How do I build a cold frame? When I was a kid, our family worked a huge garden with my grandparents. Part of growing a successful garden, my grandmother used to say, is getting a good start.

In the cold country of the Northern Plains, snow might linger on the ground into late April, and it isn’t that uncommon to receive snowfall in early May — as most Nebraska farmers know quite well. Getting a garden started under those conditions can be challenging. That’s where a cold frame comes in handy.

We built one into the ground near our garden — simply a bottomless box made of old wooden planks, using recycled storm windows as the “roof” of the box to capture the sunlight. Solar energy coming through the old windows, or a transparent “roof” of some kind, warms early-planted seeds and protects those early vegetables from the wind and cold temperatures.

Extend the season

As another way to extend the gardening season, cold frames offer gardeners the ability to start their own garden plants from seed in the spring, or to extend the growing season well past the first hard freeze in the fall. Many expert gardeners suggest seeding crops such as radishes or lettuce, and perhaps salad greens like kale and spinach in a cold frame.

Building a cold frame is not difficult. You can purchase prefabricated versions if you like, but the frame of the box can be made at home using old boards, plastic, or even concrete blocks or bricks leftover from a landscaping project. Be sure to set up the cold frame structure on a site with good soil and sunshine.

Recycled materials

For building materials, you’ll want to avoid boards that have been treated with creosote, for instance. You can top the box with old windows, as we did in my youth, or you can use a frame covered with clear plastic — keeping in mind that thicker materials will keep the cold frame warmer and will be less subject to damage from storms, wind and wild critters that may roam about.

If you use windows or other recycled materials, you can hinge the “roof top” if you like, or simply slide them off to the side when you are working your early garden. It doesn’t have to look pretty to be effective. Wooden-box cold frames can be painted to protect them from the elements and deterioration over time.

Please email your farmstead landscaping, turf, forestry or gardening questions to [email protected].