Try Preen or Preen & Green. Preen is a weed preventer & Preen & Green
is a weed preventer plus fertilizer. We use it with great results. Get
rid of all existing weeds and then work it into the soil according to
directions. It is a pre-emergence so won't hurt any existing weeds (or
plants) but prevents others from germinating and coming up.

Marv-Montezuma, IA
http://community.webshots.com/user/vmwood