Growing and Saving the Seed Of Mibuna

Latin name Brassica rapa var. japonica, mibuna is a quick-to-mature annual member of the mustard family. The lance-shaped leaves are delicious and make an excellent cut-and-come-again green. This plant is super cold tolerant, though it does not like excessively hot weather. Many successions of this green can be planted, as it matures in 21-40 days from sowing. It is a perfect addition to the market gardener’s repertoire!



An under-the-radar culinary gem, Mibuna is one of the lesser known of the dento yasai, or traditional heirlooms of Japan. Traditionally cultivated in Mibu, Kyoto prefecture.


  • Culinary
  • This mild, tender green is great in salads, lightly stir fried or pickled.




  • Direct sow seeds as soon as soil can be worked in spring or about time of last frost. You will want to stop sowing successions when summer arrives, as heat will impair the plant's growth.
  • Sow seeds 1/4 inch deep.
  • Ideal germination temperature is 65-75 F.
  • Sow seeds 1 inch apart and thin to 4 -6 inches apart in rows 18 inches apart.
  • Seeds germinate in 4-10 days.


  • Plants prefer full sun to part shade.
  • Provide rich, well-drained soil.
  • Consistent watering is best for healthy plants with good flavor.
  • Harvest at 3-6 inches tall for baby greens after just 20 days or allow plants to reach 12-18 inches tall for mature harvest in about 40 days.
  • Harvest multiple times for cut-and- come-again greens.


  • A relatively pest- and disease-free plant.


  • This annual member of the brassica family is insect pollinated. It will not cross with all other members of the large brassica family; it can only cross with other members of the rapa species, which is much smaller.
  • It is best to isolate flowering plants from other members of the rapa species by 800 feet to 1/2 mile or use caging techniques. The most practical choice is to just grow one Brassica rapa for seed saving per season!
  • Allow plants to flower, the green pods to form and then brown and dry, then wait for a dry day and pull up the plants.
  • Dry the pods further in a warm, dry, well-ventilated location.
  • Many will lay the plants on tarps and beat the pods open to free the seeds.
  • Separate seeds from chaff and place seeds in an airtight container.
  • Store in a cool, dark, dry location.