Cold Frame Growing: Extend Harvest Into Winter

Leafy greens: Spinach, arugula, mache, claytonia
Root crops: Carrots, radishes, turnips
Brassicas: Kale, broccoli raab, tatsoi
Alliums: Scallions, garlic greens

By Sophia Martinez · October 6, 2026

What Is a Cold Frame?

A simple bottomless box with a transparent lid capturing solar heat, creating a microclimate 5-15F warmer than outside. Extends the growing season by 4-8 weeks on each end.

Building Basics

Use untreated lumber (2x10 or 2x12), angled south for maximum sun. The lid can be an old window, polycarbonate panel, or thick clear plastic on a frame.