microgreen
EdibleMustard Microgreens
Brassica juncea
Considered non-toxic to cats and dogs (source: ASPCA (Brassica, non-toxic)).
Some direct sun — an east or west window, or a few hours of direct light.
Keep evenly moist — water when the top inch of soil is dry.
Forgiving and beginner-friendly.
Mustard microgreens bring a sharp, spicy kick that the milder brassica trays do not, and they are just as fast and easy. Sow thickly, give a little light, and cut at the seedling stage in a week or two.
About Mustard Microgreens
Mustard microgreens (Brassica juncea) bring a sharp, horseradish-like kick that the milder brassica trays lack, and they grow just as fast and easily. At the seedling stage they go from sowing to harvest in a week or two. For a renter they need next to nothing: a shallow 2-litre tray and a little light on a worktop.
Sow the seed thickly across a shallow tray for a dense mat. A little light once the shoots are up keeps their colour and flavour strong. Cut them with scissors just above the soil at the seedling stage, usually in 8 to 14 days, then resow for the next batch. Like other microgreens this is a cut-once crop.
What it’s like to grow
Mustard microgreens are easy and quick, a low-risk way to add some heat to a plate. The common problems are damping-off, when a tray is sown too wet and crowded, and pale, stretched shoots in very low light. Give them a little airflow and modest light and they are trouble-free. They are non-toxic to cats and dogs, so the tray is safe around pets.
What to expect
First harvest in about 8–14 days. It’s forgiving, so it’s a good one to learn on. No sunny window? It also does fine under a clip-on grow light.
See what you’ll need to get started ↓Tips
- Sow densely across a shallow tray for a thick mat.
- A little light once they are up keeps the colour and flavour strong.
- Cut with scissors just above the soil and resow for the next batch.
Common problems
- Damping-off if sown too wet and crowded.
- Pale, stretched shoots in very low light.
Common questions
Is Mustard Microgreens toxic to cats and dogs?
Mustard Microgreens is non-toxic to cats and dogs, which makes it a safe pick if you have pets. Source: ASPCA (Brassica, non-toxic).
How much light does Mustard Microgreens need?
Mustard Microgreens does best in medium, indirect light: near an east or west window, or a little back from a bright one. Direct midday sun can scorch it.
How often should I water Mustard Microgreens?
Water Mustard Microgreens when the top inch of soil feels dry, then let it drain. Aim for evenly moist, not soggy.
What temperature does Mustard Microgreens need?
Mustard Microgreens is happiest around 15–24 °C. It tolerates brief dips to about 5 °C, but cold drafts and sudden chills set it back.
How long does Mustard Microgreens take to grow?
Expect a first harvest about 8–14 days from sowing under good conditions. A fast, spicy tray crop with a clear horseradish kick; sow densely and cut once at the seedling stage.
Can I grow Mustard Microgreens without a sunny window?
Yes. Mustard Microgreens does well under an affordable clip-on grow light, so a bright window isn't essential.
How big does Mustard Microgreens get?
Spicy seedling shoots sown densely as a tray and cut young.
How do I propagate Mustard Microgreens?
Sow seed densely across a shallow tray; no soaking needed.
What pests affect Mustard Microgreens?
Watch for fungus gnats. Check new growth and the undersides of leaves often, and treat early with a rinse or insecticidal soap before they spread.
Is Mustard Microgreens easy to grow?
Yes. Mustard Microgreens is forgiving and one of the better plants to learn on.
Gear for Mustard Microgreens
Gear suggestions to get you started — general picks, not paid placements.
Pet-toxicity from the ASPCA. Care details are general guidance, not professional or veterinary advice; only eat plants you can positively identify as the edible plant and part described. Photo: Goldlocki, CC BY-SA 3.0, via Wikimedia Commons (CC-BY-SA). Care info last updated 2026-06-08.