Watercress microgreens

Watercress is Nasturtium officinale.

**The crop this site calls nasturtium is Tropaeolum majus**, which is not in the genus Nasturtium and not even in the same family. And garden cress is Lepidium sativum, a third unrelated plant.

So three peppery greens in this directory carry a cress or nasturtium name, and no two of them are the same plant. The genus name went to the one nobody calls nasturtium, and the common name went to a plant from another family entirely, apparently because both taste of mustard oil. If you are buying seed on a common name, this is the corner of the shelf where that fails.

What it is, and how to tell you grew it right

Watercress microgreens are seedlings of Nasturtium officinale, in the Brassicaceae. No supplier opened here names a cultivar; the labels are crop and use names.

A correct tray is a dense, fine stand of slender stems carrying small rounded cotyledons, cut somewhere between full cotyledons and first true leaves. One supplier harvests at 5 cm.

Do not substitute "cress" for it when buying. Garden cress, Lepidium sativum, is sold under the same shortened word, is a different plant, and behaves differently in the tray: it is one of the fastest crops in this directory, where watercress is one of the slower ones.

This is much easier as a microgreen than as a crop. Field watercress wants running water and is genuinely difficult; its own supplier says the microgreen version is the easy way to get the flavor. That is worth knowing before the reputation puts you off.

What it tastes like, and what to do with it

Sharp and peppery, closer to mustard or radish than to a salad green. Both crop-specific sources agree, and one calls it bold.

That makes it a flavor element rather than a base: on sandwiches and canapes, with fish and eggs, through a potato or leek soup at serving, and anywhere a dish wants heat and a small tender leaf at once.

It is the wrong choice for anyone who wants mild, and the wrong choice for volume.

Nobody has measured whether it sharpens with age, so this page does not say it does.

Growing it: only what differs from the standard method

Two deltas, and the second is the one that matters.

No soak, stated outright by the crop-specific page rather than merely omitted.

Four to five dark days, uncovered at 1 to 2 cm. That is the only watercress-specific blackout duration published anywhere. No weight is verified for this crop: one extension says watercress benefits from covering, another gives a general two-to-five-pound contact weight, and neither of those is watercress data.

Then the real work, which is water discipline over a long cycle. Fine seed plus a slow crop is the combination that keeps a tray damp long enough for damping-off to take hold, and this page rates the mold risk high for that reason rather than because watercress is weak. Bottom-water, ventilate, and do not let the surface stay saturated.

Sow thickly but do not ask this page how thickly, because nobody publishes a rate. The supplier says 1/8 to 1/4 inch spacing, which is a spacing and not a mass, and converting one into the other would be arithmetic on a guess.

What goes wrong with watercress specifically

Damping-off, for the structural reason above. Rot at or below the medium line, collapse in patches, from the usual Pythium and Rhizoctonia complex. The mitigations are the ordinary ones and they matter more here than on a nine-day crop.

Uneven emergence on very fine seed, which is a distribution problem rather than a lot problem most of the time.

And one thing that is not a tray problem at all, but belongs on this page. Wild watercress growing in streams and ditches carries a real foraging hazard, and it is the reason some people are wary of the plant. A sown tray of purchased seed on clean medium indoors has nothing to do with that, and this page will not import a foraging risk into a growing guide. If you are picking watercress out of a waterway, that is a different question and a different source.

Nutrition, and one measured study

USDA FoodData Central has no watercress microgreen entry, searched 8 August 2026. The mature-watercress record is not a substitute, and on this crop that substitution is unusually tempting, because mature watercress has a famous nutrient reputation.

One peer-reviewed study did measure the microgreen. Marchioni and colleagues compared pot-grown watercress against four other Brassicaceae microgreens: seed germinated two days at 24C, grown at 30C day and 20C night on a 16-hour photoperiod, cut after 14 days at fully expanded cotyledons with first true leaves.

For watercress it reported 88.94 percent water, reducing sugars at 8.44 mg glucose equivalents per gram fresh weight, total carotenoids at 96.9 micrograms per gram, anthocyanins at 52.28 micrograms per gram, and total ascorbic acid in a reported group range of 124.1 to 137.52 micrograms per gram fresh weight. It also found watercress among the highest-antioxidant samples in the comparison.

