How does bark mulch decompose over time

Bark mulch begins its quiet transformation the moment it settles on the soil. Rain softens the outer layers, encouraging fungi and bacteria to creep in, weaving invisible threads that prise lignin and cellulose apart. Earthworms then draw the softened chips below the surface, mixing them with humus. Each season reshuffles the pile: summer warmth speeds microbial banquets, while winter chill slows them to a whisper.

After the first year, you notice a subtle darkening. Larger flakes splinter into ragged shards; resins that once resisted decay leach out under ultraviolet light. By the second or third spring, what looked like woody armour resembles coffee grounds, friable and fragrant. This gradual crumble feeds beds with slow-release nutrients, improving structure without the shock of synthetic fertilisers.

Complete breakdown is seldom tidy. Slivers linger for up to five years, especially beneath shrubs where moisture is patchy. Adding a fresh layer keeps paths neat, but also insulates the living composting factory below. Garden designers at AHS LTD suggest topping up once thickness drops below five centimetres, not for appearance alone but to keep evaporation low and weeds guessing. In the end, what began as bark becomes fertile memory, folded into the soil and gone forever.