Question
Hi, I'm in south Mississippi. Every year,I broadcast plant large massed beds of zinnias, marigolds, and globe amaranths...and save seeds for the next year.Planting this way allows grass and weeds to come up with the flowers.......sometimes  flowers come up quicker and shade out the grass, sometimes the grass wins. Is there a herbicide that won't harm these flowers? Thanks, rick

Answer
Rick,
There are grass killing herbicides but they do generally harm young plants, which your annuals would be when you use it.  My guess is that the grass seeds/roots are in the soil, yes?  That being the case, and since you live in the south, you might try covering the area with CLEAR plastic NOW.  Leave the plastic on the area until a week or two before you normally scatter the seeds.  If there are enough sunny days from now till then, the heat under the plastic will kill off grass roots and seeds.   

Worth a try if the area isn't too big, or you could do one area at a time, trying a small place first to see if it's successful.

Otherwise you'll just have to look at your area like a wildflower meadow - such meadows are a good percentage grass!  

If you try the plastic, let me know if it works!

all the best,
C.L. Fornari