Bark Mulch vs Decorative Stone for Garden Beds

One feeds the soil and disappears. The other lasts for years and slowly makes the bed harder to plant.

Bark mulch is organic. It suppresses weeds, holds moisture, moderates soil temperature and breaks down over three to five years, adding structure to the soil as it goes. Decorative stone is inert. It does not decompose, does not need topping up, and looks the same in a decade, but it contributes nothing to the soil and it makes replanting genuinely awkward. The choice is less about appearance than about whether the bed is a planting area or a low-maintenance surface.

Depth and the Membrane Question

Both materials need roughly 50 to 75 mm of depth to suppress weeds. Thinner than that and light reaches the soil; thicker than about 100 mm around plant stems and you invite rot. Keep either material pulled back a hand’s width from trunks and stems.

Landscape fabric under stone is usually worthwhile, because it stops the stone working down into the soil and vanishing. Under bark mulch it is usually a mistake: the mulch is supposed to break down into the soil, and a membrane prevents exactly that while also blocking the worms that would incorporate it. Weed seeds land on top of the mulch and root into the decomposed layer regardless, so the fabric buys less than people expect.

Practical Differences Over Time

Bark needs topping up roughly every second year and the colour fades. Stone stays put but collects leaf litter, which decomposes in the gaps and eventually creates a fine seedbed on top of your weed suppressant. Both need maintenance; the difference is that maintaining bark is spreading a fresh layer, while maintaining stone is picking debris out of it.

Summary

Choose bark for planted beds you will keep working, stone for permanent low-maintenance areas and paths. Both want 50 to 75 mm depth. Our Mulch Calculator and Gravel Calculator convert bed area and depth into volume, which is what suppliers sell by.