Time to build a cold frame

Are you ready for the growing season to end? Or would you like to extend the life of some of your vegetables? At our house, we are definitely ready to stop mowing the lawn and doing other not-so-fun maintenance chores. At the same time, I am not looking forward to weaning myself off the home grown tomatoes, peppers and eggplant.

It probably isn’t practical to attempt extending the warm season crops, even though there have been many years when my husband and I have dashed outside with rolls of plastic and a frost on its way. These annual plants have a life cycle after all and are probably nearing their end. My warm season vegetables have been badly ravaged by insect and disease this year, so it is probably time to say goodbye to them.

For my newly planted cool season vegetables, however, that’s another story. Did you know some cool season vegetables, like broccoli, cabbage, onions, lettuce, peas and spinach enjoy daytime temperatures as low as 40°? They can also survive a mild frost.

You can extend the growing season this fall by using a cold frame. This is an easy weekend project that will benefit you now and for years to come. It is just perfect for smaller plants, like salad greens and radishes. You can also use it next spring to harden off your seedlings or get an early start on the growing season.

A cold frame is often constructed from wood. You can customize the size to fit your needs. Frames that are 4’ x 4’ or 3’ x 6’ are common. The back of the frame should be about six inches taller than the front, so you can prop open the top on warmer days. The hinged top can be constructed with a double layer of polyethylene film. Place the cold frame on level ground with good drainage preferably near the house and easy water access. Southern exposure is best and a windbreak to the north is helpful.

You can use a variety of materials for your cold frame, including cinder blocks for the sides and old repurposed window frames for the top. Here are some links that include detailed instructions and material lists. http://baker.ifas.ufl.edu/Lawn%20&%20Garden/documents/HIGHLIGHTSDEC2015.pdf
http://cceschuyler.org/resources/cold-frames-hot-beds-chemung-county
http://extensionpublications.unl.edu/assets/pdf/g1718.pdf

If you simply cannot let go of your warm season plants yet, you could try building a cloche around them. It’s a bell shaped structure that shelters plants from wind and cold.
https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1627.pdf

Even if you forgot to start your cool season vegetables back in August, think about building a mini greenhouse now. It will be easier to build one when the weather is nice than when there is snow on the ground. You can trust me on this one.

Kelley Rawlsky has an M.S. in horticulture and is the director of Bringing People and Plants Together, an organization dedicated to bringing horticulture education and therapy to the community. For more information: PeopleAndPlantsTogether@gmail.com or follow us on Facebook.

Article originally published in Broomfield Enterprise - Oct. 1, 2017