The Compost System

from the Urban Veggie Gardening Workshop #3 with MJ


Written by Mo McCarthy

The successful operation of the MBCG compost system has eliminated our need to purchase commercial soil for the garden.

Thanks to everyone who contributes to making our compost system a success. The compost system has three main components as described below:

Cold Composting

Community contributions of kitchen scraps, and cuttings from the garden beds are put into the 4 round, solid, plastic compost bins with lids. Wood shavings and paper strips are added to these scraps and cuttings. Wood shavings & paper are found in the green wheelie bins also located along the wall. This is known as Cold Composting.

Please note the signs in the compost area indicating GOOD and UNWANTED items.


Hot composting

There are 3 square, wire mesh bins just beyond the cold compost bins. These wire bins are the source of hot composting for the garden.

During the garden working-bees the cold compost bins are emptied into the Hot Compost wire bins. The material from the cold compost bins are layered with sawdust, shredded paper, dried leaves, extra garden cuttings, and water.

Creating these layers of very wet cold compost, wood shavings, shredded paper/leaves is done to break down the contents of the bins and generate high temperatures (approximately 60 degrees C) which eliminates all bacteria and fungus. The end product becomes soil for the garden.

The desired combinations going into the hot compost is 1part nitrogen: 3 parts carbon. Plant based scraps and garden cuttings is the NITROGEN content. Wood shavings, paper, dried leaves, straw, cardboard are CARBON content.

The bins are covered with black plastic and left for 5-7 days and then turned every few days, outside in. The breaking down of the hot compost is dependent on the weather ie, it breaks down faster during higher temperatures.


Finished Compost

The hot compost process will take between 4-6 weeks.  Once the compost has broken down, it is then SIFTED into the square, hessian-lined container.  Items that have not broken down are put back into the bins. The sifted compost is then mixed with soaked coir to aerate and finish decomposing. Approximately 1 block of coir is moistened & added to one sifted hot compost bin. This is finished compost.