Those are one study's measurements under one set of stated conditions, including a 30C day that most growers will not be running. They are not label values, and the antioxidant finding is a ranking within five crops rather than a general claim.

Which seed to buy

Buy by botanical name. This is the crop on this site where a common name is most likely to get you the wrong plant, and the three-way collision at the top of this page is why.

Specify Nasturtium officinale, untreated, sold for microgreen or food use, with a lot number and germination date. No cultivar choice is documented.

Then be ready for the price. Johnny's listed watercress microgreen seed at $296.25 a pound on 8 August 2026, which is the third most expensive seed per pound in this directory, behind mint at $1,394.50 and sorrel at $351.35, and ahead of oregano at $242.36.

What it costs per tray, nobody can tell you, and that is not evasion. There is no published seeding rate for this crop, so the price cannot be multiplied by anything. The formula is simply tray grams / 453.592 x $296.25, and the first term does not exist yet.

Is it worth growing?

Grow it for the flavor and the specificity, not for the numbers.

It suits a chef or a direct-market grower selling something recognizable and sharp, and a home grower curious about watercress without a stream. It does not suit anyone planning a yield, because there is no rate, no yield, no harvest window and no cost per tray for this crop anywhere.

If you want peppery and documented, the directory has better answers. Radish is measured end to end and faster. Garden cress, confusingly close in name and nothing like it in the tray, has a rate, a yield and a measured density study behind it.

Watercress wins when what you specifically want is watercress.

A note on the numbers above

The name collision at the top of this page is worth one more paragraph, because it is the only three-way one in the directory. Nasturtium officinale is watercress. Tropaeolum majus is what everyone calls nasturtium, and it is Tropaeolaceae, not even a brassica. Lepidium sativum is garden cress, a brassica but a different genus and a completely different crop in the tray: garden cress is among the fastest here and watercress is among the slower. All three taste peppery, which is presumably how the names got tangled, and all three are sold under overlapping words. The seed's botanical name is the only reliable way through it.

This crop has the price and not the rate, which is the exact reverse of thyme. Thyme has a measured rate and a measured yield and nobody will sell it by weight; watercress is sold by the pound at a price you can read off the page, and nobody has published how much of it goes in a tray. Between them they make the point this directory keeps arriving at: a cost per tray needs two numbers, and the microgreen literature reliably supplies one.

The days figure is the widest disagreement left on this site, 7 to 12 against 16 to 25, which is more than a factor of two on the same crop. One of those pages sells the seed for sprouting as well, and a sprouting timeline is a different thing from a microgreen one. This page keeps both rather than splitting the difference, because splitting it would produce a number neither source supports.

A blank means nobody has published that figure. Every crop here has a full research file; where no measured number exists this site leaves the cell empty rather than repeating an estimate. How the numbers work

All 61 crops, sortable, on the microgreen comparison.

Sources

• Watercress microgreen seed, Johnny's - the species, 16 to 25 days, the 1/8-to-1/4-inch spacing, the note that it is easier as a microgreen than in the field, the general 5-to-10-day storage range, and the $296.25 per pound price listed 8 August 2026.
• Watercress microgreen and sprouting seed, Premier Seeds Direct - 7 to 12 days, harvest at 5 cm, 4 to 5 blackout days with the 1-to-2-cm uncover signal, "Presoak: No", and the mustard-or-radish flavor comparison.
• Johnny's microgreen yield trial and the trial tech sheet - 29 varieties, none of them watercress, which is why this page has no rate and no yield.
• Marchioni et al., 2021, five Brassicaceae microgreens compared - N. officinale var. microphyllum at 14 days, 24C germination then 30C day and 20C night, with water content, reducing sugars, carotenoids, anthocyanins, ascorbic acid and antioxidant activity.
• USDA FoodData Central - searched 8 August 2026, no watercress microgreen entry.
• Microgreens, UF/IFAS Gardening Solutions - the note that watercress benefits from covering, the general second-harvest caveat, and 5 to 6 days refrigerated.
• Grow your own microgreens, Utah State University Extension - the general 2-to-5-pound contact weight, explicitly not watercress data.
• Damping-off, UC IPM - the pathogens behind the high risk rating.
• Microgreens production, Virginia Cooperative Extension - why seed density is system-dependent and needs a trial rather than a conversion.