The GuideMicrogreens Vol. 012

Microgreens mix

grown indoors, any week of the year

Arugula microgreens are baby arugula plants that you harvest very young, when they are just a couple of inches tall, for a bold peppery, spicy flavor. They are one of the fastest microgreens to grow: scatter about 10 grams of seed thickly on a damp tray, cover it to keep it dark for a day or two while the seeds sprout, then move it into bright light to green up, and snip in about 6 to 8 days (a bit longer in a cool or dim room). Arugula seed gets sticky when wet, so mist it instead of soaking. You grow them indoors all year on a shallow tray of seed-starting mix or a special growing mat, so there is no outdoor season or weather to worry about, and they grow the same way no matter where you live. Use them fresh on salads, sandwiches, and as a garnish.Arugula microgreens are the young seedlings of arugula (Eruca sativa, in the mustard family), harvested at the cotyledon to first-true-leaf stage for a concentrated, distinctly peppery, spicy bite that is the whole reason to grow them. They are among the fastest microgreens: a dense, even sow of about 10 g per 1020 tray, a short blackout of about 1 to 2 days to even the stand, then 18 hours of light to green up, cut in roughly 6 to 8 days (longer, closer to 10 to 12 days, in cooler or lower-light rooms). The seed is small and mucilaginous, so it is misted rather than presoaked, or it clumps. Grown indoors year-round on a shallow tray of mix or a fiber mat, arugula microgreens need no frost, season, or hardiness zone, so the same tray grows identically on a windowsill anywhere. They are used fresh as a peppery salad base, sandwich layer, or garnish.

Arugula Microgreens, ready to cut
Fig. 01 · Arugula MicrogreensIndoor
Ready in
7-12
days, sow to harvest
Difficulty
Easy
beginner crop
Grows
Indoors
year round, any season
Resow
Weekly
for a steady supply
The cycle, start to finish

Sow, dark, light, harvest, then again

Indoors, every week of the year. Most mixes are ready in 7 to 12 days; start a fresh tray every week for a steady supply.

  1. Step 01 Day 0

    Sow

    An even, dense scatter of seed across the whole surface with no bare patches and no thick clumps. The mix underneath should look evenly damp and dark, not soggy or pooling.A uniform, dense seed layer with no gaps or clumping on evenly moist medium.

    From plant Dampen the growing medium so it feels like a wrung-out sponge, then scatter about 10 grams of seed thickly and evenly. Do not soak arugula seed; it turns sticky and clumps, so just mist it. Press the seeds down so they touch the surface, but do not cover them with soil.Pre-moisten the medium to wrung-sponge feel, then broadcast about 10 g of seed densely and evenly across a 1020 tray. Do not presoak arugula: the seed is mucilaginous and clumps when soaked, so mist to wet it. Press seed into contact but do not bury it; buried seed greens poorly and traps moisture against the stems.
  2. Step 02 Covered · ~74°F

    Germination

    The seeds swell, split, and push out tiny white roots, then pale looped stems that lift the cover slightly. Under the cover everything looks pale and leggy, which is exactly right at this stage.Seeds imbibe and split; white radicles emerge, followed by pale hooked hypocotyls lifting the weighted cover.

    From plant Put the cover on and keep the tray warm (around 74 °F) and dark. Mist lightly so the surface stays damp but not wet. A small weight on the cover helps the roots push down.Cover the tray and keep it warm (about 74 °F) and dark. Mist to hold even surface moisture, never soggy. A light weight on the cover keeps seed in firm contact so roots drive down rather than lifting the seed.
  3. Step 03 1 to 4 days · dark

    Blackout

    A dense mat of pale, stretched stems standing tall and lifting the cover. The stems will be yellowish or white, not green yet, and that is normal in the dark.Uniformly elongated, blanched stems lifting the cover; a tall, even stand pre-greening.

    From plant Keep the covered tray in the dark for a day or two. The darkness makes the stems grow taller and more even before you give them light.Hold the weighted cover in the dark for arugula's short blackout, about 1 to 2 days, then flip the cover off the canopy so it shades without touching. The dark stretch lengthens and evens the stems before greening.
  4. Step 04 18 h light · 68 to 72°F

    Light

    The stems and seed leaves turn from pale to bright green within a day or so. Soon a small, ruffled first true leaf may appear at the center, and the tray starts to smell peppery.Rapid greening of cotyledons; first true leaf may form. Peppery aroma develops.

