Coldframes and Hotbeds

Miniature greenhouses for early starts and protection.

Coldframes have no source of heat except the sun.

Hotbeds and coldframes are like miniature greenhouses and they're great for starting plants early or for hardening off plants before setting them in the field or garden.

Face toward south…

When building hotbeds or coldframes, face them toward the south for the best exposure to the light and warmth of the sun. A windbreak on the north side will make the bed easier to heat. A hedge row or a building can serve as a windbreak.

Choose a site that is well drained and not subject to flooding. Mulching around the frame will help to insulate it from the cold.

Hotbeds and coldframes are different.

Coldframes have no source of heat except the sun. Hotbeds may be heated with electricity or decomposing organic matter such as barnyard manure. Electrical resistance wire is a common way of heating hotbeds and some will use an incandescent light bulb.

Hotbeds are used to start plants ahead of normal planting time. This will allow for an earlier harvest. Coldframes protect young, tender plants that are transplanted into the garden from the hotbed so they may produce an earlier harvest.

Coldframes are used to grow out-of-season crops in the midwinter. These include: cabbage, cauliflower, and broccoli. A coldframe should be considerably larger than hotbeds because the plants will spread out more in coldframes and be grown to maturity. Cover both beds with glass or clear polyethylene.

For more information on coldframes and hotbeds contact your local County Extension Office.