I rather rashly broke up a nasty concrete patch in our garden, and we now have a horrible rubbly mess instead. I was thinking of filling it with gravel or bark chippings but wondered about planting it up. If I fill it with compost, what could I plant that is low-growing, dense and doesn't need deep, good quality soil? It?s an area that gets walked on a lot so I would need something that completely covers the ground. Any suggestions?