In a survival situation, it’s unlikely you’ll be able to “pop down the road” and pickup some mulch. Mulch though, is a very important part of a sustainable garden. If you’ve got enough room, it’s well worth growing these plants just for mulch. There’s high nutrition in the foliage and the supply of it is ongoing – all these plants recover well from a good hacking!
Plant around the edges of your garden beds or on the perimeter of your garden so you can access fresh mulch easily. If you plant them thickly enough, you could create a very effective weed barrier.