Tomato, pepper, eggplant and potato seedlings are the ones you should never eat. Penn State Extension leaves all four off its microgreen list because they hold toxic alkaloids at the stage you would harvest them. Those four are the toxic microgreens a home grower is most likely to run into, since the seed sits on every garden center rack in spring. Plenty of what else sits there works as a microgreen, as long as the seed is untreated.
Line those four names up and the pattern is easy to spot. They all sit in one plant family, and nightshade seedlings are the group name worth learning. Learn the family and you have learned most of the rule in one go. It beats checking each packet against a list every spring.
Alkaloids are what put these on the toxic microgreens list, and timing is what makes that matter. The warning covers the seedling stage, and that is the same stage a microgreen gets cut at. Grow a tomato to full size and you wait months, then eat only the ripe fruit, so the young leaves never reach your plate. Cut that same plant at two weeks old and the leaves go straight into the bowl.
Wild seed is the second exclusion and it draws less attention. Anyone who is not a plant expert should skip wild plants when growing microgreens. A seed you picked up on a walk can be a look-alike for something you would not want on a plate. A tray of young sprouts gives you almost nothing to identify it by. You have cotyledons and little else. Buy named seed from a supplier and the guessing stops.
Nightshade seedlings
- The four: Tomato, pepper, eggplant and potato all get left off the safe list.
- The reason: Each one holds toxic alkaloids while it is still at the seedling stage.
- No workaround: The seedling is the whole product, so there is no part to leave behind.
Wild plants
- The rule: If you are not a plant expert, do not use wild plants to make microgreens.
- Why it matters: A wild seed can be a look-alike, and you eat the shoot raw.
- Better move: Buy named seed so you know what is growing in the tray.
Treated seed
- The problem: Some seed is pre-treated with fungicide before it ever reaches you.
- What stays behind: Dyes, fungicides and insecticides could remain in the shoots you eat.
- What to buy: Seed labeled for microgreens or marked untreated, USDA certified organic if you can get it.
Garden soil and manure
- The risk: Garden soil, manure and compost may harbor bacteria.
- Containers: Wash any recycled container with soap and water before you sow in it again.
- Where it fits: This one is a growing rule, not a seed rule, so it applies to every crop on the safe list.
Treated seed is the trap that catches careful growers. Some seed is pre-treated with fungicide before it is sold, because it was meant to sit in cold field soil for weeks. You are cutting the shoot a week or two after sowing instead. Dyes, fungicides and insecticides could remain in the shoots you eat, so buy untreated seed and look for the certified organic label. Unsafe microgreen seeds are often just ordinary garden seed that was coated before it reached the shelf.
Sow only seed that is labeled for microgreens or marked untreated. If the packet says nothing either way, keep that seed for the garden bed and buy a different packet for the tray.
The safe list runs long enough that none of this costs you anything. Brassicas like broccoli and radish work. So do beet, chard, spinach, amaranth, lettuce and chicory. Carrot, celery, fennel, leek, onion and cucumber all belong there too. Cereals, quinoa, legumes, sunflower and flax are on it too, along with basil, cilantro, dill and chives. That is around twenty crops off a single list. Skip the four toxic microgreens and read the packet before you sow. Wild seed stays out too.
Read the full article: Microgreens: What Science Says and How to Grow
