Onion Microgreens
Onion Microgreens is a microgreen in the Amaryllidaceae family. It grows best in full sun with medium moisture, and is listed for USDA zones 5-10. Plants reach harvest about 14–21 days after planting and sit about 6 inches apart.
Varieties
3 from True Leaf Market · sorted by days to maturity▸Red Burgundy14–21 days
Heirloom
14 to 21 days. Red Burgundy Onion Microgreens are very rich in flavor and nutrients. Put just a couple greens on a sandwich or in a salad and taste the flavor! Best to start tasting small amounts so you can gauge how strong they really are!
View on True Leaf Market ↗▸Utah Yellow Sweet Spanish14–21 days
Heirloom
14 to 21 days. Utah Yellow Sweet Spanish Onion Microgreens are very rich in flavor and nutrients. Put just a couple greens on a sandwich or in a salad and taste the flavor! Best to start tasting small amounts so you can gauge how strong they really are!
View on True Leaf Market ↗▸White Sweet Spanish14–21 days
Heirloom
14 to 21 days. Onion Microgreens are very rich in flavor and nutrients. Put just a couple greens on a sandwich or in a salad and taste the flavor! Best to start tasting small amounts so you can gauge how strong they really are!
View on True Leaf Market ↗
Plant spacing
In a square-foot bed, space onion microgreens about 6 in apart — that fits 4 plants in each 1-foot square (2×2). Wider rows or containers space the same.
Plan your onion microgreens planting
Add onion microgreens to a free GardenDraft plan and get sow, transplant, and harvest dates computed for your ZIP code — with a drag-and-drop bed layout and reminders when it’s time to plant.
Start your free plan →At a glance
Storing & preserving
Stores well in the right conditions. Cure 2–3 weeks, then store cool, dark, and dry — keeps for months.
- Cure & store: Dry the necks/skins fully, then store in a cool pantry.
- Freeze: Freeze chopped for cooking (texture softens).
General home-preservation guidance — for tested processing times and safety, follow the National Center for Home Food Preservation.
Growing timeline
Companion planting — with cited sources
From US/Canada cooperative-extension publications and peer-reviewed studies. Evidence-tier dots show how strongly each recommendation is backed: ●●● peer-reviewed mechanism · ●● extension consensus · ● traditional knowledge with a plausible mechanism.
Pairs well with (24)
- Black WalnutEvidence tier B: Extension consensus across multiple US/Canada land-grant institutionsjuglone-tolerant
Onion and other alliums are juglone-tolerant; listed as 'safe under walnut' in extension tables.
Source: Penn State Extension, S8
- CarrotEvidence tier B: Extension consensus across multiple US/Canada land-grant institutionspest-deter
Onions emit sulfur-containing volatiles (allyl sulfides) that interfere with host-finding behavior of carrot rust fly (Psila rosae), the principal carrot pest in cool-temperate North America. Reciprocally, carrot foliage volatiles disrupt onion fly (Delia antiqua) host-finding by a similar olfactory-masking mechanism. Multiple US/Canada extension stations recommend perimeter or alternating-row onion/carrot intercropping for both crops.
Region: Effect strongest in maritime / cool-summer regions with high carrot rust fly pressure (Pacific Northwest, Great Lakes, Maritimes, New England).
Source: S1, UC IPM, S4, University of Guelph / OMAFRA
- ParsnipEvidence tier B: Extension consensus across multiple US/Canada land-grant institutionspest-deter
Parsnip is susceptible to the same carrot rust fly (Psila rosae) that attacks carrot; the allium-volatile masking mechanism applies equally to parsnip. Long parsnip season (often 120+ days) makes a perimeter allium row especially useful.
Region: Maritime and Great Lakes regions where carrot rust fly is severe.
Source: S1, University of Guelph / OMAFRA
- ArugulaEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles partial deterrent for flea beetle and aphids on arugula; shared brassica / allium rationale.
Source: University of Maryland Extension
- Asian GreensEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica / allium rationale as common cabbage.
Source: University of Maryland Extension
- Bok ChoyEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica / allium rationale; see common cabbage.
Source: University of Maryland Extension
- BroccoliEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica/allium rationale; see common cabbage.
