Sow March - September. Broadcast fairly thickly; dig in at or before flowering. Very fast growing. May help to control wireworms, which are fond of the decomposing plants and eat enough to reach adulthood in a single season, then fly away to find grassland in which to lay their eggs. Treat as a brassica in your rotation as it is susceptible to club root.
Half Hardy annual.
Enough for 45 sq.m.