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How to start your HOTBIN in winter


From scientific angle, it is not that much harder to start the HOTBIN in winter than it is in summer.

From a practical standpoint it is harder because;

1) there is less garden waste around to create the minimum 40 cm base layer

2) In winter there is less ‘easy to consume’ waste (e.g. grass) and more ‘slow to consume’ waste (e.g. brown leaves)


There are two options – which route you take depends on what waste you have available and to some extent on your willingness to actively seek out waste to ensure you have the right components. In the end not everyone wants this challenge. We have also noted a more laid back ‘patient’ approach.

Just be aware – we cannot change the laws of physics on heating and rates of cooling. If you do not have the quantity and type of mix to create heat, be patient you are going to have to wait until late spring.

The rule of thumb to getting started and getting the HOTBIN hot is: the more you add the easier it is, the more digestible the waste the faster heat is produced. If the temperature is below 10C (which it is most nights and days after September) you need to also ‘kick start’ the base layer in the HOTBIN with the winter heater (aka a hot water bottle!).



To get going you need a base layer – add lots of waste – at least 40cm (above hatch paneldoor) and more if available. Also ensure the mix has lots of easy to digest waste. As you are unlikely to have cut grass in winter – cheat as follows:

  • Shredded office paper (or chopped up corrugated card) is easy for bacteria to digest. You need lots – think a 1-2 carrier bags full to start and several handfuls each week
  • Add a handful of chicken pellet (poo) or blood bone meal from the garden centre each week. Buy big cheap buckets – and don’t worry – you are merely delaying the application of the fertiliser – all the nutrients will still be in your compost
  • Add a few handsful of autumn leaves on alternative days – but not masses of cold leaves in one go. Leave time for the leaves to heat before adding more cold leaves. Drain rain water off from exceptionally wet leaves
  • Add your kitchen peelings and food waste – but do ensure you also add shredded paper (or cardboard) and bulking agent too


  • Seek out friends with allotments, larger families with waste, even your local grocer – and ask for waste
  • Not enough shredded paper? Most offices produce sacks full of shredded office paper every day. Your company pays to dispose of this – ask for a sack full!

Once going you need to keep the heat up. This will require at least 5-10L of waste a week. It is even more essential in winter that your waste is not ‘too wet’. Always amend your mix with 30g (one large handful) of shredded office paper per one Kg of food waste. That is 2 handfuls of shredded paper per caddy. The easy way to do this is add the paper into the base of the caddy after each empty.

ALWAYS add bulking agent with food waste.


Some people find this ‘amazing’ and they find they have a hot heap in 6-12 hours, others try it a few times, nothing seems to happen and give up.  So here’s a little bit of background on how it works, and the essential thing to get it to work

The science behind the ‘heater’ is:

  • Compost heat is a by product of bacterial activity (i.e. growth)
  • More bacterial activity = more heat
  • Bacteria do not grow much (or produce heat) below 5C and almost not at all at 0C
  • When the waste is cold, only a tiny amount of heat is created by the bacteria and this is quickly lost. (Hence outdoor heaps stay cold/frozen in winter). The HOTBIN’s Insulated walls help retain heat, but there is still not enough heat to raise the temperature of the waste.
  • Why add boiling water? 1 litre of boiling water contains 4200 J energy. The heat moves from the water into the cold waste and is retained within by the insulated walls for a few hours – the HOTBIN acts like a Thermos Flask!
  • The waste heats up around bottle to 30-40C for an hour or so
  • During this short period, bacterial activity increase 8-16 fold. More activity = more heat and the waste moves into a self sustaining increase in temperature
  • There is enough heat to increase the waste temp – i.e. the HOTBON increases, rapidly towards 60C

The technique only works if there is enough easy to digest food waste.

I liken it to a human diet – if you eat a high fibre breakfast you get steady energy all day, but drink coke and sweets and you’ll be on sugar high for a hour! Since the heat from the bottle only last an hour or so, the bacteria need fast food during this hour.

If your bin is full of woody stuff that they find hard to digest, then no new heat is generated. The bottle works  when bacteria have a diet of ‘fast food’ i.e. shredded white paper, food waste, cardboard, soft plant material (grass nettles, comfrey).

All the above might be a little too energetic for some users. Below is an alternative winter method.

Just be aware – we cannot change the laws of physics on heating and rates of cooling. If you do have the quantity and type of mix to create heat, be patient you are going to have to accept ‘warm’ rather than hot composting wait until late spring.


Add waste ‘as it comes’ and let it build up over time. It won’t ‘take-off’ and get into the hot 40-60C range, more likely to move along at 10-30C. But this is still much better than a frozen open heap that is inactive.  As with the fast method, the key in winter is to ensure your waste is not too wet – so add lots of shredded office paper and bulking agent.

Please note the Kick Starter Heater comes with the HOTBIN with all the extras. It is a 2-litre HDPE screw top container that can hold boiling water which you can pop into the top layer of the HOTBIN when it needs a winter boost.

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