Most of the sweet William died that winter. While the planter was sitting in the garden, some shiso seeds must have fallen into it, and produced a lot of “volunteer” shiso plants. I thought the green and purple herbs were pretty so I let them grow. The shiso died at the end of last summer, so I cut off the stalks before I moved the planter to my office for the winter.
I wasn’t too surprised to see shiso seedlings again in my planter recently; like many herbs, shiso grows like a weed. But then, the tiny herbs started blooming! The plants are only two to four inches (5 to 10 cm) tall. When they grow outside, even in the same relatively small window planter, shiso plants usually reach two feet (60 cm) tall or more before they bloom.
Green shiso is known as ao-shiso (青紫蘇, literally “blue shiso”) in Japan. The leaves are used in cooking; for example, chopped, fresh leaves may be added to cold noodles. The flavor is difficult to describe but delicious.
The leaves of aka-shiso (赤紫蘇, “red shiso”) appear purple to me. They are typically used as a dye for foods such as umeboshi (pickled plums) rather than as a flavoring agent.