How long does it take to compost?

How long does it take to turn your kitchen scraps into black gold?  It will vary based on what you do.  The fastest you could manage is 6 weeks.  2 weeks for the composting, and another 30 days to cool and cure before the compost touches plants.  The longest would be a full year.  What causes such a long range?  There a five main variables.  Here are suggestions if you want to speed things up!

1 - Ratio of carbon to nitrogen (C:N).

You can accelerate composting if you give it the right mix of ingredients.  To create the optimal mix, you want two parts carbon to every one part nitrogen.  Carbon is the "brown" materials, usually dried ingredients.  This can be wood chips, cardboard, fall leaves, and more.  Nitrogen is the "green" materials, usually wet.  These are your live plants, grass clippings, kitchen scraps, chicken poo.  If you think your ratio is slowing you down, add more carbon.  I've heard of carbon:nitrogen rations from 2:1 in The Organic Composting Handbook, to 30:1 in the On-Farm Composting Handbook.

2 - Moisture.

A very wet or very dry compost pile will slow way down.  The bacteria doing the work to break down nutrients like a damp environment, without drowning.  Water every day if you live in a very hot and dry environment, not at all if you have high humidity.  If the pile is wet, increase aeration!

3 - Aeration.

Those bacteria also need oxygen to do their job efficiently.  A few different ways to increase oxygen flow, from most advanced to easiest: add blowers with a fan and tubes into the pile.  Add PVC pipe with air holes through the pile.  Turn the pile - every 3 weeks is recommended.  Add larger pieces of wood chips (3 to 5 inches) to vary particle size, and keep the oxygen tunnels from collapsing.  If the piles starts getting stinky and slimy, it is probably going anaeorbic, and needs aeration (and more carbon).

4 - Chopping.

Bigger things with less surface area take long for the bacteria to break down.  So chop it up smaller!  Instead of putting a whole eggplant or whole apple in the compost, chop to smaller pieces.  If you're composting branches, put them through a chipper first.  Send the plants you want to compost through your lawn mower, or chop it up with gardening shears.  Bacteria and worms seem to like small bites.

5 - Heat.

The compost will process the very fastest if the bacterial are at their favorite temperature.  This is just like making pizza dough or yogurt.  You want to keep it warm, but not so hot that the bacteria will die.  The optimal range is from 95 degrees F to 135 degrees F.  Luckily with compost piles, the bacteria make their own heat, so you don't need to keep it inside or underneath a hot tub.  You just need to keep it from getting too cold or too hot.  It can get too cold if the pile is small.  Bigger than 3 feet by 3 feet will help the bacteria have insulation to generate heat.  Most household have a hard time building a big enough pile to hit high temperatures.  Try offering to compost for your neighbors, or offering to manage the compost pile at your community garden.  Too hot is also a problem. Sometimes the little guys can work so hard that they overheat, and most will die off.  If the temperature spikes, add more water and oxygen.

Well, that sounds like a ton of work!  I have some good news for the low key composter.  The only thing you need to do to make good compost is the C:N ratio.  Everything else is extra credit.  I don't do anything else, and my compost takes a long time.  However, I only use compost in my garden once a year in the Fall!  So I don't see any problem with that.

Do you want compost but don't want to make your own pile?  If you live in NW Aurora, sign up for compost collection service with Wompost!  Check if you are in our service area on our website.

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