Moss breaks down slowly in a
home compost bin. After 2 years it may have only shrunk by a quarter
and it may be 3 years or more before there are no longer any
recognisable pieces left.
There are several reasons for this:
When you rake moss out of a lawn or scrape it off the surface of
some earth you do not kill it; moss is much tougher than that. The
species of moss that we are likely to find in our gardens can easily
survive being frozen or being desiccated so putting them into a
compost bin is not going to kill them straight away.
However after being in complete darkness for
several months moss will start to die.
The dead moss then needs to be broken down by specialist bacteria
that can cope with the special aromatics and phenols that moss
species use to defend themselves. Such specialist bacteria will
probably not be present in your compost bin nor will they be
included in activators that you may buy.
However they may be present in the soil
beneath your lawn or in your flower beds, so try to include some
soil with the moss.
These micro organisms that break down moss need a wet
environment to thrive but will probably not be helped by added
nitrogen or other nutrients.
So keep the decomposing moss very wet but
don't buy activator.
It is best to compost moss in a
separate bin where you can
leave it for 3 years or more
keep it wet
keep it dark
Layering the moss with lawn mowings is an easy way to achieve
The bin does not have to be in a sunny place as this will make
little difference to the length of time you will have to wait.
See the very interesting article by Simone Lang in 'Journal of Ecology'
for the full comparison of how bryophytes and lichens decompose in