We have two cold frames we are very, very happy to own. They provide kale, spinach, chard, lettuce, cilantro, parsley, carrots, etc. all year-round. We feel fortunate to have this blessing.
We are looking forward to the Spring of 2014 when we hope to add a Walipini (an underground greenhouse) to our food growing endeavors. So, just FYI, here is a link to an informative article and video on how to build one of these structures for $300. Read about the Walipini here.