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Though it is still officially Summer until 22 September 2020, thoughts turn to which crops I can sow and grow in the greenhouse to eat through Autumn and into Winter. I’ve not had that option previously as we only built the greenhouse in March. 

I designed the greenhouse so that some or all of the shelving (either side of the door) can be removed. This gives me an internal floor area of approximately 1.68 square metres (18 square-feet) a reasonable area in which to grow some winter greens to give two adults variation in their diet.

Add in four shelves of just under half-a-square-metre each (max) and that increases to between 3 and 3.5 square metres (37 square feet). The lower shelves will be removed to allow access to the floor area.

But the greenhouse is unheated

  • We’ll use bubble-wrap to line the inside for added insulation.
  • The floor is loose-laid bricks covered with cardboard.
  • Plastic bottles filled with water (and painted half-black/half-white) will act as ‘thermal batteries’, taking in heat during the day and releasing it at night. I’m wondering if white plastic milk bottles will work just as well.
  • We have a steady supply of either type of bottle (a couple of each per week).


Further information about heat sinks and thermal batteries

  1. Mother Earth News
  2. Passive Solar Heating
  3. The Ecologist
  4. Ceres
  5. NBC News
  6. The Independent
  7. The Open University
  8. Science Direct