It is autumn in Castle Rock, Colorado. The days are still sunny and warm but the evenings are already dipping into the chilly low 40’s.

We have a seedling crop in our garden beds and will need to extend our growing season as long as possible. Due to a long vacation, we were a month behind in planting our second crop of lettuce and spinach. We need to retain the heat in the soil to promote plant growth.

I used pieces of salvaged plexiglass to construct a temporary cold frame around a couple of our raised garden beds.

The plexiglass radiates the added warmth from the sun onto the plants while heating up the soil.

What we are noticing is faster plant growth.  In less than two weeks our lettuce seedlings have developed into ready to be thinned salad.

Should we encounter a threat of frost we can simply toss a blanket and tarp over the cold-framed garden beds. We look forward to consuming fresh salad greens well into November this year.