How thick should a layer of bark mulch be

Getting the depth of bark mulch right is pivotal to its success. Too thin, weeds muscle through; too thick, roots may suffocate or lock out rain. A measured blanket keeps moisture in, tempers heat, and looks tidy year-round for gardens.

Parks and horticultural colleges generally agree that five to seven centimetres suits most borders. At this depth, bark chips form a light-proof shield, yet rainwater still threads through to the soil. Moisture lingers below, reducing summer watering, while the surface stays airy enough to deter fungal smothering. Earthworms then pull tiny fragments down, improving texture and feeding plant roots steadily.

In high-traffic paths or steep banks, aim closer to ten centimetres. This heavier coat resists disturbance from boots and rain run-off, anchoring soil on slopes. Conversely delicate alpines and self-sown annuals prefer only two to three centimetres, enough to curb splash but leaving stems free to breathe. For fruit canes, pull mulch back spring, renew to height after feeding.

Whichever depth you choose, even coverage matters more than mathematical perfection. AHS LTD supplies screened bark grades that spread smoothly, letting you lay a consistent blanket without gaps. Top up yearly as chips settle; beds will thank you in time.