Which part of the world are you in, please?
I guess I would use a trowel to gather up as much equisetum as I could, placing it into a trug or basket to stir myself on that I was collecing so much (otherwise it feels heart breaking). Then I would put down double layers of cardboard, going around the perennials you wish to leave. And finally I’d add the mulch. Where you are (ie. how dry/wet) would decide for me whether to wet the cardboard first or not at all. Good luck! Rome wasn’t built in a day.