    From plant Uncover the tray into bright light for about 18 hours a day at 68 to 72 °F, and start watering from the bottom so the leaves stay dry. Keep a gentle fan going to prevent mold. Cut when the first little leaves are open, usually about a week.Uncover into 18 hours of bright light at 68 to 72 °F and switch from misting to bottom-watering so foliage stays dry. Run a gentle fan; the dense canopy plus high humidity is the damping-off window. Cut at cotyledon to first true leaf, about 6 to 8 days, before the flavor turns harsh.
  5. Step 05 Day 7 to 12

    Harvest

    Open, fully green seed leaves standing about one to two inches tall, sometimes with a tiny true leaf just showing. They should taste bright and peppery.Cotyledons fully expanded and green at 1-2 in, first true leaf just emerging; peppery flavor developed.

Then start again. Sow a fresh tray every week, and there is always a crop a few days out.
The specs

Care guide

The numbers that matter, at a glance.

Sunlight
bright indirect light or a grow light
Water
mist to keep the medium evenly moist through blackout; bottom-water once greened so the leaves stay dry
Days to maturity
7-12 days
Container OK?
Yes
Germination temp
65-75°F
Soil chemistry

Soil pH for arugula microgreens

You do not need to worry about soil pH for arugula microgreens. The mixes and mats sold for microgreens are already fine as they are.pH is not a practical lever for a single short indoor cycle on a soilless medium; standard seed-starting mixes and coir sit in a workable range and need no adjustment for arugula.

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Steady hand on the hose

Watering

When & how much
Frequency
While the seeds are sprouting, lightly mist the surface once or twice a day so it stays damp. After you move the tray into the light, water from the bottom whenever it starts to dry out.Mist once or twice daily through germination and blackout to hold even surface moisture; once greened, bottom-water as the tray dries.
Amount
Just enough to keep the soil damp like a wrung-out sponge, never soggy. After bottom-watering, tip out any water left sitting in the tray.Enough to keep the medium at wrung-sponge moisture, never saturated; pour off any standing water after bottom-watering.
Method
Mist the top while the seeds are sprouting, then water from the bottom once the leaves are up so the leaves stay dry.Mist during germination and blackout; switch to bottom-watering once the canopy is up so foliage stays dry.
Signs of trouble
Too much water
Water sitting in the tray, a bad smell, fuzzy white mold, or seedlings flopping over mean it is too wet. Cut back on water and improve airflow.Standing water, a sour smell, fuzzy white growth on the medium or stems, and collapsed seedlings all signal overwatering and the damping-off that follows it.
Too little water
Limp, curling leaves and soil that has shrunk away from the sides mean it got too dry. Water from the bottom right away.Curling, limp cotyledons and a medium that has pulled away from the tray edges indicate the canopy has dried too far between waterings.
Feeding rhythm

Feeding

Frequency
none
Type
none needed
When to start
not applicable

You do not need to feed arugula microgreens. The seed carries enough food to reach harvest, and adding fertilizer just invites algae and odd flavors.Arugula microgreens are cut before they exhaust the seed's own reserves, so no fertilizer is needed for a single cycle on an inert medium or seed-starting mix. Added nutrients mainly raise the risk of algae and off-flavors; a hydroponic grower who wants to feed at all needs only a dilute 50 to 100 ppm nitrogen solution.

Harvest signals

When to pick

Your arugula microgreens are ready when the first little seed-leaves are open and, for many, the first true leaf is just showing, usually about 6 to 8 days after sowing and around 1 to 2 inches tall. Cut them while they are young for the best peppery flavor, before the bigger leaves come in. Snip them just above the soil with clean scissors and eat them fresh. They do not grow back, so you start a new tray each time.Cut at the cotyledon to first-true-leaf stage, typically about 6 to 8 days from sowing (up to roughly 10 to 12 in cooler or lower light), when the stand is a couple of inches tall and bright green. Harvest before the true leaves and stem fiber develop, since that is when the flavor shifts from pleasantly peppery to harsh. Snip just above the medium with clean scissors; the stand will not regrow, so the tray is a single cut.

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Yield

What to expect

You measure microgreens by the tray, not by each plant. A full 1020 tray of arugula gives you a few good handfuls, around 5 ounces.Yield is measured per tray, not per plant: a well-sown 1020 tray of arugula returns roughly 5 ounces of cut microgreens (Penn State reports about 148 grams, near a third of a pound, over a two-week cycle).

Each tray gives one harvest at its best. To keep a steady supply, start new trays every few days.Every tray is a single harvest at peak; continuous supply comes from staggered sowings, not from regrowth. There is no waiting period with microgreens. Your very first tray works just like the rest; you will just get a feel for how much to sow and water after a few tries.There is no establishment year; the first tray performs the same as any later tray. Expect to dial in seeding rate and watering over the first few cycles.

