Composting is one of the most straightforward ways to reduce kitchen waste and improve backyard soil in a single process. In a Canadian context — where winters are long and summers are compressed — the timing and method choices matter more than they might in warmer climates. This guide covers the fundamentals without padding.
Choosing a Composting Method
There is no single correct system. The choice depends on available space, the volume of material being added weekly, and how quickly finished compost is needed.
Cold Composting
The simplest approach: pile organic material in a designated spot and leave it to break down over 12–24 months. No turning, no temperature monitoring. The pile will decompose on its own through fungal and microbial activity. This suits gardeners who generate small amounts of material and are not in a rush. The downside is that weed seeds and pathogens may survive in areas of the pile that never heat up.
Hot Composting
A managed process that requires maintaining the pile at 55–65°C (130–150°F) through regular turning and correct material ratios. At this temperature range, most weed seeds and pathogens are killed within a few days. Hot composting can produce finished material in as little as 6–8 weeks when done correctly. The pile needs to be at least 1 cubic metre to generate and hold heat. This approach works well through Canadian summers when daytime temperatures support biological activity.
Vermicomposting
Red wiggler worms (Eisenia fetida) process kitchen scraps into castings that are exceptionally high in plant-available nutrients. A worm bin can be kept indoors year-round, making it the only viable active composting method through a Canadian winter without a heated outdoor structure. A standard household bin (roughly 60 × 40 × 30 cm) can handle 1–2 kg of food scraps per week. Worm castings are most effectively used as a soil amendment or diluted into liquid feed, not as a bulk growing medium.
Bokashi
An anaerobic fermentation method using inoculated bran. Food scraps — including meat and dairy, which are excluded from most outdoor compost piles — are fermented in a sealed bucket over 2–4 weeks, producing a pre-compost material that must then be buried in soil or added to a conventional compost pile to complete decomposition. Useful for households that want to divert all food waste, not just plant-based scraps.
Siting a Compost Bin
Outdoor compost bins perform best when placed on bare soil rather than paved or decked surfaces. This allows worms and soil microbes to move in from below and improves drainage. A partially shaded location reduces moisture loss in summer without slowing decomposition significantly. Keep the bin accessible from the kitchen path — if it requires a trudge through wet grass to reach, it tends to get neglected in November.
Municipal bylaws in most Canadian cities require compost bins to be at least 1 metre from a property line. Check your local regulations before placing a permanent structure.
The Carbon-to-Nitrogen Ratio
Compost microbes need a balance of carbon-rich "browns" and nitrogen-rich "greens" to work efficiently. The ideal ratio by weight is roughly 25–30 parts carbon to 1 part nitrogen, but in practice this translates to adding roughly equal volumes of browns and greens and adjusting based on smell and moisture.
Browns (carbon-rich)
- Dry fallen leaves
- Cardboard torn into pieces (no glossy coatings)
- Straw
- Wood chips (in moderation — they break down slowly)
- Paper egg cartons
Greens (nitrogen-rich)
- Vegetable and fruit scraps
- Coffee grounds and paper filters
- Fresh grass clippings
- Garden trimmings (non-diseased)
- Tea bags without plastic mesh
A pile that smells of ammonia has too many greens. Add browns. A pile that has stopped generating warmth and is dry needs water and greens.
Managing Compost Through Canadian Seasons
Spring and Summer
The warmest months (June through August in most of Canada) support the fastest decomposition. Turn the pile every 7–14 days to introduce oxygen. Monitor moisture — the pile should feel like a wrung-out sponge. If it dries out in a hot week, add water. Leaves collected the previous fall are excellent carbon material to layer in with summer kitchen scraps.
Autumn
Leaf fall provides a large supply of carbon material. Shred leaves before adding them to prevent matting — whole leaves compact into impermeable layers that slow decomposition. A lawn mower passed over a pile of leaves reduces their volume by roughly two-thirds and increases surface area for microbial contact. Continue adding kitchen scraps through October and into November in most regions.
Winter
Microbial activity slows dramatically below 10°C and largely stops in a frozen pile. This is normal. Continue adding kitchen scraps to the bin through winter — they will sit inert until spring, then begin decomposing as temperatures rise. Insulating the bin with cardboard or a burlap cover can extend the active season by a few weeks in shoulder months. In regions with consistent temperatures below -20°C (northern Ontario, prairie provinces), the bin will freeze solid by December and will not process material until May.
What Not to Add
- Meat, fish, and bones — attract wildlife; include in Bokashi systems instead
- Dairy products — same reason
- Diseased plant material — pathogens may survive in cold or poorly managed piles
- Invasive plants that spread by rhizome (e.g., goutweed) — roots can survive composting
- Pet waste — can contain pathogens not eliminated at typical compost temperatures
- Treated wood or sawdust from pressure-treated lumber
- Coated or heavily inked paper
Knowing When Compost Is Ready
Finished compost is dark brown to black, has a pleasant earthy smell, and no longer contains recognisable food or plant material. The temperature of the pile will have dropped to ambient — no longer generating internal heat. A simple test: fill a sealed bag with a small sample and leave it in a warm room for a week. If it still smells earthy rather than putrid, it is ready. If you are using it as a seed-starting mix, pass it through a coarse sieve (10–12 mm) to remove large particles.
Compost applied to garden beds in early spring, before planting, improves soil structure and adds slow-release nutrients. A 5–8 cm layer worked into the top 15 cm of soil is a reasonable application rate for established beds. For new raised beds, finished compost is typically used as 20–30% of the total soil volume, mixed with topsoil and a drainage amendment such as perlite or coarse sand.
