How do you grow shiso microgreens? Sow about 11.5 grams of shiso seed per 10×20 tray on a moist mix or grow mat, press it in, and keep it covered near 75°F (24°C) until it sprouts. Then grow it under light with bottom watering, and cut at the first true leaf. Johnny’s Selected Seeds reports an average of 16 days for its ‘Britton’ shiso.
Key takeaway: Shiso microgreens (Perilla frutescens) are a slow but striking herb micro with ruffled green-and-purple leaves. Johnny’s Selected Seeds sells ‘Britton’ shiso microgreens in its 16–25 day group, and NC State Extension notes that perilla, also called beefsteak plant, is an edible member of the mint family (Lamiaceae) whose leaves are used as a salad herb.
| Factor | Guideline | Source |
|---|---|---|
| Seeding rate for shiso microgreens | 11.5 g per tray (about 2.5 flats per oz) | Johnny’s Selected Seeds |
| Days to harvest | About 16 days to first true leaf | Johnny’s Selected Seeds |
| Seed count | About 135,400 seeds per lb | Johnny’s Selected Seeds |
| Germination temperature | 75°F (24°C), then 60°F (16°C) root zone | Johnny’s Selected Seeds |
| Harvest height | 1/2–2 in (1–5 cm) | Johnny’s Selected Seeds |
| Outdoor caution | Invasive in NC, VA, WV, TN and KY | NC State Extension |
What Do Shiso Microgreens Taste Like?
Herbal, minty and slightly licorice-like. Johnny’s describes ‘Britton’ shiso microgreens as ruffled, two-toned leaves, silvery green with purple undersides, with a licorice flavor, and its comparison chart lists the taste as clove and mint. Johnny’s suggests micro shiso to garnish desserts or to balance the heat in spicy Thai dishes.
- Look: ruffled leaves, green on top and purple beneath.
- Taste: clove, mint and subtle licorice.
- Use: sushi, desserts, Thai dishes and cocktails.
How Much Seed Do Shiso Microgreens Need?
About 11.5 grams per tray. Based on its yield trial, in which each 1020 flat was weighed before and after seeding, Johnny’s recommends 11.5 g of ‘Britton’ shiso per tray, or roughly 2.5 flats per ounce of seed, and lists about 135,400 seeds per pound. Penn State Extension says seed density commonly ranges from 2 to 12 seeds per square inch (1 to 6 per cm²).
Our microgreen seed density guide shows how to scale that to other trays.
How Do You Grow Shiso Microgreens Step by Step?
Use Johnny’s standard microgreen routine. Broadcast seed on moist potting mix or another soilless medium in shallow trays, press it firmly into the surface, and cover lightly with mix, vermiculite or a humidity dome. Johnny’s says seeds can germinate on heat mats, in germination chambers or on benches, and its chart notes that all its microgreens suit hydroponic growing.
- Fill a 1020 tray with moist mix or a grow mat.
- Weigh about 11.5 g of untreated shiso seed.
- Scatter evenly and press seed into the surface.
- Cover lightly or stack a blackout lid on top.
- Keep the root zone near 75°F (24°C) until it sprouts.
- Uncover and move under a grow light.
- Bottom water to keep moisture even for about 2–3 weeks.
What Light and Temperature Do Shiso Microgreens Need?
Warm to sprout, then bright light. Johnny’s recommends 75°F (24°C) soil until germination, then 60°F (16°C), with air at 65–75°F (18–24°C); above 75°F (24°C), disease risk rises and germination can suffer. Oregon State University Extension suggests a lamp as close as 3 inches (7.5 cm) above the plants for about 15 hours a day, noting that dim light makes greens lean and stretch.
- Blackout: about 3–4 days, or until sprouted.
- Light: about 15 hours a day.
- Airflow: fans help over the longer crop time.
How Do You Water and Feed Shiso Microgreens?
Bottom water and keep the medium evenly moist. Johnny’s recommends bottom watering or misting to avoid splashing mix on seedlings and warns not to let the medium dry out. It says a dilute fertilizer solution suits media with no nutrients and slow-growing species that might run out of fertility before harvest, which can include shiso. Our microgreens bottom watering guide shows the setup.
When Do You Harvest Shiso Microgreens?
About 16 days after sowing. Johnny’s trial averaged 16 days to maturity when ‘Britton’ shiso was harvested at the first true leaf rather than the cotyledon stage. Harvest at 1/2–2 inches (1–5 cm) tall with scissors or a sharp knife, handling the greens as little as possible. Johnny’s says shelf life is 5 to 10 days under proper storage.
See how to harvest microgreens for clean cutting tips.
Why Are My Shiso Microgreens Moldy?
Long crops in dense, wet trays invite disease. Johnny’s says densely planted microgreens are prone to damping-off with poor air circulation and saturated media, and recommends horizontal airflow fans, clean media and water, and the right seeding density. Oregon State University Extension adds that seeds and seedlings can rot or mold if the medium is too wet and cold. See our microgreens mold guide.
Should You Grow Green or Purple Shiso Microgreens?
Either works; pick for color and flavor. NC State Extension lists ‘Purple Shiso’ with purple leaves under var. crispa and says shiso types have more deeply toothed leaves and a different flavor. It explains that the common name beefsteak plant comes from purple-red leaves that can resemble raw meat. Johnny’s ‘Britton’ gives you both colors: green tops with purple undersides.
Is Shiso Invasive If You Grow It Outdoors?
It can be. NC State Extension says perilla is listed as invasive in Virginia, West Virginia, Tennessee and Kentucky and is classified as invasive by the NC Invasive Plant Council. It self-seeds prolifically, so pinch off flowers before they set seed if you grow plants on. NC State also notes perilla can be toxic to cattle. Microgreens are cut long before flowering.
FAQ About Shiso Microgreens
How long do shiso microgreens take?
About 16 days to first true leaf, per Johnny’s trial.
How much shiso seed per tray?
About 11.5 g per 1020 tray.
What do shiso microgreens taste like?
Clove, mint and subtle licorice.
Can shiso microgreens grow hydroponically?
Yes, on grow mats with bottom watering.
Is shiso the same as perilla?
Yes; shiso is Perilla frutescens, var. crispa.
How tall should they be at harvest?
About 1/2–2 inches (1–5 cm).
Sources
- Johnny’s Selected Seeds — Shiso, Britton Microgreen Seed
- NC State Extension — Perilla frutescens
- Penn State Extension — The ABCs of Microgreens
- Oregon State University Extension — Microgreens
- Johnny’s Selected Seeds — Microgreens Comparison Chart
- Photo credits (Wikimedia Commons, edited with titles): Young Perilla by sarang (Public domain); Perilla frutescens var. crispa 001 by H. Zell (CC BY-SA 3.0); Perilla frutescens var. crispa Akashiso (1427846725) by Henry Heatly from Chicago, United States of America (CC BY-SA 2.0)