What weed killer can I use in a flower and ground cover flower bed?

depends on the type weed and type groundcover. Weed killers can not tell if you want to kill the plant or the weed.? The killer is just that. Science has created a killer that only kills thin leafed pieces of greenery and science created a killer of broad leafed greenery. Which you're keeping or killing is up to the type of killer you choose.? When working in split decisions of keep or kill nothing science has created comes close to a humans brain working in harmony with human hands. Pull weeds.

Laying down a black plastic or layers of newspapers over the weeds will suffocate them out of the flower bed.

Wendy is correct! Pull the weeds! It is great stress relief and very therapeuti! Make sure you get the roots not just the tops. Then add them to your mulch pile to return them to the earth.

I agree with pulling the weeds out. Once they are gone you can sprinkle PREEN granules on the entire bed and only have to pull a few weeds all summer. I have been doing this for decades. It will not kill existing weeds but stops the germination of new ones. Works best under mulch. Can buy at any garden center and all the big box stores

Armstrong is my go to solution: my strong arms..