I love growing interesting flavors in my garden and bringing them into the kitchen to cook with. That is why I added shiso to my seed list a couple of years ago. I first tried this fragrant herb in a restaurant in Western Canada (where I was also introduced to parsley root). It has a very distinct flavor and is very ornamental. Growing shiso from seed is pretty easy and if you let it go to seed in the fall, well, you won’t need to grow more next year.
How is shiso used in the kitchen?
It’s hard to describe the flavor of shiso. It has a very distinctive taste. I would put it in the same hard-to-define flavor category as cilantro. I find there are hints of citrus and mint and a bit of anise. When I asked Niki (who also grows shiso) to describe the flavor, she answered “minty and basily with a hint of spice. And a little bitter, too.” Some gardeners also taste clove, cinnamon, cumin, and basil.
A member of the mint family (Lamiaceae), different varieties of shiso (Perilla frutescens var. Crispa or Perilla frutescens) are used across a number of cuisines in East and Southeast Asia. Shiso’s botanical name, Perilla, is often used as the common name, depending on the language. It’s also referred to as the beefsteak plant.
Both the leaves and seeds are used. Leaves are used as wraps, to flavor soups, dipped in tempura batter, pickled, sliced into salads, and more.
Shiso leaves are quite spectacular so even though your plan may be to include them in your herb garden, you can add them to an ornamental garden, too. The spade-shaped leaves can span about three inches (7.5 cm) in width and have saw-toothed or serrated edges. Some varieties have a very ruffled surface, while others flatter, with more of a ruffled edge.
Where you can grow shiso
Whether you’re starting from seed or direct sowing, choose an area of the garden that gets full sun to partial shade with well-draining soil. Amend the area well with lots of compost. And be mindful of what is growing around your seedlings. Depending on the variety, the plant height can reach up to three feet tall.
Growing shiso from seed indoors
In seed trays of pre-moistened seedling mix, or soil blocks, lightly sprinkle the seeds on top of the soil. Gently press them into the soil, but don’t bury them too deeply (about quarter inch or 6 cm) as they need light to germinate.
Just like basil, shiso seeds also like a little warmth and humidity to germinate. Cover your seedling tray with a humidity dome or place plastic wrap overtop until the seeds have germinated. Then, remove the cover once there is a sign of seedling growth so the air can circulate around them. A seedling heat mat can also provide warmth to boost germination. It can take anywhere from one to two weeks for seeds to sprout.
Make sure you plant seedlings after the last frost. Harden them off before planting them in the garden or in pots.
Growing shiso by direct sowing
While shiso is a warm weather plant, it is sensitive to cold temperatures. Direct seed shiso after night temperatures have risen above 50°F (10°C). Sow seeds about one inch apart. Cover with about a quarter inch (6 cm) of soil and keep the area moist until plants germinate. Thin seedlings once they’re a few inches tall so plant spacing is about eight inches (20 cm) apart.
Caring for shiso plants
Shiso, like basil, is a heat lover, thriving in the hot sun. It can be drought tolerant, but do water if you see the plants starting to wither in hot temperatures. You can also pinch the plant back to keep the plants shorter and encourage bushy growth. Pinch above a new set of leaves as you would basil, and the plant will send out side shoots.
Shiso is not that afflicted by pests. Apparently aphids can be a problem, but I’ve had aphids on other plants while my shiso plants were unscathed.
Harvesting shiso leaves
Depending on what you’re using them for, harvest leaves when they are young, or wait until they reach their full size. Simply snip a leaf above a node by pinching or with a sharp pair of scissors. Seeds can also be harvested and stored in the pantry or for replanting the following year.
While they’re best used fresh, if you’re not using shiso leaves right away, store them in a paper towel placed in a plastic bag in the fridge for a couple of days.
Letting shiso go to seed
In late summer, shiso develops beautiful flowers, which will eventually turn into seeds. The spring after my first year of growing shiso, I found all these little seedlings in my side garden. I started pulling them out, thinking they were weeds, but then realized they were mini shiso plants. I thinned them out and enjoyed a lovely row of plants for a second season.
Once the cool temperatures of fall arrive, shiso starts to fade, dropping its seeds if the flowers weren’t deadheaded. If you don’t want to be pulling up seedlings the following year, snip the blooms once they start to die, so they don’t form seed heads.
You can also collect those seeds instead of letting them fall in the garden and save them for next year. Be sure to store seed in cool, dry conditions.