Grow outdoors from March-April or August-September or in greenhouses in late winter February-March or September. Direct drill rocket seeds in rows 15cm apart or sow in seed trays or modules. To extend the outdoor season on either end, cover rocket with horticultural fleece to keep the cold at bay, and you could be cropping right through to first frosts.
Rocket originates in the Mediterranean area. The Romans grew it for both its leaves and the seed which was used to flavour oils. In the UK it’s known to be used in salads since Elizabethan times. But only recently it’s enjoyed an enormous growth in consumption and appreciation. All of the plant including the leaves, flowers and seeds are edible.