There are many different cultivars of brassicas. Heck, the broccoli you eat with your soup is one of them. When it comes to deer food there are only about two or three that really stand out. First, are Purple Top turnips, commonly called forage turnips in many circles. Deer love turnips and will eat the leaves and the tubers. Typically, turnips are recommended for areas with high deer densities where they will eat all the fall foods during the summer. However, they tend to let turnips (and other brassicas) survive until the first hard freeze when a molecular change occurs within the plant to make the leaves more palatable.
The second type of brassica to consider is dwarf Essex rape. This is a plant with big leaves like broccoli and deer will also feed heavily on them after the first hard freeze and into the winter. Finally, a third choice is Tyfon or forage brassica. Cattle growers commonly use this plant because of its high yield and high protein content. And if you get hungry while hunting you make a salad out of it. Bring the Italian dressing in your fanny pack.
There are also many commercial blends of brassicas offered by food plot companies and some of their selections are very highly evolved. I wouldn’t tell you that the standard product you get from the local co-op or from the online seed merchant is just as good as the specialized varieties offered by the food plot companies, but they will definitely work. Deer will come to them and deer will eat them. These planting provide very good nutrition during the fall and winter.
The advantage of brassicas is the fact that deer generally will leave them alone until the onset of colder weather at which time the plot will become very attractive. Brassicas, in general, are also cheaper to plant than typical food plot grain options such as corn and soybeans.