I'm going to be planting some seeds in an area where I am sure that a plant marker would disappear, since it is outside the fence. I was thinking of trying to write on some rocks instead. Do any of you know if this kind of paint will hold up over winter, and on a rock? If it won't, can you suggest something else? I figured that if I marked the spot, I'd at least remember where I planted something so that I didn't plant something else there too!