I planted Brassica Blend that included the purple top turnip type of beets. The deer won't start coming to them until a good cold snap makes them sweeten up. The first year I planted them, we had a warm fall & the deer weren't interested in them untill season was about 3/4 over and by then they had gone nocturnal, only hitting the plot at night.
At a later time, I attended a seminar put on by wildlife bioligist Dr. Kroll. He reccomends planting other crops instead of the Brassica Blend because the beets/turnips are actually toxic to the deer even though they like them. Now, I plant more sweet peas, beans, clovers, etc instead of the Brassica Blends.