Extend Your Growing Season with a Cold Frame


South facing filtered light helps trap heat inside

If you live in a part of the country that gets heavy frosts during the winter or that has a shorter growing season, a cold frame may be just what you need to help extend your growing season, grow veggies during the winter or start seedlings early.

Most gardening manuals recommend starting your seedlings in a greenhouse, but for many people, a greenhouse is not an option due to limited space or the cost of buying one.  If this is the case for you, consider buying or building a cold frame to put in your yard.  They ccan be made in any size, from something as small as a tabletop to something as large as a small greenhouse.  Ideally, a cold frame is built to specifications to sit atop a raised bed, as shown here.  We built this one to extend our growing season into winter and grow salad greens even during the coldest months on the year.  We fortunately live in a region that gets heavy frost but steady, strong sunshine year round.  So, without the need of a heater and only using the energy from the sun, a cold frame was a perfect option for growing cool-weather crops in the winter.

coldframeThe materials we used for this structure were primarily recycled wood from an old deck, a piece of corrugated tin to reflect sun off the back, and we bought a large piece of corrugated translucent plastic for the cover, which hinges open and closed.┬á During the summer months when we don’t need the cold frame, we remove it from the raised bed and store it on the shady side of house, hidden from view.

This cold frame has been great for starting all of our seedlings for the year.  While consistently harvesting salad greens, we also have plenty of room to place several trays of seedlings in as well.  The even, warm temperature and filtered light are similar to the conditions in a greenhouse and are absolutely ideal for starting nearly any kind of plant.

Currently in our cold frame we are growing: mesclun salad mix, rosemary, sugar snap peas, shelling peas, cowpeas, tomatoes, watermelon, pumpkin, beans, onions, morning glory, moonflower, marigold, sunflower, sweet pea, foxglove, daisy, poppy, cosmo, and bee balm.┬á That’s right, we’re growing all of that in just one cold frame.┬á By the time they outgrow this space, it will be warm enough to transplant them outside.