A paint brush with Round-up would work well...
I am about to go out and do some Round-up painting and then cover the doomed weeds with mulch.
Linda C

If the grass that is coming up has a little tuft of roots when you pull some, and it is easy to pull, then it may be that one of the mulches carried some seed in it. Simple hand pulling or careful hoeing will take out the problem.

If you bring up a turve when you try pulling check the roots.

If you find it has long wiry roots rather than soft, tender roots, then it is likely that Roundup will have to be used several times. Grasses with 'runner roots' are serious survivors.

If they are wiry, personally I'd fork them all out, shake out as much dirt as possible, and either turn them into liquid manure by keeping them in a bucket of water with a lid on (and a LONG way from the house ;-) ) or burn them because they readily resprout from even a small portion if there's a root joint on it.

Over time, if you do have this sort of grass in your yard, you may find that covering it thickly with untreated sawdust brings it closer to the surface, into a loose and easy to work soil - and it can be more easily removed. Don't use a spade. Chopping it up just increases the problem.

Not killing the grass was the mistake you made. Round up with a paint brush will work, may take several applications as each individual little piece of root that was left in the bed is likely to grow.

Another option, although more work, is to remove the mulch (store in a pile) and perennials (put them in pots) then cover the soil with several layers of newspaper, moisten the newspaper and then cover the newspaper with the mulch. Wait about 6 weeks, the grass will be dead and you can plant the perennials back in through the newspaper and mulch.

Thanks all...for the advice. I know not killing or removing the grass first was a mistake. I would have tried the lasagna method but honestly couldn't wait that long. I think my only option now is to paint it with Round Up so I guess that's how I'll spend my summer.

Thanks again. Jennie

I don't know yet if this is going to work but here's what I'm going to try in an area at my house: Spray paint(orange or white or some other easily seen color)all around the plants coming up I want to keep. Then I am laying down thick cardboard & covering up with mulch.

Kathy: Your idea won't work. If you leave a open space around the plants you want, you will get weeds in that area. If you cover the plants with cardboard and mulch and hope to find the painted areas later, be aware that the cardboard and mulch will kill the plants.

Well, my message disappeared so I'll try this again...Judy, my plan is to use the cardboard & mulch up to where the plants are but where the actual plant(s) are, use that gardener's fabric & cover with mulch. That way the plants can still breathe & come up out of the ground. Anything coming up will be alot easier to get in a small space than a whole bed full of grass and weeds. If this doesn't work, I'll try something else.

If you use land scape fabric, it will silt up...that is the pores of the fabric will fill with soil and water will pool up in it...like a bowl, and when that happens the mulch and fabric will support weed growth.
Very careful Round Up application is the best....and the easiest way to get rid of the weeds..
Linda C

Kathy: If you cover the plants with landscape fabric and mulch you will kill them. It is the lack of sunlight,not lack of air and water that kills them. And they will not be able to grow up through the fabric. If you leave spaces in the fabric you will get weeds.

It would be less work to dig and pot up the plants you want to keep then newspaper/cardboard/mulch the whole bed, wait 6 weeks and then replant your plants.

Does anyone know where I can purchase the RED CLOTH, rather than the Black Cloth, to put down in flower beds and then add the mulch on top of the RED CLOTH. I heard that the sun does not have the elements needed to get the weeds to grow through RED CLOTH? I will deeply appreciate knowing where to buy this...thank you in advance...

Landscape cloth of any colour is not a good idea for flower beds. It works well under decks, pathways and patios where it suppresses weeds. If you use it in a flower bed it will be a nuisance when planting, plus it won't work to suppress weeds. You will need to cut holes in it to plant flower and as soon as you cut a hole in it, weeds will find the hole.

As far as I know, red and black are equally effective at suppressing weeds when used properly. There is a red plastic sheet mulch used for tomatoes; apparently the reflected red light promotes tomato growth.

Here is a link that might be useful: Red plastic mulch