The Composting Process - how organic compost is made

Your everyday garden cuttings can be recycled into a quality organic compost which is full of essential plant nutrients.  

 So how are my garden cutting recycled?

Garden waste such as grass cuttings, leaves and prunings can either be recycled in the garden at home in a compost bin or if you put them in your green council collected bin the chances are they will be recycled by a commercial composting facility such as our facility at Hightown Composting Co Ltd.

The Commercial Way

All garden and botanical waste that arrives at our composting facility are first of all graded, any large woody material (such as large logs) are removed and separately processed into bio-fuel for wood burning power stations.  

The remaining waste is then put through a huge shredder to break it down in to smaller pieces, increasing surface area and allowing the material to breakdown more quickly.  At this point any plastic and metal (such as plant pots and lost garden shears) is removed and recycled separately.







Once the material has been shredded and had any contaminants removed it is then formed into large prism shaped piles known an windrows this is when the composting process really begins.

There are three main phases of composting:

1) The Sanitisation Phase (Weeks 1 &2)
2) The Stabilisation Phase (weeks 3 to 12)
3) The Maturation Phase (weeks 13 to 16)

1) Sanitisation - high temperature must be maintained to kill off weed seed and pathogens.

The material now begins to heat up naturally as it begins to compost, at this point we start to monitor the temperature and moisture content of the composting material everyday.  During this phase the temperature of the compost must be kept over 65 degrees Centigrade for a minimum of 7 consecutive days. The heat is generated by the microbes and Bactria that break the garden waste down, in the first two weeks of composting the temperature can reach an amazing 70 to 80 degrees Centigrade!

We also turn the compost at least two times during this phase because we must maintain aerobic decomposition through out the windrow.

There are three things that are required to compost the material effectively: Moisture, Air (oxygen) and Heat.

The most important of which is Air, without air the Bactria and microbes can not reproduce or live and with out the Bactria breeding and living the temperature will not build up and the material will not be broken down.  This is why we turn the compost every week to reintroduce air into the windrows and to ensure that all the composting material is broken down at the same rate.

2) Stabilisation Phase - a further 10 weeks of actively managed composting, temperature maintained at >55 degrees C.

We continue to monitor the temperature and moisture levels of the composting windrows once a week during this phase.  The compost is also turned at least 6 more times.  After a minimum period of 12 weeks of composting , turning and monitoring, the compost is ready for screening to remove all the uncomposted oversize fraction.

We screen compost to various grades depending on the final use or application of the compost.

3) Maturation 

After screen the compost is stored in stock piles where it matures for a further four weeks before it can be used to fertilise gardens and farmers fields across the country.