Source: University of Maryland Extension, S13
- Brussels SproutsEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica / allium pairing rationale as common cabbage. Long brussels sprout season (often 90-120+ days) makes companion alliums particularly practical.
Source: University of Maryland Extension, S13
- Chinese CabbageEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica / allium rationale; see common cabbage.
Source: University of Maryland Extension
- CollardsEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica/allium rationale; see common cabbage.
Source: University of Maryland Extension, S13
- Common BeetEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Onion and beet are traditional bedfellows in extension home-garden guides; onion volatiles plausibly mask beet from leafminer flies, though direct trials are limited. Spatial use of bed is the main practical benefit.
Source: S1, University of Maryland Extension
- Common CabbageEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Onion volatiles are widely cited as a partial deterrent for cabbage maggot (Delia radicum) and brassica aphids; extension sources note the practice but acknowledge mixed results. The non-competing rooting depth (shallow onion vs. taproot brassica) supports interplanting.
Source: S5, University of Maryland Extension, S13
- Common KaleEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles cited as partial deterrent to cabbage aphid and cabbage maggot. See common cabbage for complete relationships.
Source: University of Maryland Extension, S13
- Common LettuceEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Onion's shallow roots and short canopy do not compete with lettuce, and onion volatiles are reported to reduce aphid colonization on adjacent leafy greens. Cited consistently in extension home-garden guides although controlled trials are scarce.
Source: University of Maryland Extension, S13
- Common SpinachEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles may mask spinach from leafminer flies; widely recommended in extension home-garden guides though direct evidence is limited.
Source: University of Maryland Extension
- Hamburg ParsleyEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Like parsnip and carrot, Hamburg parsley is susceptible to carrot rust fly attacking the storage root; allium-volatile masking provides modest protection.
- KohlrabiEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Same brassica/allium pairing rationale; see common cabbage.
Source: University of Maryland Extension, S13
- Romanesco Broccoli / CauliflowerEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles partial deterrent to cabbage maggot and aphids. See common cabbage for full discussion.
Source: University of Maryland Extension, S13
- RutabagaEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles cited by extension references as a partial deterrent to cabbage maggot (Delia radicum), the principal rutabaga and turnip pest. Shares the Brassica oleracea companion profile in broad strokes; see common cabbage for complete relationships.
Source: University of Maryland Extension, S13
- Siberian KaleEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Shares the broad brassica / allium pairing rationale; see common cabbage for full discussion. Siberian kale is more cold-hardy than B. oleracea kale and is often overwintered, extending the allium-companion window.
Source: S13
- StrawberryEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Onion is traditionally listed as a strawberry companion with the rationale that allium volatiles deter aphids and some foliar disease vectors; empirical support is weak but the practice is cited by multiple extension home-garden references.
Source: University of Maryland Extension
- Summer SavoryEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Summer savory is recommended near onions in extension home-garden guides; plausible volatile masking effect against onion thrips and onion maggot fly.
Source: University of Maryland Extension
- Swiss ChardEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium-chard pairings appear in Northeast extension home-garden guides on the same rationale as beet-onion: alliums may mask leafminer host cues; primary benefit is bed efficiency.
Source: University of Maryland Extension
- TurnipEvidence tier C: Traditional practice with plausible mechanism but limited empirical replicationpest-deter
Allium volatiles cited as partial cabbage maggot deterrent; particularly relevant for root brassicas like turnip where maggot damage destroys the marketable yield.
Source: University of Maryland Extension, S13
Sources cited
- S1
- Cornell University Cooperative Extension — vegetable production guides
- S13
- University of New Hampshire Extension
- S23
- University of Guelph / OMAFRA (Ontario)
- S3
- UC IPM (University of California Agriculture and Natural Resources)
- S4
- Oregon State University Extension Service
- S5
- Michigan State University Extension
- S6
- Penn State Extension
- S8
- Iowa State University Extension and Outreach
- S9
- University of Maryland Extension — Home & Garden Info Center
Care & troubleshooting— extension-sourced, with citations
When to feed, prune & water
Feed alliums in spring
Feeding- Routine careFeed nitrogen every 3 weeks during active growth· every 3 wks · ~9 wksmoderate evidence — extension confidence
Alliums build the bulb from spring leaf growth. Feed a nitrogen source every ~3 weeks through spring, then stop once bulbs start to swell so they cure well.
