Coco & Coir
Taking the completely biodegradable husk from coconuts, Coco & Coir have masterfully used this natural byproduct to create expanding compost. Its peat free and eco-friendly, and the cost on the environment is far smaller than regular bags of compost (partly due to its stack-able shape and light weight). The largest size can fit in your shopping bag and expands to 75L, enough to fill a wheelbarrow. Simply add warm water to the dry brick, and wait for it to grow. You can seal it in a bin bag to use again and again, just use as you would a regular compost sack.