The Cold Frame Single is in fact a miniature greenhouse that will allow you to get a jump on the growing season. It is 21" x 41" and has an aluminum framework. Grow in your containers or directly in the soil. The clear, adjustable polycarbonate cover will provide maximum light and just the right amount of ventilation. Insulated polycarbonate sidewalls will protect your tender seedlings during cool nights. It comes with four ground spikes.