Brassica juncea 50 days. Harvest at baby leaf stage after 21 days for flatter leaves with serrated margins or full size when they become very frilly. Green Wave has been a favorite American mustard (or tendergreen) for many years. Popular with gardeners for its upright plant habit, it grows to 2 feet and has a dark green, heavily curled leaf. An excellent producer, Green Wave resists bolting, so it can be grown mid-summer. Mild and succulent in all dishes.