One overcast afternoon in Durango, my roommate and I were organizing a pile of scrap wood and old aluminum framed windows. The orange and yellow aspens around us were whispering of the looming winter and the gray woolen sky was threatening of snow, and we were getting ready to grow some food in our garden. Sound strange? While most people in town are covering their gardens and prepping them for next spring, we are laying down fresh compost and sowing seeds in hopes of having fresh greens throughout the winter.
I became inspired to try and extend the growing season for my own garden after taking a tour of the 4-season demonstration greenhouse the Fort Lewis College Environmental Center is currently experimenting with. The dome shaped greenhouse is equiped with insulation around the base to keep frost from creeping in through the ground, a 900 gallon tank of water to absorb heat during the day and radiate it through the night as well as solar powered fans that blow warm air underneath the raised beds. Having virtually no budget to work with and no hopes of putting an elaborate green house together, I did what college students do best and started doing research and scavenging for materials. If we chose hardy winter crops we would only have to keep the temperature inside our structure above 32 degrees. I decided to build a “cold frame” which is essentially a green house that is about 18”-24” tall with a glass roof and wooden sides. I went with this idea because of how adaptable it is and I could get most of the materials for free. After acquiring two aluminum framed windows that a classmate had lying in his shed and six 8 foot long 2×8’s which were remnants from the neighbors deck they had torn down. My roommate and I then built a 7 foot by three foot box that stood about 16 inches tall and the windows fit perfectly on top of. This design allowed us to grow about 20 square feet of greens during the colder months of the year. We placed the cold frame in the section of our garden that would get the most sun and buried one end a couple inches to make the frame slightly south facing so it would catch more sunlight. Then we dug a trench about 6 inches wide around the frame and packed it with straw to stop the frost from creeping in through the ground. On the inside of the cold frame we placed a few gallon milk jugs we had spray-painted black to capture the heat from the sun during the day and release it at night. Then we chose some hardy cold weather crops like lettuce, Swiss chard, kale, spinach and scallions to plant inside the cold frame. We chose these crops because they can withstand much colder temperatures and they need much less light to grow. So they are very appropriate for the cold nights and short days we have here in the San Juans.
It is now early December and the romaine lettuce and the mesclun mix we planted are flourishing. It seems that the insulation we put in the ground and other precautions we took to keep the temperature up at night was really working. One night we got about 5 inches of snow and the next morning when we brushed the snow off the cold frame we found it to be 40 degrees and steamy inside.
After seeing the results from the simple cold-frame we constructed I would definitely recommend those out there who love gardening and growing food look into building their own cold-frames, row covers, or a greenhouse in their back yard. There is a ton of information out there on how to extend the growing season in your area either by investing in an elaborate greenhouse or using the simple measures I took. Let me tell you there is nothing more satisfying than pulling a fresh and organically grown salad from your backyard in December. If you would like more information on how to extend your growing season or what crops are good to grow in the winter: the internet, your local library and the FLC Environmental Center would be great places to start looking.
Good Luck and Enjoy!
– Alex Pullen