Cress (Lepidium sativum) & Watercress (Nasturtium officinale)
Cress (sometimes called garden cress, garden pepper cress, pepperwort, or pepper grass) is a leafy annual herb from the Brassica family. It is harvested when immature, around one to two weeks after germination, but will grow to a height of around 60cm (24”) if left undisturbed, and then form racemes of white flowers followed by small seedpods. The leaves and stems of young plants are crisp and succulent and high in water content, and the flavour is a bit spicy, similar to the closely related mustard greens. This makes for a surprisingly lively salad green.
Wrinkled cress or “curled” cress has leaves that are serrated and frilly, like a miniature and more succulent version of parsley. It adds more texture and bite to salads and sandwiches, but it is also harvested at an immature stage. Both types are grown in large-scale agriculture, and both are very easy for the home gardener. Upland cress (Barbarea verna) eventually grows out jagged, serrated leaves, but it is usually harvested while the leaves are still small and rounded. This variety will survive with less water than the others, but still prefers moist soil.
Watercress has the same succulent texture as its garden cousins, but grows as an aquatic perennial plant, forming dense mats of foliage at the ends of hollow, sap-filled stalks. Its leaves are pale green and round, about 10-15mm (1/3 — ½”) across. Watercress should be grown in wet (as opposed to damp) soil, preferably along the margins of running water. Watercress will also produce small racemes of white flowers, but will keep growing after going to seed. Once flowering is underway, the leaves of watercress become bitter.
Watercress’ genus name, Nasturtium comes from the Latin nasus tortus or “twisted nose,” and is thought to refer to the pungent flavour of the plant. Do not confuse this genus with the garden flower known as nasturtium (Tropaeolum majus) — the flower earned its common name after watercress as both plants produce a kind of oil that is chemically similar. It’s worth mentioning here that the flower nasturtiums are also edible, and their leaves and flowers both have flavour and texture reminiscent of cress and watercress. Nasturtium microgreens are incredibly piquant, with a sharp pepper flavour. The two types of plants, however, are unrelated. Confusingly, the flower nasturtium is sometimes referred to as Indian cress.
Watercress is native to Europe, but it can now be found growing wild along slow moving waterways in North America. Watercress appears to have been one of the earliest cultivated leaf vegetables — the ancient Greeks and Romans often used it as an inexpensive alternative to black pepper, which had to be imported from India. Land-loving garden cress originated in ancient Persia.
Early herbalists were well familiar with watercress, and noted its medicinal qualities. Of watercress, Nicholas Culpeper wrote:
It is more powerful against the scurvy, and to cleanse the blood and humours, than brooklime, and serves in all the other uses in which brooklime is available; as to break the stone, and provoke urine and women’s courses. It is also good for them when troubled with the green sickness, and it is a certain restorative of their lost colour if they use it in the following manner: chop and boil them in the broth of meat, and eat them for a month together, morning, noon, and night. The decoction thereof cleanseth ulcers by washing therewith; the leaves bruised, or the juice, is good to be applied to the face or other parts troubled with freckles, pimples, spots, or the like, at night, and washed away in the morning. The juice mixed with vinegar, and the forepart of the head bathed therewith, is very good for those that are dull and drowsy, or have the lethargy. Water-cress pottage is a good remedy to cleanse the blood in the spring, and help head-achs, and consume the gross humours winter has left behind; those who would live in health, may make use of this: if any fancy not pottage, they may eat the herb as a sallad.
Both common forms (and their handful of wild cousins) are high in vitamins A and C, as well as iron, calcium, and folic acid. Watercress, particularly, is thought to contain significantly high levels of antioxidants, and many people believe that it has cancer-suppressing properties. It is notably high in iodine and has been used to treat hypothyroid conditions.
How to Grow Cress:
Difficulty: All cress types are very easy to grow, but watercress requires uniquely wet growing conditions. If its needs can be met, it’s very easy. Garden cress is well suited to containers. Remember, it’s usually harvested at a very young age, so it can even be grown indoors, similar to the way you might grow sprouts or microgreens.
Timing: Grown indoors for sprouts, cress can be sown at any time of year providing that a brightly lit area is available. In the garden, sow seeds in spring, and water them in with a kelp-based fertilizer. Watercress can be sown in pans of water or in constantly wet soil. If you have access to a slow moving brook, sow watercress seeds (or transplant store-bought) along the margin of the brook, using small stones to hold plants in place. Keep leaves above the surface of the water. Sow again September 1st. All types should overwinter in this area.
Sowing: Barely cover garden cress seeds. Keep very moist.
Soil: All types prefer fertile, humus-rich soil with a pH around 7.0 in full sun or partial shade.
Growing: If you want to grow watercress indoors for sprouts, remember that there are few available nutrients in the water to help the young plants grow. Apply liquid fertilizer and change the water as often as possible. When plants are 5cm (3”) tall, thin and eat the thinnings.
Harvest: At 15cm (6”) tall, harvest garden cress with scissors — it will grow back at least once. Start a new row or pot just before you harvest the first one, and repeat for the longest harvest.
Storage: Store in the refrigerator, but not for more than two days.
Seed info: Seeds germinate at 10-15°C (50-60°F), usually within 7 days.
Pests & Disease: Slugs can attack outdoor garden cress, but this can be prevented by growing in containers that are kept off the ground.