Can you use shredded gorse for mulch?

Gorse will not make a good mulch. Even if you shred it, the spines will dry out and retain their hardness and will be very spiteful. Gorse splinters are hard to remove and easily infected. The best thing to do, if possible, is to burn the gorse in a garden incinerator or on a bonfire. Then collect the ash and spread it on the ground. It will act as a slow-acting winter feed ready for next year.