Build Your Own Recycled Greenhouse
Purchasing a pre-built greenhouse can be pricey, but with a bit of ingenuity and handyman tact, you can construct a greenhouse yourself from recycled materials. See the above samples for greenhouses built out of old windows and storm doors!
Others have built greenhouses from recycled bottles, curved PVC pipe with a plastic cover (this doesn’t hold up well to winter weather), and pretty much anything made from glass!
Building the House
Finding materials does not need to be difficult process. Keep an eye on your local classifieds for windows and doors, stop in at an auction, or check in with suppliers of recycled building materials. Maybe you know someone who is ripping down an old building and has leftover materials, or you could spend the year hitting up recycling bins for bottles (invite the friends over for a few BYOB parties and collect!).
An important consideration for building a greenhouse is heating. People have used a variety of methods including small fan/heater combos (can usually be purchased for less than $30), building the greenhouse where heat from your home or other sources can be accessed, or the “passive” approach, using materials that absorb heat during the day and omit the stored heat during cooler hours.
Stored water is a common “passive” method of greenhouse heating. By storing 2 gallons of water (in darkly painted containers) for each square foot of greenhouse, you can absorb heat during the daylight hours and then omit that heat throughout the night (just be sure you keep them away from the colder sides and walls of the house). Water is also a great way to help add humidity.
Another passive method uses rocks. Rocks are great heat absorbers, as are bricks (which can be painted black to absorb even more sun). You could use bricks as surfaces for plants, wall dividers, or to construct a solid wall on the colder northern side of the building.
Most importantly, you should keep track of the temperature in your house to measure how well your methods are working. Don’t be afraid to experiment with a combination of methods. As long as the house is well constructed and insulated, passive methods have proven successful for most homemade greenhouses.
To insulate a greenhouse floor, use a layer of pumice stone (you can dig a trench around the outside of the house and fill with stone to help insulate even further). This stone will keep frozen ground from cooling off all any stored heat you’ve worked to create, and will also absorb and release its own heat! You should also be careful to check and seal cracks or divisions in the walls and roof.
Other Tips & Tricks
The north side of the house will always be the coldest because the sun does not directly radiate from the north. Sometimes it is best to build a solid, insulated wall on the north side to hold more of the heat in the house. Knowing the north side is colder, may also influence you to place your passive heating materials closer to the hotter side of the building to absorb more sunlight and heat. You could place a “work table” in the house and use the colder/shaded north side of the building to do your planting and pruning.