8 to 12 days. Brassica juncea. Wasabi mustard has large green leaves with wavy edges and a fun wasabi-like bite. Easy to grow, this mustard is also cold hardy and vigorous. Don't be mistaken, this is not the actual Japanese wasabi plant, but a great mustard to use fresh in spring rolls, on sandwiches, in stir fry, or traditional mustard-green dishes. Try it at the microgreen stage (7 to 14 days) for a zing on sandwiches or in salads. Note: Lime Streaks Mizuna is a reasonable substitute for Wasabi Mustard.