Compost is a by-product of the transformation of organic vegetable matter. This natural fertilizer improves soil fertility and reduces CO2 emissions. 

You can practice composting in your garden, yard or on your balcony, or in a community garden, as long as your composter is not visible from the street.

What you need

• An easily accessible, slightly shaded space measuring about 1 m2, sheltered from the wind and placed on flat ground to avoid water buildup.
• A store-bought or homemade domestic composter (some boroughs offer composters at a reduced cost).

For successful composting, make sure to use only vegetable organic matter. Cutting matter into small pieces makes it easier to compost.

Acceptable materials

In the kitchen

• Fruits and vegetables (including the peel)
• Tea bags
• Paper coffee filters
• Coffee grounds
• Eggshells

In the garden

Surface composting is the best option to fertilize and aerate the soil, as well as to increase its organic matter concentration naturally.

• Dead leaves (small amounts)
• Garden debris
• Straw and hay
• Faded blooms
• Dead plants
• Wood chips
• Cut herbs (preferably dried)

Around the house

• Newspaper (in strips)
• Paper towels
• Sawdust
• Houseplants (and their potting soil)

Unacceptable materials

These materials may attract animals, be slow to decompose, be toxic or transmit disease to your plants. 

In the kitchen

• Meat and fish (including bones)
• Dairy products
• Oils and grease
• Avocado and peach pits (and other pits)
• Rhubarb leaves
• Oyster shells or shells from other shellfish

In the garden

• Bolting weeds
• Dead plants or leaves

Around the house

• Cat litter
• Matter treated with pesticides, herbicides or any other chemical product

Basic rules for easier composting

1. Mix types of matter

Alternate between thin layers of dried (or “brown”) matter and moist (or “green”) matter. This will ensure a balanced carbon/nitrogen ratio, proper humidity and optimal porosity for aeration. 

2. Stir to aerate

To oxygenate the microorganisms responsible for composting, regularly stir the organic matter, especially in the beginning. This will ensure uniform decomposition and prevent the compost from drying up or absorbing too much water in certain areas.

3. Check the moisture level

Water the compost if it is too dry and add earth if it is too wet. Too little moisture will dry out organic matter (particularly in the beginning), which will kill the microorganisms and stop the composting process. Too much moisture will cause asphyxia and generate foul odours.

4. Monitor the decomposition and check for odours

Keep a close eye on your compost to detect poor decomposition of matter or the bad smells. The sooner you identify a problem, the easier it will be to take effective action.

5. Keep a reserve of “brown” matter

Keep a supply of “brown” matter, such as dead leaves or wood chips, near your composter. Brown matter will help structure your compost and promote air circulation between the types of matter.