A cold frame is a simple structure used in gardening to protect plants from cold weather. It typically consists of a transparent lid, often made of glass or plastic, that allows sunlight to enter while trapping heat inside. Cold frames can extend the growing season by providing a warmer environment for seedlings and young plants, making them ideal for early spring or late fall gardening. These structures can be built from various materials, including wood or recycled materials, and are often placed directly on the soil. By using a cold frame, gardeners can create a microclimate that helps plants thrive, even when outdoor temperatures are low.