Many plants can go in a cold frame but they fall into four main groups. Cool greens, small roots, hardy herbs, and tender seedlings you want to start early in spring or extend in fall.
The best cold-hardy cold frame plants can shrug off frost and snow without much fuss. You skip warm crops like tomatoes and pick from the deep list of cool-season foods you have grown in cool months before.
I sowed a small bed of mâche in my frame one September on a hunch. That single planting fed my salads from November through March, and I kept clipping the rosettes each week with no replanting needed.
Crops break into two tolerance groups based on how cold they can take in your frame. Knowing these groups helps you pick what to grow when, and stops you from wasting seeds on the wrong plants.
Very hardy crops shrug off temps down to 5 to 15°F (-15 to -9°C) under the lid. These include mâche, spinach, claytonia, minutina, and tough kale that earned its name in cold zones.
Hardy crops handle 22 to 25°F (-6 to -4°C) but suffer below that range. Lettuce, arugula, mizuna, and most Asian greens fit here. Cilantro and parsley work too for fresh winter herbs.
Eliot Coleman is a four-season grower from Maine. He made a name growing tough European crops in cold frames. His top picks of mâche, claytonia, and minutina show up in many winter garden books.
Winter vegetables cold frame lists also include roots like carrots, beets, turnips, and radish. Sow these in late August for fall pulls and storage right in the warm soil under the lid through winter.
I tested winter carrots one year and pulled sweet, crisp roots in February that beat any store version. The cold actually pushes more sugar into the carrot, which makes them taste better than summer-grown roots.
Hardy herbs like rosemary, bay, sage, and parsley overwinter well in pots inside the frame. They die in open ground in cold zones but live for years tucked under a frame lid that holds 20°F (11°C) warmer at peak sun hours.
Spring seedlings round out the best cold frame crops for the early months. Start brassicas, onions, leeks, and lettuce in flats inside, then move them to the frame in March to harden off for the open garden.
When I first picked seeds, I bought any old packet from the rack at my local store. My plants bolted and died fast, so I learned to seek out winter-bred types from cold-climate seed firms.
Order proven winter types for the best results year after year. Look for Tyee spinach, Winterbor kale, and Winter Density lettuce from a cold-climate seed company near you. Your harvest will reward you for the small extra step.
I found my favorite seed firm by asking three local frame growers what they used. Each gave me the same answer, so you can save time by trusting word of mouth in your area.
Mix and match these plants can go in a cold frame picks across the four groups. Your box will stay full year-round with fresh food at your fingertips no matter what your weather throws your way.
Read the full article: Cold Frame Gardening: Complete Guide
