We’ve seen gravel mulch, glass mulch, rubber mulch – darn it, we’ve even seen coloured mulch. But just when you thought we’d seen it all, along comes a Kiwi vigneron who wants to try his hand at mulching with mussel shells. Mussel shells?

It makes sense, really! In New Zealand they’re hardly short on a steady supply of these little molluscs yet they’re only valued for their meat. The shells end up as a wastage product.

So is this just a case of reusing a material in another format? Not at all. Apparently the Renwick vineyard is trialling the side benefit of ripening their grapes through the increased light mirrored into the vine’s canopy as the shells fade. It increases the ripening characteristics of the fruit without increasing the levels of sugar.

How could Mussel shell mulch be useful for home gardeners?

It doesn’t necessarily need to be mussel shells, it could be any type of shell that is used (Abalone may be a little too hard, and not easy to source either).

If this vigneron’s trials are successful it could mean a boon for cold climate gardeners who struggle to grow fruit trees because the produce won’t ripen in time. New Zealand’s a good climate to be testing this in and if it proves true the reflective qualities of this mulch will become highly prized.

If you plan to try this mulch in your own home garden you may want to wash them a few times before applying to your fruit trees. The salt that can become encrusted on these shells will eventually break down and will increase the alkalinity of the soil – hardly a bonus for lime-loving fruit trees.

Due to the interlocking shape of these mussel shells they do work well as a mulch. They will restrict the growth of weeds and retain moisture in the soil.

Is there anyone else who’s been using shells as mulch in their gardens and found similar benefits?