Filbert trees are the source of the hazelnut. The nuts are prized for cooking, baking and eating out of hand. Once shelled, the hulls or husks are left behind as garbage. Mulches are organic or inorganic covers for soil. Hazelnut shells provide an organic biodegradable mulch to protect topsoil and prevent weeds. Hazelnut shells do not immediately absorb water, which means pathways and areas covered with the mulch will remain solid and become less muddy.
It may seem obvious, but a nut mulch can be extremely attractive to squirrels and other animals. Any organism that enjoys nuts will find small bits of hazelnut meat in the husks that failed to be removed by the automatic shelling process. Squirrels will make holes in the mulch and soil and other less adorable rodents will dig and nibble their way over the mulched area. Birds will also be evident until the nut meats are all eaten and will leave their characteristic white wash marks on the mulch and other nearby areas.
Hazelnut shells are only available as a mulch in areas that grow filbert trees or hazelnuts. As a newly popular mulch option, hazelnut shell mulch is still expensive compared to bark mulches. As of 2011, yard of nut mulch costs $37, while a yard of bark mulch is about $32. Hazelnut mulch is only on the market in areas that have commercial filbert orchards. It is not shipped to most other areas and can be difficult to find. The cost goes up when the shells are bagged, which is the manner of sale in non-production states.
The fact that hazelnut shell mulch is long lasting might seem to be a good thing, but it is a problem if you don't want the mulch anymore. Hazelnut shells will fade over time, but the shells will persist in soil for years. The edges of the shells are sharp and do not make a desirable texture for foot traffic. In fact, the shells will continue to crack and break if you are walking on them, compounding the painful situation.