Green Mustard Microgreen Seeds

Green Mustard is a fast-growing brassica microgreen with bright green foliage and a fresh peppery mustard flavour. It requires no pre-soaking and can generally be harvested in approximately 8–12 days.

What You Need

• Green Mustard Microgreen Seeds
• A shallow tray with drainage holes
• A solid lower tray for bottom watering
• Coco coir, fine seed-raising mix or another suitable microgreen growing medium
• Clean drinking-quality water
• Fine mist sprayer
• A second tray or suitable blackout 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:

24–28g dry seed per tray

Spread the seed evenly across the growing surface.

Aim for dense, consistent coverage without creating thick piles or heavily overlapping areas.

For more information about adjusting density between different crops, see Microgreen Seeding Density.

Pre-Soak

No pre-soaking required.

Sow Green Mustard seed dry directly onto the prepared growing medium.

The small seed germinates readily without soaking and is considerably easier to distribute evenly while dry.

Step-by-Step Instructions

1. Clean your equipment. Wash and thoroughly rinse the trays, cover and growing tools.
2. Prepare the growing medium. Add approximately 2–3cm of coco coir, fine seed-raising mix or another suitable medium.
3. Moisten before sowing. Water evenly and allow excess water to drain. The medium should be thoroughly damp without being saturated.
4. Measure the seed. Use approximately 24–28g for a standard 25 × 50cm tray.
5. Sow evenly. Broadcast the seed across the growing surface and break up any concentrated patches.
6. Press gently. Ensure good contact between the seed and moist growing medium.
7. Mist lightly. Moisten the seed using clean drinking-quality water without flooding the tray.
8. Cover the tray. Place another tray or suitable blackout cover over the crop.
9. Check daily. Maintain even moisture without keeping the medium saturated.
10. Uncover once established. Remove the cover when most seedlings are rooted and pushing upward.
11. Provide bright light. Move the tray into bright indirect natural light or beneath suitable grow lights.
12. Maintain airflow. Good air movement helps keep the developing canopy healthy.
13. Bottom water once rooted. Switch primarily to watering from below once the root system is established.

Blackout

Keep the tray covered for approximately:

2–3 days

Heavy weighting is unnecessary.

A second tray or light cover can be used to maintain darkness and seed-to-medium contact during early establishment.

Check the crop daily and uncover once the seedlings are well rooted and pushing upward.

For more detail, see Microgreen Blackout Explained.

Germination

Expect germination in approximately:

2–4 days

Green Mustard is generally a fast and vigorous germinator under suitable conditions.

Maintain steady moisture without flooding or saturating the growing medium.

Temperature

Aim for approximately:

18–24°C

Moderate indoor temperatures support fast, compact growth.

Avoid excessive heat combined with stagnant humidity, particularly while the crop remains covered.

Light

After the blackout period:

• provide bright indirect natural light or suitable grow lights;
• rotate the tray if necessary for even growth;
• maintain good airflow;
• avoid excessive heat; and
• avoid keeping the developing foliage continually wet.

The initially pale seedlings should quickly become bright green once exposed to adequate light.

Watering

During early germination, mist gently when necessary to maintain surface moisture.

Once roots are established, bottom watering is preferable.

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

When bottom watering:

• add a shallow amount of water to the lower tray;
• allow the growing medium to absorb moisture;
• check moisture before adding more water;
• avoid permanent standing water;
• minimise repeated wetting of established foliage; and
• maintain good airflow.

Tips for Best Results

• Use approximately 24–28g per 25 × 50cm tray.
• Do not pre-soak.
• Sow evenly.
• Blackout for approximately 2–3 days.
• Expect germination in approximately 2–4 days.
• Maintain approximately 18–24°C.
• Provide bright light after blackout.
• Maintain good airflow.
• Bottom water once roots establish.
• Avoid saturated growing media.
• Harvest young for a milder flavour or allow the first true leaves to develop for stronger mustard character.
• Harvest at approximately 8–12 days.

Harvest Stage

Green Mustard can be harvested at more than one useful stage.

For a younger crop, harvest when:

• cotyledons are fully open;
• shoots are bright green;
• stems remain tender; and
• the crop has developed a fresh peppery flavour.

For a slightly more developed crop, allow the first true leaves to begin appearing.

This generally produces:

• more recognisable mustard foliage;
• stronger flavour; and
• a more textured appearance.

Green & Red Mustard

Green Mustard produces bright green foliage with a fresh peppery flavour.

For a similar growing style with contrasting red-purple colour, see Red Mustard Microgreen Seeds.

Root Hairs vs Mould

Fine white root hairs can sometimes be mistaken for mould.

Healthy root hairs generally:

• grow directly from individual roots;
• appear relatively evenly;
• become more visible as the root zone dries slightly; and
• become less noticeable immediately after watering.

Mould is more likely to:

• spread irregularly between seedlings;
• form web-like patches;
• persist after watering; or
• occur alongside slime, decay or unpleasant odours.

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

Discard crops showing obvious spoilage.

Harvest & Storage

Harvest approximately:

8–12 days from sowing

Green Mustard microgreens are generally ready when:

• cotyledons are fully open;
• the crop is bright green;
• stems are upright and tender;
• shoots are approximately 5–8cm tall;
• the first true leaves are beginning to appear if a larger crop is preferred; and
• the characteristic peppery mustard flavour has developed.

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

Where practical, harvest when the foliage is relatively dry.

For additional guidance, see How to Harvest & Store Microgreens.

Refrigerate promptly in a clean container. If washed before refrigeration, drain and dry thoroughly first.

Growing as Baby Leaf

For baby mustard leaves:

1. Sow substantially less densely than for microgreens.
2. Allow more space between plants.
3. Continue growing beyond the microgreen stage.
4. Provide strong light.
5. Maintain consistent moisture.
6. Harvest once the leaves reach your preferred size.

Growing to Full Maturity

For mature mustard greens:

1. Direct sow or raise seedlings in trays.
2. Transplant or thin established plants to provide adequate spacing.
3. Grow in fertile, well-drained soil.
4. Provide full sun to partial shade.
5. Maintain regular moisture.
6. Harvest younger outside leaves progressively.

Mustard generally performs particularly well during moderate to cooler growing conditions.

Clean Growing / Food Safety

Use a seed lot suitable for edible microgreen production.

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

Maintain:

• appropriate moisture;
• good drainage;
• adequate airflow;
• clean harvesting tools; and
• prompt refrigeration after harvest.

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

Seed Storage

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

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