If you’re going to start a survival garden (a good idea), then at some point in time, you’re going to probably end up thinking about building a greenhouse. The original greenhouse was invented in the ancient Roman Empire, as a way to grow cucumbers for Emperor Tiberius, when the climate wasn’t warm enough.
Essentially, any greenhouse is a passive solar structure, with the light of the sun warming the inside, even when it is cold outside. This makes a greenhouse an excellent survival tool, for growing food even when the outside ambient temperature is too cold.
What makes a true biodome different from a greenhouse is that it is a sealed environment, with the entire ecological system kept inside. Air remains fresh from the plant/animal balance; water is recycled through evaporation and condensation, and the plant life provides food for the animals, whose waste and decaying bodies give nutrients back to the plants.
When the term biodome is used in reference to greenhouses, this usually isn’t what it’s talking about. Instead, a biodome greenhouse is usually referring to a geodesic dome greenhouse, rather than a more traditional style. Geodesic domes are incredibly effective structures, using minimal material and providing maximum usable space.
Geodesic domes are hemispheres, so they are exactly half as high as they are wide. This can be improved upon, giving more ceiling height, by adding a pony wall for the dome to sit on. The dome itself can be made in a variety of ways, out of a variety of materials. The most complex is to build the individual panels out of a wood frame (or wood struts), with plexiglass or recycled greenhouse plastic for the glazing. This requires a radial arm saw, as the cuts have to be rather precise.
However, there are simpler methods of building a geodesic dome. Two of the most common are:
- Using 1” or 1-1/2” PVC pipe for the struts, with PVC vertices for joining them together
- Using wood struts, with rubber hose vertices for joining them together.
In both cases, the geodesic dome structure will need to be covered with greenhouse plastic. This is tougher and more weather resistant than contractor’s visqueen, which I have seen used for a variety of greenhouses. Considering the work that’s going to go into making the dome, the extra cost is worth it.
One of the critical components of constructing these greenhouses is the vertices which connect the struts together. You can buy commercially manufactured PVC vertices, which comes in 3, 4, 5 & 6 pipe versions. If you want to save money, another option is to heat the ends of the pipe struts and flatten it. Then, drill holes through the flattened ends, so that you can bolt them together. However, this will not provide as neat a geodesic dome as using the commercially manufactured vertices.
For geodesic domes made with wood struts and rubber hose vertices, making the vertices yourself is extremely easy. You merely cut ¾” hose to 6” lengths, drill a hole through the middle and bolt three sections of hose together. For cases where you don’t need to connect six struts, either ignore the empty rubber hoses or cut them off.
The other key component in geodesic dome design is the length of the struts. There are four basic styles of geodesic domes, referred to by the terms 3V, 4V, 5V, and 6V. These terms apply to the geometries of the domes, what shapes are used and where they go, in relationship with each other. You will need some help in calculating this, based upon how large a dome you want to build. Fortunately, there are a number of geodesic dome calculators available online, some of which are free to use. These will provide you with exact strut lengths, as well as showing the geometry and connections you need to use, to complete your greenhouse.
With the framework for the dome built, attaching the plastic covering is easy. For PVC pipe, clips can be made, by cutting short sections of a larger sized pipe. For wood struts, thin strips of wood can be used, capturing the plastic between them and the strut and stapling them in place.
While a biodome greenhouse will help to feed your family with delicious home grown vegetables it won't be easy to pack, carry or transport during an emergency evacuation. Consider getting any emergency food kit to augment your food supply. Depending on the size of your family each kit can provide at least 3 days supply of nutritious food and remains tasty even after 30 years.