I planted raab at the end of August and thanks to a warm, sunny fall am getting the first heads forming now in early October. I haven't tried to winter it over but usually I stick to overwintering plants that you harvest leaves for cut and come-again for since heading plants seem to get more easily stressed by the deep cold of winter.

Brocolli raab grows fast so is great for an early spring planting, protected with season-extending devices. I've never had enough raab to freeze but would guess you could blanch and freeze like regular broccoli. Seems a shame to freeze something that's so easy to grow in the cool temps and that is so delicious fresh!