Gardeners in Victorian-era England realized the benefits of nurturing their tender, exotic plants in glass structures mounted to their property wall to keep the unforgiving weather out and as much heat as possible in.
Today these “sliced-in-half” lean-to greenhouses with slanted roofs are still the rage, but can these designs ever work as well as regular greenhouses?
Do lean-to greenhouses work? Lean-to greenhouses provide an effective and economical method of growing plants and food in a small yard space. Being mounted against a house wall allows them to maintain more consistent temperatures, providing greater plant protection and climate control than greenhouses with four exterior walls.
There can be a certain architectural beauty to a lean-to greenhouse so hey, even if you dip in and out of green-thumb phases, you can always keep them as decorative tool sheds (or a pretty conservatory space!).
In the meantime, let’s look at the whys, whats, and hows of lean-to greenhouses, the pros and cons, plus FAQs about their maintenance, and more…
Lean-To Greenhouses: The Basics
A lean-to greenhouse can provide many benefits and uses for gardeners on all budgets. They come in various designs and there are even kits available for easier installation.
Lean-To Greenhouse Purpose
Lean-to greenhouses are designed to free up room in your garden by making the most of a bare wall or fence on a property with limited space.
They can be set up in any size garden or yard and be as large as a traditional greenhouse, but their space-saving design allows even small-scale gardens to grow plants and vegetables.
Lean-To Greenhouse Designs
They are typically constructed with a simple aluminum frame and toughened glass but smaller decorative ones can be made with acrylic or Victorian-era painted wood frames.
Larger, longer lean-to greenhouse structures can be mounted to a low-level brick wall base so you can hide any tools/supplies for a better aesthetic.
Models range from dwarf or mini greenhouses (usually in the range of 3 ft. x 4 ft. designs and taller two-tier structures) up to wide, walk-in lean-tos (up to 10 ft. x 20 ft.) that can be immediately accessible from inside your house.
Roofs can also be slanted at a steep angle or curved
Lean-To Greenhouse Placement
Your lean-to greenhouse should ideally be supported by a straight and structurally sound wall, although it can also be mounted to a sturdy fence, shed, or garage wall.
The length of the greenhouse should face south with the supporting back wall/fence on the north side to provide plenty of sunlight on all sides.
North- or northeast-facing lean-to greenhouses will need to be well insulated to recoup the heat loss and are better suited to homes and garden walls with less overhang to allow the afternoon sun to hit the greenhouse, e.g., a low-roofline bungalow or away from tall trees/hedges.
Lean-To Greenhouse Uses
Lean-to greenhouses can be used in much the same way as a stand-alone greenhouse with different sizes and placements suited to different purposes.
For example, they can simply provide protection and display space for frost-tender plants or be scaled down for starting seeds and herbs.
Larger walk-in styles can be used as conservatories or a place for foodies to grow fruit and vegetables all year round.
Lean-To Greenhouse Advantages
- The solid back wall provides more consistent heat and protects plants from sudden temperature dips during winter.
- Provides wind resistance.
- Designs are customizable to the space available to you.
- Quicker access to water, gas, and electricity compared to stand-alone greenhouses.
- Wall support allows for greater vertical space for installing shelves, caring for tall plants, etc. without fear of wind damage.
- Provides architectural interest and may add value to your home.
- Allows for more comfortable, accessible gardening and maintenance during winter.
- Option to add home-door access.
Lean-To Greenhouse Disadvantages
- You may require a building permit.
- Installation can be expensive.
- A sufficient height/width is needed for the attachment wall without the obstacle of windows/doors etc.
- Can be costly to heat if a south-facing placement is not possible or if you live in a colder climate/zone.
- May not be suited to single-story homes.
- Certain crops may not produce as well due to the limited ventilation compared with stand-alone structures.
Lean-To Greenhouse Kits
If you have the luxury of being unburdened by limited wall space and obstacles that would require a custom-fitted greenhouse, a lean-to greenhouse kit is a great choice. These come in several heights and widths and are more cost effective than buying and assembling the materials yourself.
Best Lean-To Greenhouse Kit: Palram 4×8 Greenhouse
This 8 ft. (L) x 7.3 ft. (H) x 4 ft. (D) hybrid lean-to greenhouse can be assembled using simple tools and is perfect for small back yards, decks, and patios.
It’s designed with near-indestructible polycarbonate roof panels that block up to 99.9% UV rays to prevent plant burn.
The crystal-clear side panels provide 90% sunlight diffusion, and the integrated rain gutters allow rainwater collection for your irrigation needs.
