Watercress (Nasturtium officinale)

By Diana Wind, RD (wind)
April 16, 2010

The more you learn about watercress, the more likely you are to include this tasty member of the mustard family in your diet. Discover gardening information about watercress, and why scientists find this nutrient-rich herb so fascinating.

Watercress enhances nutrition in recipes while adding a unique, peppery flavor to foods. You will find that watercress (Nasturtium officinale) and garden cress (Lepidium sativum) may be referred to interchangeably as the same herb. Sometimes watercress in grocery stores may actually be garden cress. Does it matter? Not really. Gardeners, chefs and home cooks enjoy growing and cooking with them both.

You will also find even more varieties of cress to consider for your garden, such as the bienniel upland cress (Barbarea verna). For now we will focus on watercress and its twin, garden cress.

 Watercress

The name Nasturtium officinale could easily get confused with the familiar nasturtium (Tropaeolum majus and T. minus) that is grown for colorful, edible blooms. Indeed, Nasturtiums are peppery in flavor too; however, they are members of the Tropaeolaceae family and not botanically related to watercress. Both watercress and garden cress are members of the mustard family, Brassicaceae. Another Brassicaceae family member that sometimes gets misrepresented as watercress is common scurveygrass (Cochlearia officinalis).

Common names for watercress include water radish, water rocket and hedge mustard. If you plan on researching for seed sources or more information about watercress, you may come across these scientific synonyms: Rorippa nasturtium aquaticum, R. nasturtium, or Sisymbrium nasturtium aquaticum. 

With pale yellow to white blooms atop branching succulent stems, this perennial is hardy in zones 5b to 11. Being an aquatic plant, watercress has high moisture needs. Watercress grows along ponds and streams, and can also be grown in pots with the bottom of the pot submerged in 2 to 3 inches of water. Stems will produce sideshoots as they grow. When harvesting it's best not to cut too low on the stems, to allow for sideshoot growth to continue. Store purchased watercress, with roots, can be planted or preserved for a few days if kept in a vase of water.

According to the National Gardening Association (NGA) editors, Watercress prefers clean, moving water. "First harvest may be taken after 30 to 45 days and it may there after be harvested every 40 to 80 days."

Commercially grown watercress is often hydroponically cultivated, with best production in slightly alkaline conditions.

Watercress Weeds
Once established, watercress plants send runners from the mother plant. The USDA reports noxious weed status in Connecticut.^[1] And the Food and Agriculture Organization of the UN reports invasivness along the rivers of New Zealand.^[2]

 Watercress Nutrition

The familiar exhortation, "Eat your vegetables" is said for good reasons, mainly for a healthier body. Add watercress to your veggie list! Nasturtium officinale is among the list of cancer fighting cruciferous vegetables that include cabbage, bok choy, broccoli, cauliflower, arugula, kale, collards, mustard greens, turnips, Brussels sprouts, kohlrabi, rutabaga, horseradish and radish.

Watercress contains beneficial phytonutrients, and according to the USDA just 10 sprigs of watercress (25g) will provide an excellent source of Vitamin K* - 63mcg (78% DV); a good source of Vitamin A - 798IU (16%DV); and Vitamin C -11mg (18% DV). Watercress also contains many other nutrients including Calcium, Magnesium, Potassium, Thiamin, Riboflavin, Folate and trace amounts of 18 beneficial Amino acids.

As a medicinal plant, Nasturtium officinale has long been used in herbal home remedies by the people of the southeastern region of Iran and in other parts of the world. Medicinal claims from using the fresh aerial parts or juice of the plant include: preventing scurvy (antiscorbutic), blood cleansing, digestive tonic (stomachic), and diuretic actions.

Studies show that watercress reduces oxidative stress and increases antioxidant capacity in animals.^[3] For years scientists have been studying molecular components found in watercress, such as isothiocyanates, and phytonutrients that fight against free radical oxidation - a hot topic for medical researchers in the fight against many clinical disorders, including cancer.*

 Garden Cress

Garden cress, sometimes called pepperweed, is easy to grow and does not require as much water as watercress. Instead, this healthy green prefers moist, but moderate watering. With over 48 species in Lepidium, you will find a nice selection of garden cress seeds available from suppliers.

Popular Garden Cress Varieties

 Cooking Cress

Culinary cress greens taste best when harvested young before they flower. Delicious raw or cooked, raw watercress provides the most benefit from vitamin C, isothiosianates, and other heat sensitive/water soluble nutrients. 

Watercress is primarily consumed fresh; however, dried watercress is available from botanical companies in cut and sifted, and powdered wild-crafted forms. Markets sell fresh spicy greens in small, hand-banded bundles. Similar to other greens, like spinach, cooking watercress takes a large quantity of leaves just to serve 3 or 4 people. As you know, greens can really cook down, which is why cress is more practical in certain types of recipes.

You'll find watercress in the well-known V8® Vegetable juice and as the star ingredient in classic French potage cressonnière - a cream of watercress and potato soup.  Watercress adds a gourmet touch to egg dishes, atop sandwiches, salads, and as a flavorful garnish to just about any entrée. 

When combined with its other volatile constituents pulegone, a naturally occurring compound found in watercress and many foods (including oregano, beans, tea, peppermint oil and pennyroyal oil), adds an unidentifiable hint of mint flavor and aroma giving watercress its own unique, peppery, distinctive flavor. Whether added to breakfast, lunch or dinner recipes, raw or cooked, the pungent flavors from watercress (or any culinary cress) will make your recipe a palate-pleasing winner.

Photographs: Nasturtium officinale W.T. Aiton - watercress courtesy of: NAOFRobert H. Mohlenbrock @ USDA-NRCS PLANTS Database / USDA NRCS. 1995. Northeast wetland flora: Field office guide to plant species. Watercress beds in Warnford, Hampshire England courtesy of Pterre, Wikipedia GNU Free Documentation License. All other photographs Copyright ©2010 Wind. All rights reserved.

References:

[1] USDA NRCS Plants Profile: Nasturtium officinale W.T. Aiton Watercress. Accessed Feb.4, 2010

[2] FAO Ecocrop Nasturtium officinale. Accessed Feb.4, 2010

[3] Yazdanparast R, Bahramikia S, Ardestani A., Nasturtium officinale reduces oxidative stress and enhances antioxidant capacity in hypercholesterolaemic rats. Chem Biol Interact, 2008 Apr 15; p172-3:176-84

Further Reading: Creasy Greens... Say WHAT? By Darius Van d'Rhys

Related Links:

Growing Watercress by National Gardening Association Editors

Watercress in the Garden by Trudy Kendrick and Dan Drost, Utah Cooperative Extension

About Diana Wind, RD   Diana is a registered dietitian with a passion for gardening and sustainable foods. She is a member of the Academy of Nutrition and Dietetics and the Garden Writers Association. Food from the garden fuels her enthusiasm for Culinary Arts and Nutritional Science. “I especially love gardening as part of a healthy lifestyle. Gardening engages us with nature, gives us health benefits from exercise, and rewards us with fresh, nutritious foods. To assess your food and garden activity level, visit https://www.choosemyplate.gov/SuperTracker/default.aspx or my blog: http://GardenCuizine.com. Happy and Healthy Gardening!"

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