What changes yield
seeding density (too sparse wastes the tray; too dense traps moisture and invites mold)even moisture and the mist-to-bottom-water transitionconstant gentle airflowseed freshness and using microgreen-grade seedlight intensity and the full 18-hour daily duration
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Pick your variety

Recommended varieties

The arugula you will almost always grow as a microgreen is regular salad arugula (Eruca sativa). It is one of the fastest microgreens, ready in about 6 to 8 days, with a bold peppery flavor. Its seeds get sticky and gel-like when wet, so mist them instead of soaking, or they clump. There is also a wild or wasabi arugula (Diplotaxis) that grows more slowly and tastes even spicier. Whichever you pick, use seed sold for sprouting or microgreens, and cut while the little seed-leaves are open for the best flavor.Almost all arugula sold as a microgreen is standard salad arugula (Eruca sativa): a fast brassica, roughly 6 to 8 days to a peppery cut, sown at about 10 g per 1020 tray with no presoak. The seed is mucilaginous and forms a gel coat when wet, so mist it rather than soaking it, or it clumps and germinates unevenly. Wild or wasabi arugula (Diplotaxis tenuifolia) is a different genus that runs slower and tastes sharper; treat it the same way at sowing but expect a longer, spicier crop. Use untreated, microgreen-grade or food-safe seed, and cut at the cotyledon to first-true-leaf stage, before true leaves and fiber turn the flavor harsh.

Standard (salad) arugula
Eruca sativa, the common microgreen arugula. Fast, about 6 to 8 days; peppery. No presoak; mist, do not soak the mucilaginous seed. About 10 g per 1020 tray.
Wild / wasabi arugula
Diplotaxis tenuifolia, a different genus. Slower to grow and sharper, more pungent than salad arugula; deeply cut leaves. No presoak. Grown less commonly as a microgreen.
Off the vine

Storing your harvest

Room temp
Do not leave cut arugula microgreens out on the counter. They go limp fast, so put them in the fridge right after cutting.Do not hold cut arugula microgreens at room temperature; they wilt and spoil within hours. Refrigerate immediately after cutting.
Fridge
Keep cut arugula microgreens in the fridge in a container with a paper towel to soak up extra moisture. Most last about 5 to 7 days. They keep best cut dry, so hold off on watering for half a day before you harvest.Refrigerate dry in a vented container lined with a paper towel; most cut arugula microgreens keep about 5 to 7 days. Cut when the foliage is dry (skip watering for a half day before harvest), since surface moisture shortens shelf life on a crop that is not washed after cutting.
Freezer
Do not freeze arugula microgreens. Freezing turns them mushy. They are meant to be eaten fresh.Not recommended. Freezing collapses the delicate cells and ruins the texture. Arugula microgreens are a fresh, cut-and-eat crop.
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The usual suspects

Pests & diseases

Pests
Fungus gnats
P · 01
What it is Tiny dark flies that show up around constantly damp soil, where their larvae live. They are the main bug you might see indoors, and they usually mean the tray is staying too wet. Arugula grows so fast you often cut before they build up.Small dark flies whose larvae live in persistently wet medium and feed on organic matter and tender roots. They are the main indoor microgreen pest and a symptom of an over-wet tray rather than a primary threat, and arugula's fast 6 to 8 day cycle usually beats them.
Diseases
Damping-off and moldDamping-off (and surface mold)
D · 01
What it is The most common microgreen problem. In wet, crowded, stuffy conditions, tiny fungi rot the baby plants right at the base, and you often see fuzzy white or gray mold on the surface. Arugula's crowded leaves and sticky-when-wet seed make good airflow and careful watering matter even more.Soil-borne fungi rot seedlings at the soil line under wet, crowded, still conditions, often alongside fuzzy white or gray surface mold. It is the number-one microgreen failure, and arugula's dense fine canopy plus its mucilaginous seed, which holds water at the surface, make even moisture and airflow especially important.
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Every date, temperature, spacing, and recommendation on this page is sourced from university cooperative extension publications, peer-reviewed agricultural research, NOAA climate data, and direct extension calendars. Where claims are softer (traditional gardening wisdom not formally documented), we say so.

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Well-grounded A known agronomic principle, but not formally tested for this specific pair
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Last reviewed
July 2, 2026
Data version
crops_data_final · v1.0 · schema 2.9
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16 publications
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Companion-planting claims tagged inline · zone dates verified against 5+ extensions
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  • Virginia Cooperative Extension 426-331 vce_426_331
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Vol. 012 · Arugula Microgreens · plant.lifestyle