I would mow it just low enough to barley clip the tip of the tallest plant you planted, which is probably the turnips. Next year you will have mostly alfalfa, clover and chicory come back.The nice thing about clover and chicory is that you can mow it several times a year and mowing it not only helps control weeds, it promotes new growth which really attract the deer. I usualy keep the clover chicory plots all year long and then around august or september Ill lightly disc it up and plant oats and a brassica/turnip mix. As long as you dont go too far with discing the clover comes back really nice which gives deer a great food source in the early spring through summer the next year.