Watercress
Nasturtium officinale
Botanical family: Brassicaceae
A semi-aquatic Brassicaceae with rounded dark-green leaves, a hollow stem, a creeping or floating habit. Harvested from September to May in watercress beds, and from May to September in the garden, two months after a spring sowing. Classic preparations: salad, pesto, velouté soup, sauce. A remarkable supply of vitamin C according to the Ciqual tables.
Cool partial shade
Bed of gravel or sand, clear running water 10-15 °C
Permanent running water (not advised in still water)
Hardy as long as the water doesn't freeze deep down
Overwinters in your zone
Insect-pollinated (small white flowers May-October)
Role in permaculture
The running-water plant par excellence: difficult to integrate into a still pond but ideal at the outlet of a lagoon or in an artificial rivulet fed by a solar pump, where it provides a spring leaf vegetable.
Good companions
Traditional companion planting (benefit not demonstrated)
Insects attracted or useful
Seasons & availability
Sown from March to July, under a frame then outdoors or in a trough, in soil kept soaking wet or in running water; leaves are taken in successive cuts about two months after sowing in the garden, from May to September, and from September to May in a watercress bed, where spring water allows cutting even in winter.
Available: January, February, March, April, May, June, July, August, September, October, November, December.
Guidance for the oceanic / temperate climate; it may vary with your region, altitude, exposure and growing method.
Sources
- La Ferme de Sainte Marthe, « Réussir la culture du cresson de fontaine » (fermedesaintemarthe.com/en/blogs/comment-reussir-la-culture-de/reussir-la-culture-du-cresson-de-fontaine)
- Cressonnière Sainte-Anne, « Comment se cultive le Cresson de Fontaine ? » (cressonniere-sainte-anne.fr/comment-se-cultive-le-cresson-de-fontaine/)
- Plants For A Future, « Nasturtium officinale » (pfaf.org/user/Plant.aspx?LatinName=Nasturtium+officinale)
Nutritional & medicinal properties
For educational purposes. Not a substitute for medical advice. Effects depend on the form, the dose and personal context.
Precautions & contraindications
A real parasitic risk: harvested raw in a natural setting where cattle, sheep, or goats graze upstream, watercress can carry the larvae of the large liver fluke (Fasciola hepatica), the agent of fascioliasis. Washing, vinegar, and partial cooking are not enough; only complete cooking destroys the parasite. Do not harvest in stagnant, soiled, or uncertain-origin water; reserve raw consumption for watercress from a controlled bed, otherwise cook before eating. There is also a confusion risk: the same water grows Apiaceae with similar foliage, including fool's water-cress (Helosciadium / Apium nodiflorum) and above all hemlock water-dropwort (Oenanthe crocata), one of the most toxic plants in France (deadly), true watercress has compound leaves with a large rounded terminal leaflet, a peppery mustard taste, and never bears an umbel of white flowers. At the slightest doubt about identification, refrain. Traditional medicinal use at a high dose is not advised in case of kidney failure. For cultivation fed by rainwater (lagoon outlet, artificial rivulet), take into account the PFAS present in rainwater (Cousins et al., 2022): see the concept 'Rainwater quality'.
Family behaviour: Brassicaceae
In general, Brassicaceae produce glucosinolates, sulphur compounds with a mild biocidal effect on the soil (a biofumigant effect, sometimes sought between two sensitive crops). Members of the cabbage and mustard family, they are prone to the cabbage white and clubroot.
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Species & varieties
The best-known species and varieties in France.
Species
Common varieties
Voices of peoples
Paraphrases attributed to their documented sources. Never an invented quote.
Medieval European monastic tradition · Rhineland, 12th century
Hildegard of Bingen, in her Physica, ranks watercress among the plants that 'restore the humours of the blood'. The monastic tradition made it a precious Lenten vegetable, grown near the abbey fountains. The Norman proverb sums it up: 'Eat watercress in March, and you'll have health all year.'
Hildegard von Bingen, Physica (Liber simplicis medicinae), composé entre 1151 et 1158, livre I, chapitre sur le cresson.
Before you forage
This plant is often gathered from the wild. Only pick what is abundant, never a protected species, and never uproot a whole plant (roots) without the landowner's permission. Rules vary by country and region, check locally.
Key takeaways
- • Prefers cool partial shade exposure.
- • Ideal soil: bed of gravel or sand, clear running water 10-15 °c.
- • Classic companion: Water mint.