Method. Each material carries a published C:N figure from university extension research (grass ≈ 15:1, leaves ≈ 60:1, cardboard ≈ 350:1…). The tool weights them in proportion to how much microbes can actually chew — a dry cardboard bucket is mostly air and lignin, so its nitrogen contribution is effectively zero compared with the same bucket of grass. The result is an honest working estimate, not lab chemistry.

The moisture test beats any number. Grab a handful and squeeze: it should feel like a wrung-out sponge — a drop or two of water at most. Drip wet? Add browns and turn it. Dusty dry? Add greens or a watering can. Every compost problem passes through that fist sooner or later.

Turn, don’t stir. Flipping the heap every few weeks feeds oxygen to the microbes doing the work; a sealed bin still composts, just slower. Powdery white threads are actinomycetes doing their job — not mould — and shredded hedge trimmings keep airways open in winter heaps.

Never in an open heap: meat, dairy, cooked food (vermin), dog or cat waste (pathogens), glossy magazines, coal ash, diseased plants, weeds that have seeded, or “compostable” cups — those need industrial heat, not a garden bin. Autumn leaves alone make leaf mould in a year: the simplest soil conditioner that exists.

Sources: C:N ranges published by agricultural extension services (e.g. Cornell composting programme); approximation method stated honestly. Last reviewed 2026-09-21.