Brassica's will include turnips, radishes, and rape seeds to name a few. It will provide a lot of tonage in the form of leaves but also the deer will feast on the bulbs that are produced. Deer will be most attracted to this once the first hard frost has hit. This is when the sugars really become present in the leaves. I would suggest planting them sometime from July 15th to August 15th in the Midwest.
Our brassica mix, Green Beast, is fairly easy to establish as are they all. Once you determined your plot site you need to start by spraying the existing vegetation with a glyphosate to eliminate the competition, unless you are braodcasting into an existing bean plot. After about a week the existing vegetation should be dead and you can then clear it for planting.
There are a few ways to do this. One can either burn the exisitng leaf litter off or you can shred with a mower or weed eater followed by tilling. If you use fire you can just run a drag over the plot before broadcasting to lightly loosen the top soil. If you tilled it pack the soild, broadcast the seed and then pack again. For best results fertilize according to a soil test.
If we can't or elect not to do a soil test we use DeerGro's PlotStart when planting followed by their PlotBoost once it is up and growing. This allows the plant to be most effecient at nutrient uptake bringing in more nutrients allowing them to meet their maximum potential. Brassicas will grow fairly fast so once they are going you should not have to worry about weed control. Given the time of year most weeds are nearing the end of production and brassicas will have no problem outcompeting them.
Now is the time to get those plots in the ground so get out there and start preparing for those late season hunts!