Shiso

Fresh shiso (Perilla frutescens) runs $8-14 per pound where you can find it - which is mainly Asian grocery stores in larger cities (USDA AMS Specialty Crop Market News, 2023). Outside those markets, you’re not finding it fresh. If you cook Japanese food with any regularity - sushi, tempura dipping, tsukemono pickles, shiso-infused rice vinegar - growing your own is the only reliable supply chain available to most home cooks. It’s an easy annual herb that self-sows so freely you’ll have it indefinitely after the first season.

What it actually is

Shiso is in the mint family (Lamiaceae), native to Southeast Asia and China, and has been cultivated in Japan for over 2,000 years. The two main types used in Japanese cooking are:

Green shiso (P. frutescens var. crispa, also called ao-jiso) - Large, serrated leaves with a complex flavor combining mint, basil, anise, and something uniquely its own. Used fresh as a wrap for sashimi, sliced thin as a garnish, deep-fried as tempura, and blended into condiments. This is what most American cooks encounter in Japanese restaurants.

Red shiso (P. frutescens var. purpurascens, also called akajiso) - Deep purple-red leaves, more intensely flavored, primarily used to color and flavor umeboshi (pickled plums) and beni shoga (pickled ginger). The anthocyanin pigments turn a vivid crimson when acidified, which is why it’s essential to traditional Japanese pickling.

Both types grow identically in the garden. Seed packets often contain both mixed; more often you’ll find them sold separately. The flavor compounds are primarily perillaldehyde - the chemical most responsible for shiso’s distinctive character.

The ROI case

A packet of shiso seed costs $2.99. In the first season, your $2.99 produces enough seed for years of plantings - shiso self-sows so aggressively that the main management task after year one is thinning. At $10/lb average and leaves selling individually at Asian markets for roughly $0.50-$1.00 per 10-leaf bunch, even modest production covers the seed cost in the first harvest. The ongoing cost after year one is effectively zero, because you won’t need to buy seed again.

The fresh market value comparison is stark. A small bunch of green shiso at an Asian grocery - maybe 10-15 leaves, roughly 0.5 oz - costs $2-4. That’s $64-128 per pound equivalent. Your home production cost at maturity is a few minutes of harvesting.

Growing requirements

Shiso germinates slowly and benefits from cold stratification - refrigerate seeds in damp paper towel for 1-2 weeks before sowing to improve germination rates. It’s native to subtropical regions and wants warm soil (above 65°F) before transplanting. Start indoors 4-6 weeks before your last frost date.

Shiso tolerates partial shade better than most herbs - in fact, some shade slows bolting in hot climates and keeps leaves more tender. Full sun is fine in zones 5-7; partial shade is preferable in zones 8 and above.

Soil pH of 5.5-6.5. It’s not particularly demanding about fertility - high nitrogen produces lush growth but dilutes the flavor compounds. Moderate, balanced fertility gives you the best combination of yield and flavor quality.

Space plants 12-18 inches apart. Shiso grows 18-36 inches tall at maturity and becomes bushy. Pinch growing tips when plants are 8-10 inches tall to promote branching and delay flowering. Once it flowers, leaf quality declines quickly.

In USDA zones 7 and warmer, shiso behaves as a short-lived perennial but is best treated as an annual - let it set seed in fall and allow self-sown seedlings to come up the following spring. In zones 5-6, it dies with the first hard frost, but self-sown seeds overwinter in the soil and germinate reliably the following May.

What goes wrong

Bolting is the primary management issue. Shiso is triggered to flower by long daylength (above 14-15 hours) and will bolt in midsummer in northern gardens. Pinching consistently delays this, but eventually all plants will flower. Plan succession sowings 3-4 weeks apart for continuous leaf harvest through the season.

Japanese beetles (Popillia japonica) find shiso’s large leaves attractive and can cause significant skeletonizing damage in the Midwest and Northeast. Hand-pick in the morning when beetles are slow, or apply spinosad. Row cover is effective but impractical once plants are large.

Aphid colonies occasionally establish on new growth. Insecticidal soap handles them quickly.

Fungal leaf spot can occur in humid climates with poor air circulation. Plant at proper spacing and avoid overhead watering.

Harvest and storage

Harvest individual leaves as needed from the bottom of the plant up, or cut stems back by one-third for a larger harvest. Leaves are at peak flavor before the plant flowers - use them promptly at this stage. Store fresh leaves wrapped in a barely-damp paper towel in a container in the refrigerator for up to 5 days. They wilt quickly at room temperature.

Red shiso for pickling is harvested in bulk and processed immediately with salt to extract the pigments and preserve the flavor. Green shiso leaves can be packed in salt in layers (shiso no mi shiozuke) for longer preservation.

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Related crops: Basil, Eggplant, Mint

Related reading: Companion Planting Basics - pairing logic for herbs and vegetables that share similar conditions