Is bark mulch beneficial for acid-loving plants

Gardeners often ask whether bark mulch really helps acid-loving plants, or if it merely looks attractive. The answer leans decisively toward benefit. Fresh conifer bark begins slightly acidic, hovering around pH 4.5-5.0, and as it slowly decomposes it maintains a mild sour edge in the topsoil. That suits rhododendrons, camellias and blueberries down to the ground. In heavy rain, the mulch cushions falling water, preventing splash-back that can raise pH with lime particles. It also keeps delicate surface roots cool in summer and insulated through frost, reducing the stress that often pushes pH upward.

Yet the real magic appears beneath the surface. Fungi colonise the decaying bark, weaving fine hyphal threads that liberate iron and manganese, nutrients these shrubs crave but struggle to obtain in alkaline beds. Earthworms tunnel underneath, dragging fragments deeper, gradually forming a self-renewing, humus-rich layer. Because bark chips interlock loosely, air still circulates, discouraging the soggy stagnation that encourages root rot. Top up the layer to a depth of five to eight centimetres every year or two; quality products from AHS LTD make the job straightforward. Within a season the foliage flushes deeper green, blossom improves, and your acid lovers respond with unmistakable vigour every spring.