Grass and weeds keep growing thru the mulch in my garden. What can I put in it that won't kill the flowers?

I have used the round up, it didn't work.

Grass and weeds keep growing thru the mulch in my garden. What can I put in it that won't kill the flowers?
Roundup only kills the actively growing, green plants.....it doesn't stop the new weeds from germinating.





Landscape fabric is TERRIBLE, and it doesn't stop weeds and grass for very long.





There is a product called PREEN. If used as directed, it safely keeps weeds and grasses from germinating and growing.
Reply:Dogzilla is right on. Pull out what weeds are there, and apply Preen. Don't use plastic. It is terrible stuff, and a b**** to get rid of.
Reply:you should have placed either plastic or a weed mat down before you put the mulch down.
Reply:plastic
Reply:try the rubber mulch i herd its good at keeping weeds down its made from recyled tires