Grass taking over wildflowers

Last fall, hoping to attract more pollinators, I removed a section of lawn and planted a mix of annual and perennial wildflowers. It's only a small area (~80 sq ft), but has been a wonderful bee magnet, bringing in several species that I had never seen in my yard. Those bees seem to be a boon to my fruit and vegetables, and I'd like to keep the bees coming back. Unfortunately grass is already taking over the wildflowers. The grass is moving in even though the flowers are thick and completely shade the soil.  I'm wondering if there's something easy I can do to slow the grass without having to dig it all up and start over. I'm in the city and probably shouldn't burn. I'm afraid mowing would only speed the grass' dominance, but maybe there is a time of year when this would not be the case. Pulling the grass is tedious and tramples the desirable plants. I'm in a hot, humid area with mild winters, so the grass grows year round. Any advice?

If the wanted flowers are tall enough you can lay down cardboard and cover with bark chips.

If you're talking about growing from seed, that's a toughie though.

Jake, I wish I had something encouraging to recommend, but it seems that grasses are every gardener's worst enemy. My best solution has been to go into the flower bed and cut back the grasses with garden scissors.  Then I work a thick layer of wood chips in between the flower plants. Not ideal, because the grasses come back, but it does seem to slow them a bit. It's work, but I always considered that the pollinators are worth it.

I think wildflowers are naturally happiest when mixed with grasses. In my small back yard I've let the grass go long and planted some purchased wildflowers. I had to chop and drop a couple times a year for a couple years, but now they can fend for themselves against the grass. I think this un-managed state is beautiful but it probably wouldn't fly in the front yard where the whole neighborhood can see.

I would dig bAck the grass and cut a deep trench around the bed. Then use an edging tool to keep that grass back.

Thanks everyone for the suggestions. I'll try the combination of trimming, mulching, and trenching. That should slow the grass enough to keep the flowers competitive. This is in my backyard, so the HOA cops can't see it and I don't mind there being some grass mixed in. I just don't want the grass to dominate. Thanks again!