How can I keep grass from growing up through my gravel (with sand base) rock garden without using poisons?

Cierra Gadbaw: More gravel. More sand. If no light shines down to give them energy, then they can't grow.

Cassey Hollinghurst: You can make a poison-free, earth friendly herbicide using salt, vinegar and soap. You'll find different variations of the recipe, like here http://www.therenewableplanet.com/blogs/the_daily_...