I have commercial weed killer from a buddy who works for a fertilizing company.I've had good luck with Preen. But you've got to put it down before the weeds start (obviously).
Preen ~ Garden Weed Killer and Weed Preventers, Lawn & Grass Weed Control and Prevention
Weed control products for flower and landscape beds, lawns and vegetable gardens.www.preen.com
I was talking about something like below.
Vigoro 4 ft. x 200 ft. Medium Duty Point Bond Weed Barrier Landscape Fabric NMV04200B - The Home Depot
Keep weeds away from your gardens and landscapes with this 4 ft. x 200 ft. weed barrier landscape fabric. Designed with lightweight material that is free from chemicals, this medium-duty barrier uses specific techno-logy to block weeds. It promotes plant growth by keeping the soil cool and...
www.homedepot.com