What Are Cold Frames and Hotbeds?
Cold frames and hotbeds are similar structures, with the primary difference being their heat source. Cold frames rely solely on sunlight, while hotbeds include an additional heat source, such as heating cables or manure. Both are constructed with a sash made of glass or plastic and a support frame made of wood, brick, or cement blocks.
Building a Cold Frame
- Materials: Use glass, old windows, or polycarbonate for the sash and wood, brick, or cement blocks for the frame.
- Dimensions: The front should be at least one foot tall, with the back slightly taller (one inch rise per foot).
- Placement: Position the frame with a full southern or southeastern exposure. Use a windbreak, such as straw bales or evergreen hedgerows, on the north or northwest side to provide insulation.
Creating a Hotbed
Hotbeds require additional preparation and materials to provide consistent warmth during colder months. Follow these steps:
- Dig down six inches (or twelve inches for poorly drained soil) and add a layer of gravel for drainage.
- Place burlap over the ground or gravel, then add a four-inch layer of sand.
- Install a heating cable with a thermostat to maintain consistent temperatures.
- Cover the cable with two to three inches of sand and lay hardware cloth over it.
- Place your frame on top and fill it with four to six inches of soil.
Tips for Success
- Insulation: Use burlap bags filled with leaves or install a light bulb for added warmth.
- Temperature Control: Use an automated vent opener to prevent overheating and ensure proper air circulation.
- Watering: Water plants early in the morning to ensure foliage dries before evening.
- Ventilation: Raise sashes opposite the prevailing wind to protect seedlings from windburn.
Conclusion
Cold frames and hotbeds are invaluable tools for any gardener looking to grow food year-round. Whether you’re starting spring vegetables, overwintering plants, or protecting tender perennials, these structures can make all the difference. Get started today and enjoy the benefits of extended gardening seasons!
