VIU Milner Gardens and Woodland

How to start your own compost

by Vancouver Island Master Gardeners Association, Jill Williamson

Question: What is composting?

Composting is a natural process and begins with the thousands of micro-organisms which live naturally in soil.

They feed on a moist heap of organic waste materials, generating considerable heat in the process.
Other groups of "decomposer" organisms go to work as the temperature rises, an ever- changing workforce of bacteria, fungi, and insects. New Brunswick Department of the Environment

Question: How do we build a healthy compost?

“Purposeful biodegradation of organic matter, such as yard and food waste.  The decomposition is performed by micro-organisms, mostly bacteria, but also yeasts and fungi.”

“In low temperature phases a few macro-organisms, such as springtails, ants, nematodes, isopods, and earthworms also contribute to the process, as well as soldier fly, fruit flies and fungus gnats.  There are a wide range of organisms in the decomposer community. “ Wikipedia

Question: Why do we build a healthy compost?

  • Compost benefits the soil by fixing the contents to make it organic matter
  • Allows the growth of healthy bacteria and fungi
  • Nutrients to feed plants
  • Fertilizer for all gardens
  • Uses up kitchen scraps
  • encourages the production of worms

The main benefit of compost is bacteria and fungi!

Beneficial bacteria and fungi act as decomposers and will continue to turn organic matter into food for your plants as they continue to grow and multiply in your soil. 

Insects do not feed on organic matter directly but consume the bacteria and fungi that has been decomposed, whereas worms eat both the organics and bacteria and fungi. 

By applying compost into your soil, the worms in the soil excrete nutrients in absorbable form. 

Fungi provide a few different functions in soil such as nutrient delivery and protection from disease.


  • adds beneficial microbes that provide nutrient delivery services to plants.
  • supports healthy supply of worms.
  • adds nutrient rich organic matter.

There may be millions of bacteria in the soil; to give an idea of their size, you would need 25,000 of them laid end to end on a ruler to make an inch.  They are the most nutritionally diverse of all organisms and can eat nearly anything.  Bacteria utilize carbon as a source of energy to build protein in their bodies to grow and reproduce.  Aerobic decomposers are the most important decomposers. These aerobic decomposers need oxygen levels greater than five percent.  Within days of compiling your compost, the pile will heat up rapidly (withing days), due to the bacteria consuming readily decomposable materials. 

These aerobic bacteria excrete plant nutrients such as nitrogen, phosphorous and magnesium so beneficial to promote healthy growth. 

When oxygen levels fall below the five percent, the aerobes die, and decomposition slows by as much as 90%.  In the process they produce a lot of useless organic acids which are ammonia-like substances that are smelly, contain unavailable nitrogen and can be toxic to plants. 

Fungi are also responsible for breaking down tough debris, enabling bacteria to continue the decomposition process.  They can attack organic residues that are too dry, acidic in nitrogen for bacterial decomposition.  Fungi tend to live only on the outer layer of compost when temperatures are high. 

Some secondary consumers in a compost pile are:

  • flies and fly larvae.
  • Diptera
  • collembola springtail
  • mites
  • earthworms
  • slugs and snails
  • sowbugs
  • centipedes

Where do you place your compost bin?

  • Choose a convenient location so that you can easily use it!
  • Do not locate it just below a tree, as the tree roots may grow up into it!
  • The soil underneath the compost much be well drained.
  • The best place is the middle of your garden

How do you build a compost?

There are many designs of compost bins, but a simple idea uses chicken wire and scrap wood.

4 ft in diameter is a good size as it allows more insulation for more even temperatures throughout the pile. See how to start a compost pile.

Other composters:  pallet composter, wire composter, high-rise composter and tumbler composter or can-do trench composting right in the vegetable garden by digging a trench to add compost then using that area to grow plants and digging new trench beside and continuing the process. Could also start a worm bin to add to your compost when worm supply is high! 

Which method of composting suits you?

  • Wire bin
  • Wooden pallets
  • Worm bin
  • Bokashi
  • Tumbler
  • Electric
  • Keyhole
  • Sheet mulching
  • Trench composting
  • Black plastic bins

Carbon materials                             Nitrogen Materials

Aged hay                                         vegetable trimmings

Oat hay                                            green leaves

Cardboard                                        algae

Dry, shredded leaves                      grass clippings

Sawdust                                            kelp or seaweed

Chopped wood.                               Green shrub clippings

Newspaper                                       tea bags

Cardboard egg cartons                   alfalfa meal

Wrapping paper                               coffee grounds

Paper towels                                    animal manure (herbivores only)

Straw                                                 houseplants

Toilet paper rolls                              weeds

Wood ash                                          flower bouquets

Dried grass                                        human/animal hair

Shredded paper                               aquarium water

100% cotton fabrics

Leave out meat, dairy, and eggs except for the shells; Layer your compost

Add 3 parts brown material (eg. fall leaves, hay, shredded paper, or cardboard)

Add 1-part green material (eg. Grass clippings, weeds, vegetable, and fruit wastes)

Mix or layer materials (once a week turn the pile of compost)

Keep it damp and aerated and wait a few months to see black gold!  Rich soil! (Could be as soon as 18 days)

Kuramoto, Connie; Building Healthy Compost, Nanaimo Transition and Gardens on the Go


For gardening questions in the growing season, contact the Gardening Advice Line.