A hinged door and roof vent also allows for adjustable heat, humidity, and airflow, and the structure can take winds up to 47 mph and snow loads up 15.4 pounds per square foot!
Are Lean-To Greenhouses Waterproof?
No greenhouse is 100% waterproof, but lean-to styles have the advantage of a solid fourth wall that makes them much less vulnerable to rainwater leaks and storm damage.
If you are building your own lean-to, growers on the Gardeners’ World forum simply recommend using a standard, colorless sealant between the wall and the frame, which works well “even on uneven stone walls.”
Do Lean-To Greenhouses Have a Back?
Most structures have no back to them as they are screwed and sealed onto an existing wall.
However, some smaller lean-to designs have a timber backing purely for aesthetics, and some manufacturers are able to fit glass back panels for greenhouses attached to a fence or rough wall.
How Do You Secure a Lean-To Greenhouse?
First, a pre-built base structure that is level to the ground is placed against your wall and screwed into approximately four or more pre-drilled wall studs depending on the design size.
Then, the glass/polycarbonate panes are assembled into a frame and the horizontal side panels are secured to the wall with screws before attaching a sloped roof to connected points on the wall.
Do Greenhouses Work in Winter?
Yes, greenhouses can operate in winter if you have decent insulation and a heating solution in place.
Mild southern climates can rely on the warmth of the sun a little longer into the cold season, but every greenhouse should have a portable electric heater or gas heating solution to anticipate unexpected frosts and utilize grow lights to further supplement lost heat and sunlight.
How Warm Will a Lean-To Greenhouse Stay in the Winter?
Greenhouses can typically maintain temperatures 30-40 degrees higher than the temperatures outside, though factors such as your chosen materials (plastic over glass or polycarbonate glazing for example) and the nighttime temperatures in your specific region will affect winter warmth.
As long as proper insulation and heating elements are in place, lean-to greenhouses may remain warmer for longer over winter since supportive brick walls absorb and trap the sun’s heat in the day before releasing it gradually after the sun goes down.
Do Greenhouses Protect From Frost?
Typically, yes. Most greenhouse constructions are designed to provide frost protection to your plants by sustaining temperatures at least 5 degrees higher than outdoors.
This applies to average winters but not very harsh, prolonged cold snaps.
Do Greenhouses Need To Be Heated?
If you are growing tropical plants with higher temperature requirements, trying to nurture vegetables or seedlings, or live in Grow Zones 1-7, your greenhouse will definitely benefit from additional heat alongside simple insulation measures.
Cheapest Way To Heat a Greenhouse
There are various ways to heat your greenhouse, but one of the cheapest methods is lining the interior with bubble wrap or moving your compost pile close to the exterior walls (especially if it contains plenty of chicken manure and fruit and veggie scraps) as the active microbial breakdown of organic materials can put out almost 100°F heat!
You can also make “heat sinks” (using the same principle as heat being trapped and released by the back wall).
Paint a 55-gallon water drum matte black, and place it along the north wall of your home to absorb as much daytime heat as possible before placing it inside your lean-to greenhouse at night for a slow release of heat.
How Much Does a Lean-To Greenhouse Cost?
According to landscaper Nieves Martinez at the cost comparison guide Fixr, the 2021 estimate for lean-to greenhouses is between $10 and $25 per square foot on average.
Designs can start from as little as $260 for mini styles to upwards of $4,000 for lengthier or tall walk-in lean-to greenhouses.
Can a Lean-To Go Against a Fence?
Yes, but the fence you fit your lean-to greenhouse to must be straight and able to take the weight of the frame and shelving mounted to it.
The chosen fence must also not shade the greenhouse and should be treated with sealant to prevent rot or deterioration.
Make sure drafty fences are fitted with a plywood sheet to provide a more airtight barrier between the fence and the greenhouse.
Can I Put a Lean-To Greenhouse on Decking?
Yes, in fact, mounting a lean-to greenhouse on an elevated deck can provide a great stabilizing foundation if your yard is uneven or on a slight slope.
It also has the added benefit of being placed high enough to help your greenhouse catch the sun better if it could be inhibited by a tall fence, tree, or other obstacles in your (or your neighbors!) garden.
Consider adding some type of solid flooring to prevent drafts and cold air from seeping in during colder months.
At half the depth of a traditional structure, lean-to greenhouses can be every bit as effective as the regular ones, just on a smaller scale.
With their lower material cost and easier installation, these are a great project for beginners who want to test the waters of greenhouse gardening!
Lean-to greenhouses come in all shapes and sizes to suit your budget and growing intentions (but best of all – to suit your limited space) and can be attached to any straight and sturdy wall or fence on your property.