Floating row cover timing
ProtectionUnusual this time of year.
- Routine careCover at planting and seal the edgesstrong evidence — extension confidence
Lay floating row cover over the crop right at seeding or transplanting and bury the edges with soil so pests can't get under; don't cover ground where the same crop grew last year, since overwintered pupae would emerge inside.
- Routine careRemove at flowering for pollinated cropsstrong evidence — extension confidence
On crops that need insect pollination, take the cover off once flowering begins so bees can reach the blooms; on self-pollinated or leafy crops you can leave it longer.
Something looks wrong?
Describe what you see on your onion microgreensand we'll rank the likely causes — most likely first, least-invasive fix first.
Bacterial soft rot
Diseasesevere- CulturalRemove rotting plants and produce (manage, not cure)strong evidence — extension confidence
Soft rot can't be cured once tissue breaks down; promptly remove and discard affected plants and produce so the bacteria don't spread to neighbors or other stored vegetables.
- CulturalAvoid wounds and excess moisturestrong evidence — extension confidence
Harvest in dry conditions, handle gently to avoid bruising, control insects that create entry wounds, and improve drainage; cure and store bulbs and roots cool and dry.
- CulturalDon't overwater and rotatemoderate evidence — extension confidence
Avoid waterlogged soil and overhead watering that splashes bacteria, and rotate away from previously affected fleshy crops to lower disease pressure.
Onion & garlic white rot
Diseasesevere- CulturalRemove infected plants and soil carefullystrong evidence — extension confidence
Dig and discard affected plants along with the surrounding soil to avoid spreading the long-lived sclerotia; clean soil off tools and boots, since this fungus can persist in soil for many years.
- CulturalAvoid moving infested soil and replantingstrong evidence — extension confidence
Don't replant alliums in known-infested ground; while rotation alone won't clear it, avoiding the area and not spreading contaminated soil is the most reliable home approach.
Leafhoppers & aster yellows
Diseasemoderate- CulturalRemove infected plants and weed reservoirsstrong evidence — extension confidence
Aster yellows can't be cured, so pull and discard plants showing yellowing and witches-broom, and clear nearby weedy hosts that harbor the phytoplasma and its leafhoppers.
- CulturalExclude leafhoppers with row covermoderate evidence — extension confidence
On young susceptible crops, a floating row cover keeps egg-laying leafhoppers off and lowers the chance of aster-yellows spread.
Leek moth and thrips on leeks
Pestmoderate- CulturalCover and clean upmoderate evidence — extension confidence
Cover plants with insect netting or row cover at planting to keep egg-laying leek moths and thrips off, and remove and destroy badly infested leaves and crop debris. Rotate alliums to a new spot each year to break the pest cycle.
- OrganicWash off thrips or spray· every 1 wkmoderate evidence — extension confidence
For thrips, hose plants down to dislodge them, or apply a labeled insecticidal soap or neem product per the label. For leek moth caterpillars, a labeled spinosad or Bacillus thuringiensis product applied per the label when young larvae are active can help.
Leek rust
Diseasemoderate- CulturalImprove airflow and remove infected leavesmoderate evidence — extension confidence
Leek rust is a fungal disease favored by damp, crowded conditions and lush growth; space plants well, avoid over-feeding with nitrogen, and remove badly affected leaves. Mild cases usually still produce a usable crop, and rotating alliums each year helps prevent buildup.
Onion thrips
Pestmoderate- CulturalOverhead-water and remove debris· every 3 days · ~3 wksmoderate evidence — extension confidence
Thrips dislike moisture; overhead irrigation and weed/debris cleanup reduce them. Reflective mulch deters them on young plants.
- OrganicInsecticidal soap/spinosad - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
For heavy pressure a labeled soap or spinosad on a weekly schedule helps. Follow the label.
Cabbage & onion root maggots
PestmoderateUnusual this time of year.
- CulturalCover at planting with floating row coverstrong evidence — extension confidence
Place floating row cover over the crop at seeding or transplanting and bury the edges so flies cannot lay eggs at the stem base; do not use if the same crop grew there last year, since trapped pupae would hatch underneath.
- CulturalRotate and delay plantingstrong evidence — extension confidence
Rotate susceptible crops to a new spot each year and, where possible, delay planting to late spring to miss the main egg-laying window.