Plant of the Week #8: Nasturtium officinale

In most parts of the country, spring has undoubtedly begun to creep back into the landscape, however subtle that may be in some places. The lengthening days and strength of the sun is unmistakable and fills us with encouragement and hope for yet another prosperous and bountiful growing season. As such, many plants are beginning to show themselves as they put forth their first flush of green leaves after a long, cold winter. Many of the earliest plants to reveal themselves (even when temperatures are barely tipping above freezing) are members of the mustard family (Brassicaceae) which includes some of our favorite and most familiar garden vegetables.

Watercress (Nasturtium officinale) is one of those mustard family plants that is eager to get going at the start of the growing season, even when the nights can still be a little frosty. Throughout southern Canada, watercress can often be found very early in the season, often when the nights are still frosty. It is without a doubt a cool season crop, just like many of the mustard family plants which we have domesticated and cultivate widely. Watercress has a tendency to grow well throughout the spring and then shy away during the heat of the summer before returning yet again as conditions become cooler in the autumn. As if the name weren’t enough of an indication, N. officinale is a moisture loving herbaceous perennial that is native to most of what is now Europe as well as parts of North Africa and northwestern Asia.

Although watercress can be found growing along the margins of ponds or populating the fringes of shallow ditches and creeks in full sun or dappled shade throughout the growing season, it is undeniably at it’s best (from a gastronomic perspective) during the spring and autumn. At this time of the year, the sun has not yet become so intense as to bake the ground dry and the night air is still cool enough to promote condensation and dew. Adequate moisture is unsurprisingly a prerequisite for watercress, and without shallow, gently flowing water  and rich loamy soils this plant will not succeed.

As with most members of the Brassicaceae, watercress bears dainty, 4-petaled white flowers atop short stalks which produce bean-like pods (properly known as siliques) which contain many small, round seeds. The distinctive rounded lobes of the pinnately compound leaves grow alternately along fleshy hollow stems which produce roots along their entire length wherever they make contact with the water. The stems only grow about 6-8 inches off the ground because they’re weak and have difficulty supporting themselves, encouraging the plant to flop over, produce more roots and continue growing and creeping and spreading as quickly and thoroughly as possible.

Luckily for those of us that live outside of (what is believed to be) the native range of watercress, early European colonialists had the forethought to bring over cuttings of individual plants to grow in suitable habitats in North America. Since being deliberately introduced as a food, watercress has naturalized and can now be found in the same sort of habitats here that it preferred in Europe. From my personal experience and observations, watercress is not nearly as abundant in North America as it likely is in Europe but when one encounters watercress they are often overwhelmed by it’s abundance. I most certainly was.


Watercress, when introduced to a suitable area either intentionally or not (perhaps as a fragment of root or even a single leaf stuck to the bottom of one’s shoe) this plant has the capacity to envelope the  habit completely and totally without hesitation, most often reproducing vegetatively and sprawling to cover the water’s surface when and where it can. The smallest piece of a mature plant can form roots and reestablish itself in new locations; undoubtedly this is what has lead to the plant’s continued success as a recent migrant here in North America.

This activity produces a dense mat of leaves that discourages other plants from being able to gain a foothold and threaten it’s claim over that particular creek, ditch or pond margin. This dense growth habit also makes collecting the plants extremely efficient and a multitude of the fresh greens can be gathered within minutes. My preferred method for harvesting watercress is to simply grasp a hand full of the shoot tips with one hand and use either a serrated knife or pair of kitchen sheers to cut the plants off a few inches from where they meet the surface of the water.

This allows you to collect only the uppermost tender sections of plant for consumption as well as to leave some leaves and dormant buds behind which will encourage the plant to regrow, which it does with increased vigor and urgency. Harvested in this sustainable manner, I fathom that one could get at least 4-6 cuttings of watercress from a given area of plants throughout the entire season.

Those harvests ought to be concentrated in the spring and fall as in the summer heat watercress ‘bolts’ (produces flowering stalks and with reduced foliage) and after shedding it’s seeds often dies back for a few weeks before resuming growth in late summer and early autumn. All of these procedures and considerations are part of what I like to call a respectful harvesting ethic, where each individual considers both the positive and negative implications of acting upon a plant and it’s habitat in a certain way as to limit or cause no foreseeable damage. This ethic can be applied and ought to be specified to each and every individual plant species that one wishes to interact with and experience.

By developing a thorough understanding of a plants identify, life cycle and the larger plant communities and landscapes to which that plant belongs to, foraging can be carried out in a way that not only doesn’t degrade a given habitat but rather  improves it over time. Collecting and propagating useful plant species (when appropriate i.e. aggressive non-native species) with the intention of introducing them to new areas after utilizing them is part of my own personal ethic, as I am assisting the plant to continue it’s life elsewhere (whether in the form of a cutting, division or seed) and to become more abundant for our mutual benefit.


Anyhow, why would one want to bother with the effort of collecting wild watercress or taking some from a wild spot and cultivating it in habitat closer to home? Watercress is an incredibly nutritious vegetable which contains significant amounts of vitamin A, B6 and C, iron, folic acid, manganese, iodine and calcium. It is also believed to be one of the first vegetables to be consumed by human beings when they first began colonizing areas where the plants naturally occurred.

It is hardy, disease resistant, prolific and easy to propagate, all characteristics which make it a highly desirable crop. The flavor of watercress changes over the course of the season and is also dependent upon the availability of water during the entire year. During the summer when conditions are often dry and while the plant is in flower and setting seed, the flavor of watercress is hot, pungent and quite bitter. However, during the wetter, cooler seasons (April through to May and September to November) the flavor is more mild and delicious, with a slight pepperiness which adds brightness and livens up many different dishes.

I find fresh watercress in a salad, lightly sautéed in a stir fry or added to a pot of soup or stew just as it has been removed from the heat and stirred in to be my favorite ways of enjoying this bountiful and nutritious herb. One caution that I must mention when it comes to foraging for watercress is to ensure that the area in which you are collecting it has limited or no identifiable sources of pollution, as waterways in southern Ontario and also elsewhere are unfortunately often contaminated with a rainbow assortment of different chemical or organic pollutants, such as petroleum based fertilizers, road salt or gasoline runoff from nearby roads and/or parking lots.

One last word on watercress: The genus name for watercress (Nasturtium) is confusingly the common name of a related plant that is identified by the botanical name Tropaeolum majus. This species is tropical in origin and looks very much different from watercress, having bright, showy flowers with round leaves and is altogether an entirely different plant. This is one more piece of evidence which points towards using the botanical names of plants when discussing them as common English names often overlap with one another and needlessly complicate things.