Red Shiso Microgreen Seeds

Red Shiso is a slower-growing specialty micro herb with burgundy-red to purple foliage and a complex aromatic flavour. For the most characteristic crop, allow the first serrated true leaves to begin developing before harvest.

What You Need

• Red Shiso Microgreen Seeds
• A shallow tray with drainage holes
• A solid lower tray for bottom watering
• Fine seed-raising mix, coco coir or another suitable fine growing medium
• Clean drinking-quality water
• Fine mist sprayer
• A second tray or suitable germination cover
• Bright natural light or suitable grow lights
• Clean scissors or a sharp harvesting knife

Seed Rate

For a standard 25 × 50cm microgreen tray, use approximately:

12–17g dry seed per tray

Spread the seed evenly and avoid excessive density.

Red Shiso remains in the tray longer than fast-growing microgreens, so sufficient space helps maintain airflow as the true leaves develop.

Pre-Soak

No pre-soaking required.

Sow Red Shiso seed dry.

Pre-soaking is used by some growers, but it is not necessary for successful tray production. Consistent surface moisture after sowing is more important.

Step-by-Step Instructions

1. Clean and thoroughly rinse trays, covers and growing tools.
2. Add approximately 2–3cm of fine seed-raising mix, coco coir or another suitable fine growing medium.
3. Moisten the medium evenly and allow excess water to drain.
4. Spread approximately 12–17g of dry seed evenly across the surface.
5. Press gently to establish good seed-to-medium contact.
6. Keep the seed shallow rather than burying deeply. A very fine layer of vermiculite may be used if preferred.
7. Mist gently with clean drinking-quality water.
8. Cover during early establishment.
9. Check the tray daily and maintain consistent moisture.
10. Uncover once germination is established and seedlings begin pushing upward.
11. Move the crop into bright indirect natural light or beneath suitable grow lights.
12. Maintain good airflow.
13. Bottom water once the root system establishes.
14. Allow the first serrated true leaves to begin developing before harvest.

Covered Establishment

Use approximately:

3–5 days

as a starting point for covered establishment.

Shiso growing methods vary, so use crop development rather than the calendar alone. Remove the cover once germination is established and seedlings are beginning to push upward.

Do not extend darkness merely because some later seeds have not yet emerged.

For more information, see Microgreen Blackout Explained.

Germination

Expect germination in approximately:

3–7 days

Some seedlings may emerge later.

Red Shiso can establish less uniformly than radish, broccoli or mustard, so maintain consistent warmth and moisture rather than attempting to force germination with excessive watering.

Temperature

Aim for approximately:

20–25°C

Red Shiso prefers relatively warm growing conditions.

Cool temperatures can significantly slow germination and early development.

Light & Colour Development

Once uncovered, provide bright indirect natural light or suitable grow lights.

The crop begins with rounded young leaves before developing increasingly distinctive serrated foliage.

Good light after establishment helps encourage:

• burgundy-red to purple pigmentation;
• compact growth;
• healthy true-leaf development; and
• strong visual contrast.

Some natural variation in colour is normal.

Watering

During germination, maintain consistent surface moisture using a fine mist when required.

Avoid flooding or permanently saturating the growing medium.

Once roots establish, bottom watering is preferable.

For more detailed guidance, see How to Water Microgreens: Misting vs Bottom Watering.

Keep the medium evenly moist while minimising repeated wetting of established foliage.

True-Leaf Development

Red Shiso becomes particularly distinctive once its first serrated true leaves begin opening.

At this stage:

• the foliage becomes more recognisably Shiso-like;
• red and purple colouring becomes more prominent;
• the crop gains greater visual texture; and
• the characteristic aromatic flavour becomes more pronounced.

This is generally a more useful culinary harvest stage than very young cotyledons.

Harvest & Storage

Harvest approximately:

16–22 days from sowing

Use the development of the crop as the final guide.

Red Shiso microgreens are generally ready when:

• the foliage has developed good burgundy-red to purple colour;
• the first serrated true leaves are beginning to open;
• stems remain tender;
• shoots are approximately 4–8cm tall; and
• the characteristic aromatic Shiso flavour is well developed.

Cut cleanly just above the growing medium using clean scissors or a sharp harvesting knife.

For more information, see How to Harvest & Store Microgreens.

Refrigerate promptly in a clean container and avoid crushing the delicate foliage.

Culinary Use

Red Shiso microgreens work particularly well with:

• sushi;
• rice bowls;
• noodles;
• seafood;
• eggs;
• salads;
• Japanese and Asian-inspired dishes; and
• plated garnishes.

A relatively small quantity can provide considerable aroma, flavour and colour.

Root Hairs vs Mould

Fine white root hairs can occasionally be mistaken for mould.

Root hairs generally:

• grow directly from individual roots;
• appear relatively evenly; and
• become less noticeable immediately after watering.

Mould is more likely to:

• spread irregularly between seedlings;
• form web-like growth;
• persist after watering; or
• occur alongside soft growth, discolouration or unpleasant smells.

If you are uncertain, see Mould vs Root Hairs on Sprouts & Microgreens.

Discard crops showing obvious signs of spoilage.

Growing Red Shiso to Maturity

Red Shiso can also be grown as a mature annual culinary herb.

For mature plants:

1. Sow shallowly into moist seed-raising mix or prepared soil.
2. Maintain warm, consistent conditions during germination.
3. Avoid burying the seed deeply.
4. Thin or transplant established plants to approximately 25–30cm apart.
5. Grow in fertile, well-drained soil.
6. Provide full sun to partial shade depending on climate.
7. Harvest young aromatic leaves progressively.

Mature plants can grow substantially larger than the microgreen crop and produce repeated leaf harvests throughout the growing season.

Clean Growing / Food Safety

Use clean trays, fresh growing medium, drinking-quality water and clean harvesting equipment.

Maintain controlled moisture, good drainage and adequate airflow.

Discard crops showing visible mould, slime, decay, abnormal discolouration or unpleasant smells.

Seed Storage

Store unused Red Shiso seed sealed in a cool, dry and dark place away from heat, moisture and direct sunlight.

For longer-term storage, refrigeration can help maintain viability. Keep refrigerated seed sealed while it returns to room temperature before opening to reduce condensation.