Coldframes are a really simple and effect way to use the sun and grow abundance. Almost as soon as I arrived to the village I saw the need for at least one coldframe and set about designing and building it.
Basically it is a hole in the ground filled with carbon and nitrogen (compost) and covered with a transparent material (glass/plastic)..
This will work almost anywhere but with a bit of thought and design one can extend the growing season by many months. Digging into the ground takes advantage of the earths stable temperature. As the compost gets processed it gives off a substantial amount of heat to the soil, and the transparent covering allows the plants light and keeps the plants nice and warm. By opening and closing the lid you can easily regulate the temperature on hot days.
I'm not actually sure if this can really be called a 'cold'frame as we are trying to keep it warm but that is how I've heard it called . Anyway, Its a basic method of passive (solar) heating that we should be using a lot more to grow an abundance and variety of crops. Now we mainly use ours for seeding onions in the spring and lettuce in autumn, though we have started perennial onions,sunflowers, pumpkins, courgettes and a lot more. The plants love it, shooting up when everywhere else is frost and often touching the glass and filling the space before it is time to transplant them.
When choosing the location for this coldframe we had to factor in orientation and slope to collect as much sun as possible, distance to gardens for transplanting and we wanted it to be close by and on a route we often use so we could not forget to water it or open it on the warm sunny days.
So, we dug a hole.
Not the first and definitely not the last, we are forever finding reasons to dig.
The hole, aswell as the very first greenhouse and coldframe, and in the background the main communal workshop.
We have a lot of old windows stored so I found 4 that could be attached together to make one for each side and then from recycled door posts we built a frame to hold them at the right angle.
Below ground the frame was surrounded with porous cal stones, called 'tosca' here, which is great at insulating, and above ground with normal stones to absorb the suns heat.
The stone work almost complete.
We filled the bottom with smaller heat retaining stones and built two towers in the center of each side to fill with soil and allow the worms to migrate to the compost layer.
Starting with a thick layer of leaves we piled on the compost ingredients.
Not sure why we have never taken a photo of the fun compost step but it envolves as much tasty mixed fresh manure and straw as we could dump in the hole and still level off with space enough for the top ~7cm of quality finished compost and potting soil.
The windows attached, the stone work finished and all the wood drenched in recycled oil, it was then ready for growing abundance.
So that's how we built a coldframe five long years ago, when we were just starting the adventure of living here. Since then it has served us very well, helping us produce enough food to now be ~95% vegetable self-sufficient. Unfortunately, over the years, some of the glass has broken and been quickly replaced with plastic. Before too long we will replace the windows and oil everything again in preparation for the next season.
We could have put our time and energy into already building another larger greenhouse, but at the time we opted to go for this smaller simpler structure, that still has lots of planting space, so we would have something ready for the following season. Another option was designing an active heating system like a rocket stove mass heater, but we thought it an unnecessary use of the wood and time to maintain a fire and heat all winter long. We have since built a larger greenhouse connected to a living space and we will soon build a rocket stove there. A post will be made when that happens ;)
How much food are you going to grow this year?
More to come on our life here in an officially abandoned Spanish village, all the permaculture solutions we come up with, and how we practise eco-anarchy in the face of dumb bureaucracy.
All criticism welcome. I would like to improve my informative writing as I have much to say!