My guess is yes, it will, esp if it's a stoloniferous one like bermuda. When it does it'll be a bear to pull, too, because it'll have its roots so deep. I think i'd mulch with several layers of wetted newspaper then mulch over that to hide it and keep it from blowing. Basically, you are going to attempt to smother it. You may have to wait till your plants get a bit taller. If they are perennials this may not work- they can't handle their crowns being buried. Most annuals or veggies will be just fine with this treatment as they can form more roots along their stems. You may still get some poking up around your plants that you have to deal with by hand.

I'd start over. That rotting sod and rotting roots with only a few inches of (bagged?) soil on top isn't very healthy for your new plants. It's not even like a farmer planting over a cover crop because they select the cover crop for its nitrogen fixing ability and they till it in before planting.
Even when you till up sod, when you unearth it in the planting process it smells rank, rotten because it hasn't composted properly. Just my opinion based upon experience.
Lasagna gardening is a whole nuther thing done on top of turf. First , you kill off the turf.

I agree, I would start over before things get out of control and becomes a problem to correct. I'm putting in a couple of new raised beds myself this year and made sure the grass was gone, weeds gone before installing. I also tilled and now I'm ready to amend and fill carefully since there will be plantings this year in them. If you can't or don't want to start them over, then I agree with Tamelask and would use newspaper, mulch and perhaps even some landscape fabric to try to keep the weeds down. Living in Charlotte (I used to) I would guess you have fescue and clay soil, just as a matter of personal experience. When I was living there, I reworked all of my landscaping at my house. I put in a nice terra cotta border, dug the beds down about 6 to 8 inches, filled back in with potting soil and had a wonderful garden!! You are on the right track, but I'm a little concerned about the grass. JMO, hope this helps.

Been there, done that, regreted that..... Now we spray roundup or an equivilant to kill the grass and weeds, then lay several layers of newspaper and then the dirt......

Lynne

How about this for a compromise (I realize not ideal):

Section at a time, rake away the dirt and spray roundup on the grass. Then put down newspaper to ensure no stragglers make it. Then, rake the dirt back over each section.

If I do this, how long would it be before I could plant stuff in the bed (i.e. where Roundup would no longer be a danger to new plants).

If you don't want to undo all the work you've already done - another solution is to pile up a deep layer of good soil on top of your raised bed. You can smother the grass and rot out the thatch and roots, but not with 3 inches of soil. It would have to be a foot deep at least and you wouldn't be able to plant anything for a year. Not only is there grass turf under there but plenty of weeds and weed seeds, so everything is going to spring to life in a mad dash to overtake your mound of good soil. Smothering all of them means burying under a deep layer of soil and mulch or turning the soil/mulch like it is a compost pile and let nature break down all that matter. If you don't want to wait then you have to remove what you've done and start over by either killing the grass with chemicals or digging it out.

No matter what you do, weeds are going to show up in this bed anyway, so you'll be doing a lot of work either way. Weeding is a part of gardening. A battle that never ends. But if you start out right you can keep things under control.

read the roundup label- it will say when it's no longer a danger. Regular strength for most plants is ok to replant in about a week but some plants are more sensitive. It will warn you which ones.