How did I end up with a Lean-to greenhouse?

In my early twenties, I moved out of the city with two small children and another on the way. My (then) husband and I purchased a small house. It was a 700 square foot “cottage,”. When things are tight, you can call it a “cottage” and it somehow makes things seem more romantic. In the wetlands of Virginia Beach, it was an “as is” charmer of a home.

One of its more sturdy, well-built features was a 10 x 12′ back deck.

Location, location

The first summer there, we enjoyed the deck a few times. It was an excellent location, right off the kitchen. However, we realized that it got too hot to enjoy it much on summer days, when the sun went down. By then, mosquitoes would be so thick that no one in their right mind would hang out there unless they had an insect screen or a death wish.

When I read of attached greenhouses in a country-living type magazine, I was intrigued.

The southern exposure was ample in that location. It gave us a place to start all our garden vegetables and other plants in early Spring.

Dreams of health and vegetable wealth

Within a few weeks time of reading the article, we secured a cache of storm windows. They came complete with screens second-hand. We now could have a greenhouse and (by opening the screens) an outdoor “room” for summer. All without sacrificing ourselves on the altar of biting insects.

A lean-to greenhouse is passive solar heating for living space

The first roof we had on the attached greenhouse was the only new building material we bought: corrugated plastic. Because it was clear, the roof allowed ample light and heat into the space on even cold-but-sunny days. As long as the sky was clear, and the temperature was above freezing, our house was comfortable (65 degrees+).

Gone were the days where I’d have to stoke up the woodstove first thing to get us warm. Nor would we have to use the expensive and dusty baseboard heaters. Now, I could just open the back door into a world of greenery and warmth.

Within a half-hour or so, the entire house would be well-heated by virtue of the sun.

Passive heating, Act II

We were so impressed with this “free” heat that a couple of years later, we knocked down a shed next to the aforementioned lean-to greenhouse. Adding “glazing” (windows) to the other half of the southern wall made good sense. Then, we installed a large set of wooden French glass doors in the girls’ south-facing bedroom.

Where before the kids had only one small window that was 4′ off the ground, the kids’ room now had a beautiful view of the back gardens. Access to the backyard via a small deck with a grapevine-covered pergola was easy.  A family member predicted the kids trying to “escape,”. Now, though, with such a nice view, there was nothing to “escape” from!

Glazing/windows on the south side for the win

Adding glass doors on the south end was inexpensive, but a drastic change. For less than $200, we purchased the doors second-hand, framing (to reinforce the wall) and a gallon of paint.

This transformed an admittedly dreary little room in our post WW2 cottage into an extension of the garden.

On sunny days, the house heated itself quite well. Instead of waiting thirty minutes for the greenhouse to heat everything, it took just fifteen. And then, it was cozy and warm.

French doors=heat gain and fire exits

Plus, we now had one more escape route if there were ever a house fire. This is always a consideration when one heats their home with a wood stove. Aside from having working, easy-to-reach windows, an exterior door for every 300 square-feet of home space is recommended for this purpose.

Begin again

The benefits of the lean-to greenhouse were many; it was in our plans for the next home, in Scottsville. It just took a little while to get around to it.

The biggest considerations for this space were size, materials, and not blocking the already-present passive solar attributes of the house. (The passive solar benefits from glazing on its South side during initial construction were numerous).

We knew we wanted a larger greenhouse than the previous one, which was 10 x 12′. We planned to double that, for home vegetable consumption and a small nursery business.

Careful observation before construction

Inhabit or work in a space for at least a year before making any large investments or improvements there. This rule of thumb applies not just to garden work, but also hardscapes, and buildings.

The depth from the back door of twelve feet was decided by observing several winter solstices and the amount of heat gain we wanted from the project. Generally, you want a lean-to growing area to be twice as wide as it is long, and only deep enough to allow full penetration of the sun during the coldest parts of the year.

This greenhouse is on the south of the house.

It makes no sense to build one anywhere else, or facing any other direction (in the northern hemisphere. In the southern hemisphere it is the opposite),

For best performance, free-standing greenhouses should also be aligned East-West, with the widest side to the South. Though they are standard in commercial operations, they are at least doubly hard to keep evenly heated. In colder temperatures, they won’t be buffered from North winds like an attached greenhouse naturally is.

