Crabgrass in Star Jasmine planter boxes!?

I've got separated star-jasmine plants surrounded by mulch, and the mulch has crab grass growing around the edges. I ripped as much of the crab grass as I could out but I know it can come back really easily. Can anybody reccomend a spray that will kill the crabgrass but wont kill my star jasmine? The star jasmine are still very young.