The reason many people choose to build a greenhouse on their homestead or for off-the-grid living is simple: Winter in the cooler climates of the world makes it difficult to remain self-sufficient.
Hens stop laying as prolifically when it is cold, cows and goats produce milk taste that doesn’t taste quite as good, and there is no fresh produce from the garden. However, you can fix the problem of not having fresh produce by building a greenhouse — even if you can’t get your hens and milk animals to improve through the cold months.
There are several things to consider before you build that urban greenhouse:
- What are the regulations within your township or city as well as county?
- How much space do you have to devote to a greenhouse?
- Is the ground level?
- What kind of greenhouse will you build?
- What will you keep in the greenhouse?
There are hundreds of websites that promote specific types of DIY greenhouse types, kits and methods of building that say that you can build one for less than $50. I even found one that said you could build a greenhouse for less than $5. I find that one a bit difficult to believe.
The idea behind building a greenhouse is so that you can use it for a long period of time. This means that your greenhouse is not going to be cheap and inexpensive, since you will want to use materials that will last.
I do not recommend using clear plastic bottles or PVC pipes to build your greenhouse, although both materials may last a few months if you’re just wanting to start your plants that will be set in your garden as seedlings.
Clear soda bottles (aka PET bottles) are the suggested material of many websites for building a greenhouse. However, these bottles are made with Bisphenol A (BPA) plastic, which is known to be dangerous. Unfortunately, all of the studies done have been performed on the fluids inside the bottle, so we aren’t entirely sure if the condensation that may form on the bottles used for greenhouses contains these harmful chemicals as well. Another reason not to use plastic bottles is that the plastic expands and contracts as the temperature changes. In colder weather it could leave gaps, allowing delicate seedlings to die. In hot weather, the plastic softens, and any sudden change in temperature, like the spray when watering your plants, can cause the hot plastic to instantly contract and crack, which will reduce the integrity and usefulness of your structure.
PVC pipes have their own problems, although that doesn’t stop hundreds of websites from suggesting them as the base material for building a greenhouse. PVC pipes are used for a type of backyard greenhouse called a hoop house, because you can bend it so easily. This flexibility is its hugest flaw. Because PVC is so flexible, the hoop house design doesn’t last long and won’t stand up to even moderate winds, as the piping is not designed to put up with direct sunlight or high heat. The cost required to reinforce a PVC hoop house could put the cost close to a proper stick-built greenhouse.
One of the better materials for a small urban homestead or backyard greenhouse is actually old single-pane windows that can be reclaimed from houses when windows are replaced or the building is torn down. Unless you are very fortunate to find someone willing to give you these windows, you should figure on spending a fair bit of money on procuring them. You’ll also need to purchase wood for the framing, cinder blocks or cement mix for stabilization and screws for assembly.
As you can see by all of the above, building a greenhouse is not an inexpensive project – not if you intend it to last more than a few months. An actual stick-built greenhouse will last years but it takes planning and a moderate budget. Here are a few more things to consider:
- Will you build above or partially below ground? The pit greenhouse was developed several years ago to allow greenhouses to be used in cooler, mountainous regions.
- Do you have an already existing outbuilding you can repurpose into a greenhouse?
- Is there a clear space that has a southern exposure so that your greenhouse will receive the maximum amount of sunlight available in your region?
- What is your budget for building your greenhouse – and do you have the skills?
Let’s discuss each of those decisions you will have to make when deciding to build your greenhouse.
1. Above or Below Ground?
According to a 2002 bulletin by the Benson Agriculture and Food Institute at Brigham Young University, a pit greenhouse was constructed to “utilize nature’s resources to provide a warm, stable, well-lit environment for year-round vegetable production.” It works because the “frost line” is at or around the 4-foot mark (check your location for specifics). A pit greenhouse is much more efficient than above-ground greenhouses in colder climates since the ambient temperature in the earth is between 50 and 60 degrees Fahrenheit and only needs to be raised 20 to 30 degrees to bring the air temperature up to the optimal 80 degrees for plant growth. The additional heat radiating through the clear plastic or glass of the roof is absorbed into the earth and released through the night to help keep the plants warm.
An above-ground greenhouse has no internal ambient temperature to rely on. Therefore, you will need to raise the temperatures back up to the optimal 80 degrees each day. This requirement reduces the production of your plants and holds their growth back. If you live in a climate where you will have winter weather and the temperature will drop below 45 degrees Fahrenheit, you will probably want to incorporate some type of heating unit to eliminate that requirement and protect your plants from frostbite and freezing during the coldest months.
2. Existing structure?
If you have an existing outbuilding or a lean-to patio attached to the south side of your house, either option is viable. Obviously, the roof of the existing structure will need to be replaced with either glass or some clear plastic corrugated sheets to allow sunlight inside. Large expanses of wall on the south side may need to be replaced with windows or the same plastic sheeting used for the roof. Your lean-to patio can be enclosed with plastic sheeting as well to create your greenhouse space.
3. Space and Exposure?
A clear space is sometimes more difficult to find when you have property in the country. The ground may be clear and it may be a southern exposure, but there will inevitably be trees that will cast shade on your greenhouse. You should choose a spot that has no trees surrounding it so that you don’t have to work so hard to keep the temperature high enough in the greenhouse. The place you choose to build your greenhouse should be as level as possible, as well. If it isn’t, you will need to level it before beginning your construction project.
4. Budget and Skills?
The budget and your personal skills are often combined. Your personal skills, and those of your family and friends that might be helping you, should be considered well prior to choosing your structure and materials. Basic construction skills such as reading building plans, measuring, cutting wood to length, hammering nails and using electric tools are essential to taking on the responsibility of constructing your own greenhouse. You may also need to know how to run electrical wiring for lights, your ventilation fan, and automatic misters if you choose to install those. Some plumbing knowledge would be good as well if you choose to install a hand washing sink so you don’t have to return to your house all muddy and grimy from working with your plants. So, if your skills are not up to following your building plans, you may need to hire someone to do it for you.
You can purchase greenhouse kits at several places on the Internet, they can be found by doing a simple Google search for “greenhouse kit.” I have found the kits will run anywhere from $300 to $6000+. The kits usually tell you exactly what is included in the kit, but it probably won’t include everything you might want for your greenhouse.
Another choice besides purchasing a kit that you will need to assemble is to purchase or find a plan for a greenhouse. I was able to find plans for as low as $5 for the ability to download a clean PDF. If you choose to go the route of purchasing plans for a stick-built greenhouse, you will need to determine how much the materials will cost. Remember that plans can be modified, especially if you are changing the size, but not so much that it can potentially harm the stability of the structure.
I hope that this article has offered you good information on what building a greenhouse to extend your growing time entails. I want to leave you with one last thing before I close. There is a website that I found during my research on building a greenhouse that offers a great deal of information that I had not had prior to building my own greenhouse. Fixr has a cost estimate form, which was very helpful to me and gave me a good estimate of what size budget I will need for my dream greenhouse. For now, I will have to make do with the small greenhouse I built. Even this much is better than nothing.
What advice would you give someone building a greenhouse? Share your tips in the section below: