flea beetle isn't normally a problem - except where you eat the leaves - like with Pak Choi......... :(
keep hoeing round the plants - that may get rid of some. Also, if you try cards smeared with grease on the ground by the plants -tap the plants and the beetles jump off and stick to the cards...never tried it
you may find as the season goes on, the plants grow more quickly than the beetles can eat holes in them