Saturday, December 5, 2009

Garage to Greenhouse: A Photo Essay

"Turn the garage into a greenhouse?" my dad asked. "Where the hell are you going to park the car?" Well, I thought to myself, at least this year the garage will have a GOOD reason to be too full to fit the car in.

"You turned your garage into a greenhouse?" a farmer friend said, "What in the hell were you drinking?"

I'd been wanting a greenhouse of my own for 20 years, and for the past two years I had been eyeing up my garage. So, this year I hired one of my daughter, Holly's, friends--Joseh Hanna--to help and the first thing we decided to do was strip the garage down to its studs and beams, which, yes, required renting a couple of dumpsters. A funny thing I learned about renting dumpsters is that my neighbors wanted to contribute to filling it. It was a very slight feeling of "familial" annoyance and, oddly enough, warmth.

It was a scary feeling. Not only was I stepping off the edge of a cliff into a dream, but, like my dad pointed out, I was drastically altering a major structure. And where was I going to park my car anyway? Once the building was stripped down, however, I knew there was no turning back, and it began to feel exciting.

Around here (Southeastern Minnesota), you can't just run over to Menards or Home Depot and find the materials you need to turn your garage into a greenhouse. And the guys at Fleet Farm don't have any good advice to offer. You are on your own. I researched greenhouse supply companies on the web and, keeping my eye out for local businesses, I found Jr. Johnson Supply in Roseville, MN. That's where I found the materials for this polycarbonate roof. I rented a truck and we went to the Citie's "burb" to get it. My only other option would have been to order it from Washington (state), and the shipping cost more than the product--which, itself, was pretty expensive.

I used the internet a lot. I also looked things up in books. A good book for someone who is constructing a greenhouse is The Greenhouse Gardener's Companion, by Shane Smith. To convert the garage, I had to "imagine" what I was doing, rather than "know." Joseph, who worked for me, also had to have a pretty good imagination. I really lucked out with him.

These next few photos are of the inside of the greenhouse. The walls did end up coming from Washington, from a company called The Greenhouse Megastore that is a distributor for the Solex company, and that's is what I call the material on the walls--solex. It is a very thick double-layered plastic that arives in a roll. The green table in the middle of the room helped Joe and I get the plastic positioned. We stood the table near the outside corner of the greenhouse, put the four foot roll of solex on top of it, and then I held the roll steady while Joe pulled the end of the solex around the building. The material is held to the studs with neoprene screws--not cheap, and we bought every box Ace Harware had on stock to get the walls up.

Like most things, the solex is pretty easy to work with once you get the hang of it. I would recommend it to anyone who is building a greenhouse and wants a good plastic wall covering.

There is snow on the roof at this time. Once I start to heat the greenhouse, the snow will melt and the roof will be clear.

The solex is white and lets in about 75 percent of the sunlight. The clear polycarbonate on the roof lets in 90-95 percent. Eventhough the polycarbonate is clear, it is not a material you can see through, nor is the Solex. . .which means that if I put a hook lock on the door and keep a bathrobe handy, I can be in there naked--except for shoes, of course. Always wear shoes in the greenhouse. In the future, I will get a large cattle watering tank and fill it with water; thus, the greenhouse will also be a bathhouse. The water will help heat the building, and if I use biodegradable soap, I will also be able to serve the water to the plants.

The pots in the front contain herbs that grew outside all summer: calendula, chamomile, chervil, parsley, chives, sweet marjoram, lavender, and just a bit of rosemary. Amazingly, all of these herbs have frozen solid repeatedly, but once they thaw, you could never tell. As long as they thaw, they will keep growing.

Here are some photos of the outside of the greenhouse:

As for heating the greenhouse, that will be another "inventive process" because rather than slapping in some kind of furnace, which would take about a day, I will be building a solar radiant system myself with only a vague, general blueprint to follow. I already know that I will need some kind of gass or kerosine heater in the meantime, because it could take me a year to get the solor system running, but once it's in, I will be able to enjoy years of heat that I will not have to feed continuously at a high and unpredictable cost.

To build this system, I will need to install a double layer of R-20 insullation four feet up the sides of the walls. Then I will front that with a thin layer of plywood or some other material. Attached to the plywood between the studs I will run a zig-zagging line of high pressure hose. The hose will be attached to a 20-30 gallon hot-water heater "storage" tank on one end, and to a solar panel on the other end. (The solar panel will be located on the front of my house, facing south.) The water tank will also be attached to the solar panel by high-pressure hose. The solar panel heats a solution that is stored in the tank, and the solution is pumped throughout the lower walls of the building, producing heat. The system can be automated by a thermostat. I will likely have a couple of back-up batteries to store energy (generated by solar panel) for the days, and weeks, of overcast skies that we generally have in the winter here.

The greenhouse will need to be ventilated, and my plans are to install both north and south-facing, 16" exhaust fans near the roof peaks to blow hot air out; intake vents near the floors on the east and west-facing walls will bring fresh air in. This system can also be automated with a thermostat. A ceiling fan will be located in the center of the greenhouse to pull cool air up in the summer, or blow warm air down in the winter. A good ventillation system is extremely important in greenhouses to prevent diseased plants and/or dehydrated crops.


  1. An excellent example of what a little vision and ingenuity can accomplish! Good luck in the greenhouse and keep up the good work!

  2. I am SO glad to see your greenhouse/garage. I scored some cheap, unused 4x8 white (opal) triple wall polycarbonate and I want to put up a greenhouse from all our scrap lumber but was worried about the lower light transmition of white polycarbonate. But I live in CO where too much sun is always an issue. I hope your greenhouse/garage experiment is going well :)

  3. I am sooooo inspired :) I have a 2-car garage "around back" that I never use and have ALWAYS wanted a greenhouse.
    I 1) lost my job due to the economy 2) got divorced 3) was diagnosed with MS 4) moved my only daughter off to college within a 6-month time frame and I am so excited to research how I too may begin to "turn my garage into a greenhouse" !!! This may be just the thing I needed to provide myself an income by working from home :) It will take money to get it going, but I am sure that if it's what God wants me to do, He will supply the funding :) Thank you for the inspiration!!!

  4. I too am interest in a greenhouse...but my house faces south... just by stumbling through the world-wide web I found this site and would absoulte love turning out attached two car garage into a sunspace/greenhouse! I am very inspired by your imagination and courage... now, if only my husband will let me...hmmm :)