Zone 5 · Microgreens Growing Guide
One of the most nutritionally dense microgreens — contains up to 100× the sulforaphane of mature broccoli. Mild, slightly earthy flavour with a satisfying crunch.
Indoor tray crop — no outdoor space or frost dates needed. Ready to harvest in 7–14 days on a windowsill or under a grow light.
Indoor year-round. Use untreated broccoli seed only.
Here is what to expect at each stage — and what to do when you get there.
Sow densely and evenly. Mist thoroughly, cover with a blackout lid or second tray, and press down firmly to ensure seed
Leave covered and check moisture daily. The weight of the tray on top helps seeds develop straight, strong stems.
When shoots are pressing against the blackout cover, move to light. The stretch in darkness builds stem length.
Water from below by setting the tray in water and allowing it to absorb upward — this avoids mould on the surface. Harve
At peak: Ready in 7-14 days — the fastest crop you can grow
Microgreens are instant gratification — from seed to harvest in under two weeks. Perfect for getting children interested in growing.
Seed nutrients are sufficient for the 8–12 day growing period.
Sow a new tray every 1-2 weeks year-round indoors. Each tray is a single harvest — cut at soil level when seed leaves are fully open. Keep 2-3 trays going at different stages so you always have something ready.
Something went wrong? Here is what likely happened and what to do differently next time.
What happened: Surface mold is caused by overwatering or poor airflow. It is different from the white root hairs that are completely normal and healthy — root hairs are orderly and attached to stems, mold is fuzzy and appears on the soil surface.
Next season: Water from below by setting the tray in water — never mist the surface once seeds have germinated. Ensure good airflow around the tray.
What happened: Damping off is a fungal condition that rots the stem at soil level. It is caused by overwet, poorly ventilated conditions — especially in the blackout phase.
Next season: Do not overwater during germination. Ensure the growing medium is moist but not wet before sowing. Improve airflow once seedlings emerge.
What happened: Patchy germination is usually caused by uneven seed contact with the growing medium, or the surface drying out during germination. Larger seeds like sunflower and peas benefit from pre-soaking.
Next season: Press seeds firmly into the surface after sowing. Soak larger seeds for 8 hours before sowing. Ensure the medium is thoroughly moist before you start.
What happened: Microgreens kept in blackout for too long become etiolated — pale, stretched, and weak. Once moved to light they should green up within hours. If they do not, they have been in darkness too long.
Next season: Move to light as soon as shoots are pressing against the blackout cover — usually day 3-5. They green up fast once in light. Do not wait until they look fully grown under the dome.
What happened: Microgreens dry out fast under grow lights or in a sunny window. They need consistent moisture from below during the light phase.
Next season: Water from below once a day during the light phase — set the tray in a shallow dish of water for 10-15 minutes and let it absorb upward.
Know what to look for before it gets out of hand — early identification is the most important step.
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