drainage is very important for WS'ing ... granted there is soil under the gravel.. but so darn compacted I was surprised to see something growing there.. don't even need to fight the grass trying to grow there.. it just doesn't ... when I tried to dig up the plants that started.. the driveway told me to take a hike.. so hard I couldn't even get a shovel in there.. bad news is the poor babies were run over when we had to move the vehicle parked there
