Cold Frames:

A cold frame can extend the growing seasons in spring and fall.

I have created easy frames from old bricks or cinder blocks stuffed with straw and placed an old glass framed window on top. This method should be used with care as the window could break and then you have the difficult job of picking up glass shards in the garden. But, it does help keep seedlings warm and protected from late frosts or snow. Another method I have been using every year is straw bales and corrugated fiberglass attached to a wooden frame that my husband made for me. I purchase enough straw bales in the fall to cover the back side plus one on each end and an extra for “stuffing” in the open spaces. Try to place the back part of the straw bales on the winter wind side and the “glass slant” on the winter sunny side. Come summer, the bales can be broken down and used as a top dressing on the garden beds to help retain moisture and keep the soils at a moderate temperature. One other cold frame method is using a house or building wall with winter sun exposure and then just building up the sides to support the glass. If the building is a darker color, the thermal heat created will help the cold frame stay warmer. There are lots of ways to increase thermal heat in a cold frame, but I am just trying to keep things simple.

The beauty of using a cold frame in the spring is that one can plant cool crops earlier. This is a benefit for those who live in the Southwest where winter and spring can struggle with each other for months, and then all of a sudden the heat index climbs quickly and cool crops begin to bolt. It always brings a smile to my face to watch the miracle of seeds sprouting through soil inside a cold frame, while there may be snow laying on the outside. I am able to get a head start on radish, spinach, beets, green onions, carrots, leek, chard, peas, and other crops within the frame. Come spring, I can move the leek and chard to other locations. It saves me space inside my house on my heated seedling mat if I can start the cool crops outside. Also when my pepper and tomato plants become too large for my heat mat space, I can place them in larger containers and sit them under the cold frame to harden off.

My husband welded a brace that I can hold up the frame and allow heat to escape if need be. Although a cinder block, on end, can also hold up a frame. I would use at least two, depending on the size of the window or frame. And never leave the frames open if it’s windy, a gust can cause them to shift, fall, and crush the plants. I have left my frames open all day and would find a hen laying an egg in the warm, cozy space while helping herself to some fresh lettuce! Come time to plant the regular garden areas, some of the cooler crops will have bolted, like radish, cilantro, and possibly the lettuce. I leave the flowers on, as I plant heirloom crops, and will save the seeds. The bees like to fly in to the open frame and work the flowers, giving them an earlier start to their own harvest season.

Come Autumn and the increasing chance of frost, I recreate the cold frame with new bales to cover a section of plants I am trying to preserve a bit longer. Tomatoes tend to be too tall for this idea, but creating mound like walls around the tomatoes with straw or pine needles, then placing a sheet of Agribon over the top of the tomato plant should supply you with extra weeks of tomatoes! Make sure to weight the Agribon down with rocks, bricks, or some other heavy objects so it doesn’t fly off in the wind. You can wrap each tomato plant separately and hold them together with clothes pins or just tie the ends together to create the individual warming blankets. I had some extra sheeting that I laid over my swiss chard this winter and despite heavy snows and 7 degrees F, I still was able to harvest chard, although it was flattened a bit by the snows weight. I purchase my Agribon row cover from Johnny’s Seeds. Agribon is a great product. I have been using it for years and it always amazes me as to the protection it gives under harsh conditions.

If you only have space for a few plants, another fun trick is creating cloches. A true garden cloche is very pretty. It is a glass bell that fits over a plant creating a warm microclimate. It protects plants from frost or from one of those weather events where it becomes too cold or too windy to support a young plant. If you live near a second hand store, a Goodwill, Salvation Army, or any thrift store, take a look in the glass area for the thick walled flower vases. These are fairly cheap and you can find them with regularity. Just turn these vases over on top of your young plants to keep them warm. I have even planted seeds directly in the dirt and sat these upside down on top of the seeds after watering, to retain moisture and heat. It becomes a mini cold frame! Just remember that if it is going to be a fairly warm day, it would be good to remove the cloche so that you don’t cook the plant.

Since I live in Prescott, AZ, I have already seeded my cold frame this past week. The worms were busy in the soil, so I made light furrows with my hand tool to minimize disturbing the soil building process. I seeded, then lightly shook small bits of straw over the top, watered, and closed the lid. If it gets real cold again, I will probably add a sheet of Agribon on top of the seedlings and keep the lid closed as well. I have been watering with rain/snow melt from my catchment tank. If you do not have a catchment tank, try catching water from your downspouts in some buckets. The water is great for indoor plants as well as garden plants. I keep a “plastic” garbage can (with lid) in my garden. I then fill the can with the rain water from the regular tank. This enables me to just grab a small bucket of water for individual plants when needed. I have used horse troughs for water holding in the past, which I will cover in another article.

I hope you have enjoyed these ideas and that you will be inspired to create a cold frame and increase your food harvesting capabilities!