An attached, lean to greenhouse can be a relatively inexpensive way to have a hobby greenhouse.
That type of greenhouse comes with a few disadvantages compared to a freestanding greenhouse structure.
But it offers several distinct advantages, too.
Lean to greenhouses are sometimes called ‘half greenhouses.’
That’s because they are usually attached to another structure at the point that would normally be the roof peak of the greenhouse if it were a freestanding structure.
That makes it appear as if the greenhouse were sliced in half.
And in fact, the ‘half a greenhouse’ nickname does speak to one of the shortcomings of lean to greenhouses – space.
A lean to greenhouse tends not to have lots of interior space.
But it’s all relative, because certainly there are lean-to or attached greenhouses with greater interior space than some of the more diminutive freestanding structures.
But if you yearn for a large, cavernous greenhouse, with room to grow just about anything you could think of, a lean-to is probably not for you.
Since one entire wall of a lean to greenhouse is the solid wall of another structure such as a house or garage, the amount of sunlight entering the greenhouse can be an issue. For that reason, the orientation of an attached greenhouse is particularly critical.
Having the greenhouse attached to the north wall of a structure (in the northern hemisphere) would be a bad idea. Not many plants would do well with the relatively low levels of light that would be entering that greenhouse – particularly during the winter when the sun is angled low to the south.
A southerly exposure would be optimum.
East or west exposures wouldn’t be perfect, but would be preferable to a northern exposure. (Most plants will do better with an eastern exposure than with a western exposure because the morning sunlight allows photosynthesis to kick into high gear early in the day, rather than later in the afternoon.)
Temperature control and ventilation can also be more difficult with an attached greenhouse.
Options for placing ventilation inlets and outlets are more limited. And the wall that the greenhouse is attached to can serve as a heat-sink, drawing heat from the greenhouse when you’re attempting to heat it, and adding heat to the greenhouse when you’re attempting to cool it.
The extent to which these problems affect your greenhouse, of course, are influenced by the size, color, and material of construction of the supporting wall.
Lean to greenhouses can also offer some real advantages to a hobbyist greenhouse grower. The most obvious is cost.
Obviously an attached greenhouse offers an advantage in the amount of materials required to build it. After all, you’re able to dispense with an entire wall. But you can save costs in other ways, too.
If you can tap into the water and power systems of the building to which you’re attaching the greenhouse, then you’ll be saved the cost and effort of running power and water lines to a freestanding greenhouse.
It might even be feasible to tap into the heating system of the ‘mother building,’ saving the cost of a separate heating system dedicated to just the greenhouse.
And the disadvantage of limited space that we discussed earlier? Well, that could actually work to your advantage if you have a very limited space in which to place a greenhouse. By merging two structures into one, you eliminate the space-eating buffer zones that would be required between two separate structures.
So if you’re very limited for space, a lean-to greenhouse could actually allow you to come out ahead in terms of the amount of greenhouse square footage you end up with.
Imagine that it’s a frigid February day.
The snow is piled up a foot deep on the ground. And the icy north wind is gusting with a ferocity that snatches your breath away. You’re cozy and snug inside your house, of course.
But you have an urge to go putter in your greenhouse for a while.
Does that mean that you have to throw on a coat, tug on your boots, trudge through the snow and be chilled to the bone by the wind?
You just open the door that leads from your house (or garage) right into your attached greenhouse - maybe even still dressed in your robe and slippers! And putter away to your heart’s content.
How’s that for convenience?