Shiso seeds germinate best after a wet, cold treatment ("cold stratification") - mid/late May, mix seeds with a small amount of moist sand, peat moss, or paper towel and place in plastic bag and into fridge for 7 days. Then sow seeds outdoors 2" apart. Sow seeds shallowly or cover only lightly because seeds need light to germinate. Keep moist until germination. Or, cold treat the seeds in early April, then in mid April, sow seed inside, shallow depth and expose to light. Germination temp: 70°. Keep well moist until germination. Days to germination: 5-21.
Clip stems anytime after plants are a few inches tall. Remove flowers to encourage more leaves. Leaves are edible raw and cooked. Red Shiso is also gorgeous in cut flower arrangements.
In late summer/early fall, clip stems with seed clusters as seeds develop. Place stems upside down in paper bags to dry.