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Can I start composting in the winter?

Getting your HOTBIN started in autumn and winter.

Yes you can... and here is How:
You can kick-start your HOTBIN to 140° F (60°c) in the autumn and winter by carefully adding boiling water into the plastic bottle (made of HDPE) provided with the HOTBIN.

Please DO NOT attempt to use glass as these can shatter  plastic fizzy drinks bottle made from PET as  they will melt at 212° (100°c), or plastic milk cartons which are thin and will deform with the heat. 

How to use the Kick-Start Water Bottle

Carefully fill your bottle with hot water. Use gloves to twist on the cap and carry the container to your HOTBIN (212°F heat will burn you through plastic very fast). Bury the bottle in the waste, covering it with 4-8 inches of new easy to compost waste, close the HOTBIN lid and leave 4-6 hours before re-checking. 

Downloadable instructions can be found here.

The Science on How and Why the Kick-Start Bottle Works

Once you know this, it is easy to identify when it works and when it doesn't.

  • Heat in a compost heap is produced from bacterial activity (IE. growth).
  • The more bacterial activity = the more heat produced.
  • Bacteria do not grow quickly below 41°F and not at all at 32°F.
  • When the waste is cold, only a tiny amount of heat is created by the bacteria and this is quickly lost to the cold air - this is why cold composting heaps lie almost dormant through winter. 
  • When you add the bottle with hot water into the waste, this heat moves to the colder waste (34 oz. of boiling water contains 4200 Joules of energy as heat).
  • The HOTBIN's insulated walls help retain this heat - just like a thermos flask. The waste around the bottle heats up to 86-104°F for an hour or so.
  • During this short period, bacterial are warm enough to become active. They generate heat, which makes then even more active which quickly heats the waste.
  • BUT bacteria only generate heat when they have food to eat. This last statement makes feeding the composter regularly with waste for continuous composting.

Things to Bear in Mind

  1. This winter kick-starting technique only works if there is enough easy to compost food waste. I.e. If you eat a high fiber breakfast, you get steady energy all day. However, if you drink coke and eat sweets... you will be on sugar high for an hour!
  2. Since the heat from the bottle only last an hour or so, the bacteria need easily compostable food during this hour.
  3. If your bin is full of woody stuff that bacteria find hard to compost, no new heat will be generated.
  4. To sum up - The bottle works when bacteria have a diet of fast food. I.e. shredded white paper and cardboard, food waste and soft plant material (grass nettles, shrub cutting, etc.).
  5. Be aware that in most cases large heat increases will only be seen once the waste level in the HOTBIN reaches the height of the hatch.

Do I Need to Use the Bottle in Summer?

The answer is NO, because you don't need to. You should be able to establish from the above that you do not need to use the bottle in summer. The air temperature will be 68°F (if we are lucky!) and the bacteria will be eating fast enough to develop and generate heat on their own.

Please note: Do not pour boiling water directly into the heap - the water will cool and there will be no energy to dry the extra water (see energy/drying).

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