How To Make a Hot Bed For Winter Growing

Even in the coldest regions, it is possible to grow food all year round. But in order to do so, you will need to develop some sort of protection for your plants. Greenhouses and polytunnels can go a long way to providing that necessary protection, as can simple row covers and cloches. But sometimes, you may need to provide your plants with a little extra heat to protect them from the worst winter excesses. A hot bed can be a great solution.

What is a Hot Bed?

One way to supply that heat in an eco-friendly and sustainable way is by taking advantage of the heat given off by organic matter as it decomposes. A hot bed is basically a raised bed filled with layers of decomposing straw and manure (or other organic matter), topped by a thinner layer of growing medium (soil/compost) into which plants or seeds can be placed.

What You Will Need To Make a Hot Bed

To make a raised bed that will gently heat a growing area from below, you will require:

  • Materials to make the edges of the raised bed structure and contain the materials inside. You could consider using wood, straw bales, stone, brick, cob/clay or a range of other reclaimed or natural materials.
  • Enough straw/ manure or other organic matter to create a layer within the raised bed that is, once compressed, around 60-90cm deep.
  • A 1:1 mix of soil and compost (ideally home-made & peat free). You will need enough to make a layer that is around 20-30cm deep. (The ratio of heat-producing material to growing medium should be 3:1, as this will help to achieve an ideal temperature of around 24 degrees C.)
  • A cover (glass or plastic) to retain the heat given off from your raised bed and protect your plants. (Alternatively, you could consider creating such a bed within a larger greenhouse or polytunnel structure.)

Making Your Hot Bed

  • First, decide where to position your hot bed, taking into account the conditions in your garden, the patterns of the sun etc..
  • Create the raised bed frame/ edging using your chosen edging materials.
  • Add the straw and manure or other organic materials into the base of the structure.
  • Tread on the mix to compress it and increase its heat-producing capacity.
  • Top this mix with your growing medium and, if direct sowing, rake it to a fine tilth.
  • Cover your hot bed to harness the heat generated by decomposition more effectively.
  • Sow seeds, or place transplants into the hot bed, and water in well.

A hot bed can be a great addition to a year-round garden, and could make it easier for you to keep plants going for longer in autumn, start earlier in spring, or even grow crops all winter long without frost damage. So why not consider making one in your garden?