall | Usually needs a trench |
| Permits | More likely, since it attaches to the house | Often simpler, but check locally |
Our customers with a sunny south wall and a small yard usually love a lean-to. If your only wall faces north, or you want to grow a lot, a freestanding house is often the better buy.
What can you grow in a lean-to greenhouse?
Almost anything you would grow in a small greenhouse. Because it is narrow, think in layers: benches along the glass, shelves on the house wall, and hanging baskets above.
- Seedlings: start vegetables and flowers weeks early on a sunny bench.
- Herbs and salad greens: easy to reach from the kitchen all winter.
- Tomatoes and peppers: grow well against a warm wall in spring and summer.
- Citrus and tender plants: a lean-to is a classic place to overwinter potted lemons and geraniums.
How do you attach a lean-to greenhouse to a house?
Every house and kit is different, so always follow the kit's manual. In general, the steps look like this:
- Check the rules. Call your building department and HOA before you order.
- Check the wall. It must be solid, square and plumb. Siding, brick and stucco each need different fasteners.
- Build a level foundation. Most kits need a level, square base along the wall. Our practical guide to a greenhouse foundation covers the options.
- Fasten it to the wall. Use hardware suited to your wall type. Some kits, including the Arcadia, do not include wall hardware.
- Seal the joint. Add flashing and weather stripping so water and drafts stay out.
- Plan vents and drainage. Make sure roof runoff goes into the gutter, not against your foundation.
🛠️ About converting a freestanding kit: older versions of this article suggested removing one side of a freestanding greenhouse to make a lean-to. We no longer recommend that. It can weaken the frame and may affect the warranty. If you want to try it, ask the manufacturer and a contractor first.
Which lean-to greenhouse kits do we carry?
Exaco Janssens Arcadia and Arcadia Plus
The Janssens Arcadia lean-to greenhouse is made in Belgium. It shares its design with the Royal Victorian line. It uses 4mm tempered safety glass held in rubber seals, with a black aluminum frame and a 15-year warranty.
Each model has two roof windows, one with an automatic opener. Gutters with downspouts are included. The larger Arcadia Plus models add stronger roof framing and longer roof glass.
| Model | Size (exact) | Floor space | Peak height | Door |
|---|---|---|---|---|
| Arcadia 5x13 | 5'2" x 12'7" | 65 sq ft | 9'2" | Single sliding |
| Arcadia 5x15 | 5'2" x 15' | 75 sq ft | 9'2" | Single sliding |
| Arcadia Plus 8x10 | 7'6" x 10'2" | 76 sq ft | 9'6" | Single sliding |
| Arcadia Plus 8x15 | 7'7" x 15' | 120 sq ft | 9'6" | Single sliding |
| Arcadia Plus 10x10 | 10' x 10'2" | 102 sq ft | 9'10" | Double sliding |
| Arcadia Plus 10x15 | 10' x 15' | 150 sq ft | 10'4" | Double hinged |
Specs from our Arcadia product page, October 2026.
Prices ran from about $9,799 for the Arcadia 5x13 to about $18,499 for the Arcadia Plus 10x15 when we wrote this (October 2026). Check the Arcadia product page for today's price.
📋 Good to know before you order: the Arcadia is an advanced build, best for a contractor or a very skilled handyman. Wall hardware and weather stripping are not included. Arcadia Plus deliveries need a flatbed and forklift to unload. Some sizes are special orders from Belgium, with longer lead times.
Want to see it up close? Read our full look at the Arcadia lean-to greenhouse. You can also browse every model in our lean-to greenhouse collection.
What about Solexx lean-to greenhouses?
Older versions of this post showed a Solexx lean-to. Solexx greenhouses are no longer made, so we no longer recommend them. If you liked Solexx for its sturdy, insulating panels, look at the Riverstone MONT or the Hoklartherm Riga instead. Both use 8mm twin-wall polycarbonate.
No good wall? Consider a compact freestanding house
If your best wall faces north or is in the shade, a small freestanding greenhouse may serve you better. The Hoklartherm Riga 2s and the Riverstone MONT 8x8 both fit small yards and can sit where the sun is best.
📌 About prices: manufacturers update their prices during the year, and we often run sales and promotions. The price on the product page is always the current one. Prices in this article are a guide from when we wrote it (October 2026), not a quote or guarantee. Found a lower price for the same model at an authorized retailer? We offer a Price Match Guarantee - please check the rules first. Call us and we will confirm today's price and any current deals.
Is a lean-to greenhouse right for you?
A lean-to is a great fit if most of these are true:
- You have a sunny wall facing south, southeast or east.
- Your yard is small, or you want the greenhouse close to the kitchen.
- An outdoor faucet and outlet are on or near that wall.
- You are happy to vent and shade it well in summer.
- Your local rules allow a structure attached to the house.
Not sure? Send us a photo of your wall and tell us which way it faces. We will help you choose a size. For installation, see our assembly crews page for independent installers (we are not affiliated with any crew). We also offer free shipping to the continental US.
Frequently asked questions
What is a lean-to greenhouse?
It is a greenhouse attached to a building along its long side. The building forms the back wall, so the greenhouse has three glazed walls and a sloped roof.
Which way should a lean-to greenhouse face?
South is best for most plants. Southeast and east are next. West works with good shade and venting, and north suits shade-loving plants.
Is a lean-to greenhouse warmer than a freestanding one?
It usually needs less heat, because the house wall does not lose heat like glass. In our example, it needed about one third less heat than an all-glass version.
Do I need a permit for a lean-to greenhouse?
Often, yes, since it attaches to your home. Rules vary by town and HOA, so check with your local building office before you order.
Can I attach a lean-to greenhouse to vinyl siding?
Usually, but it takes the right fasteners and careful flashing so water cannot get behind the siding. We suggest a contractor for this step.
How deep is a lean-to greenhouse?
Many are about 5 to 12 feet deep. Our Arcadia models range from 5'2" to 10' deep and up to 15' long.
Thinking about a lean-to?
Tell us which way your wall faces, how long it is and what you want to grow. We will help you pick the right size and let you know about any current sales.
