How to Grow Shiso From Seed: Foolproof germination to fuller growth

Shiso is a fast-growing culinary herb widely used in Japanese and Korean dishes and grown as an annual in most USA climates. We’ve grown both green and purple shiso and have some seed-to-harvest tips to share.

For better germination, start shiso seeds indoors 6-8 weeks before your last frost date. Indoor seed starting allows for more control over water, heat, and light. 

• Cold stratify seeds for at least 1 week in the fridge or freezer before planting

• Soak seeds for 24 hours after cold stratification

• Press seeds into soil but don’t cover. Shiso seeds need light to germinate.

• Keep soil warm and moist.

Once seeds germinate, use bottom watering to avoid damping off.

Keep grow lights close to the seedlings so they have adequate light and don’t become leggy and fragile. 

Harden off your seedlings by gradually acclimating them to the outdoor environment.

Shiso is fairly easy to grow and care for. But transplanting can disturb the root system and cause transplant shock. Gently remove the whole seedling and root structure, and plant it at the same soil level it was growing in. 

Shiso is not a heavy feeder and will thrive in fertile soil. Because it’s an herb, avoid high-nitrogen fertilizers, which can cause rapid growth and dilute the essential oils. A balanced fertilizer used once a month should be sufficient.

Damping off is a problem with indoor seedlings. To prevent this, bottom-water once the seeds sprout and use a fan for air circulation.

If you see holes in the leaves, it could be cutworms and caterpillars. We had minor leaf damage early in the season, but the plants still grew vigorously. 

You can start harvesting shiso leaves when the plant is about 6 to 8 inches tall. To create a fuller plant, prune shiso in the same way you would prune basil.

Cut off the tops above a leaf node to encourage branching.

To keep the plant focused on leaf growth and keep it from going to seed, cut off the stalks when flowers form. However, some chefs use the flowers and seeds. 

Yes. With enough light, you can grow shiso indoors.

Our raised beds were the perfect spot to grow shiso. The soil is fertile and stays consistently moist with our drip system. A raised bed also keeps it from spreading in the garden. You can see how large the plants got in our YouTube video. 

• We like the complex flavor of shiso. It’s very aromatic with a bright, minty, citrusy flavor. The purple shiso has a slightly bolder flavor than the green variety.

• We found that shiso doesn’t flower as quickly as herbs like basil and cilantro, so it lasts longer in the season.

• We started seeds indoors and transplanted seedlings outdoors once the weather was warm. 

• You can use shiso in bouquets, and it lasts 3- 5 days in a vase.

• Raw or cooked, you can use shiso to replace basil or mint for a little flavor twist.

Shiso is a uniquely flavored leafy herb that is easy to grow. Use our seed germination tips to get your plants off to a healthy start. If you’re looking to add shiso to your kitchen garden, these heirloom seeds are guaranteed to grow.