Experiences with hoophouses and freestanding greenhouses

We found out from building a quarter-hoop greenhouse in Virginia Beach that freestanding structures’ performances are less user-friendly. At 12 x 30′, it was ample-sized, but it was 75 feet from the house, and it got cold easily.

Even though it was insulated with foam panels, and a buffer of small trees and grapevines set twelve feet from its back (both on the north), nothing shaded its East or South sides. We could grow tomatoes in January, but only if we used an auxiliary heater.

Though our electricity cost didn’t go up too much, and we probably ate more than ten dollars’ worth of fresh tomatoes (the cost for the additional electricity), the system was not as sustainable as a lean-to greenhouse.

Why doesn’t everyone have a sunroom, or attacked greenhouse?

The reason I think attached greenhouses are just not as widespread as they should because you don’t see them in commercial applications.

Seeing their use commercially popularizes the general concept of greenhouses. They are not widely constructed in optimal locations, with the best floor-to-glazing ratios.

However, for anyone with space on the south wall of a building and a desire to garden beyond the regular growing season, a lean-to great sense.With good planning, even if you do not intend to grow and sell plants, the amount of money you save on heat could pay for the space in as little as one to three years.

The Horseshoe Hill Lean-to Greenhouse

Our second attached greenhouse was built in Scottsville at Horseshoe Hill. It began as an insulated, poured concrete pad with some tools borrowed from Michael’s place of work (i.e. the whacker packer…what a name for a tool!) and help from our local Barter network.

We moved most of the gravel that was originally flooring in our barn house to delineate the space a few years before. This gradually compacted the area, enabled seasonal observation, and then, on a beautiful late-winter day, we finally poured cement there.

The Big Pour

The day of the actual pour was very exciting.

Several people showed up (unlike when we poured the floor for our house back in September 2001). They brought bread or cookies (thanks, Marca-Maria and Olivia!) There was a moment of panic when we realized that the form walls were buckling(!!!)

Quick thinking and shoring up minimized any concrete casualties (the first of which would have been a hillside garden getting unintentional paving).

By the end of the day, we had a smooth concrete pad with a central drain to build upon. (Thanks, Gary and Alec!) We were ridiculously happy that January day, spraying the water and watching it go into the hole, as gravity and planning dictated. Same wonderful, predictable result every time.

We were able to get some left-over beams from our friend Alec’s new timber frame house. He sold us some nice windows he’d decided not to use in that same building. These double-paned and crank open windows are nicer than what is in our actual house.

Slow and Steady builds the greenhouse

Throughout the summer, Michael and I worked on the space. We covered the framing with plastic for a temporary greenhouse effect. This was for our Spring herbs and vegetable starts, and for heating the house. 

We were able to make back most of the materials’ investment in plant sales that spring. This is when we decided to put a shingled roof on it, making it more a “sunspace” than a technical “greenhouse.” Thank you to David and Jennifer for helping with that!

I think they were happy to learn how to roof with shingles, since they were planning to build a cabin in their backyard. They were going to be doing a similar-style roof.

Our aforementioned friend Gary, along with Woody and Giovanni, helped with the windows. Their assistance helped us consider which way we wanted them to crank open, with regard to the direction of the prevailing winds.

The choice to roof or not to roof, that was the question

Our greenhouse, appears more like a sunroom, because it now has a roof.

Mark Freeman’s book on greenhouses informs that space with insulated roofs attached on the south capture and contain heat most efficiently. Even more so, in fact, than clear, non-insulated roofs like we had before. Clear roofs allow more heat to escape in the winter and let too much heat in in the summer.

A roof and screens make this a four-season room

The shade created in the summer by the insulated roof made an ideal place to dry herbs, or keep perennial starts somewhat shaded (reducing the water needed for them till they are planted). Depending upon your latitude, a clear roof is more detrimental than good. In Virginia, it is wholly unnecessary. A solid roof shields the space from sun in the winter and is much stronger during hurricane season.

In the winter, the greenhouse space makes an ideal place to over-winter hardy annuals like Cole crops, perennials and water or house plants.

This sunny space (with awesome floor drainage!!!) was great for art projects like papermaking in the winter. With long wide tables free from plants, it was nice to exercise creativity of a different kind until the growing season began again.

J arranges flowers in the early morning light of the greenhouse.