Watercress

Watercress (Rorippa nasturtiumaquaticm [L.] Schinz & Thell.) is a popular cool-season salad vegetable. Like collards, broccoli, turnips and their relatives, watercress is a member of the Mustard Family (Cruciferae or Brassicaceae). The generic name is thought to be derived from rorippen, the ancient Saxon common name for watercress. This perennial plant has its natural distribution in Europe and western Asia, but has become naturalized extensively throughout the cool-temperate climatic areas of the world.

Portions of the plant commonly eaten are the upper 4 to 6 inches of the vegetative stems and associated leaves. Watercress gives a pungent flavor to salads, makes a novelty sandwich filling, is sometimes used as a flavoring in soups, and serves as an attractive garnish.

Watercress grows naturally in clear, cold, shallow, slow-moving creeks. It may grow either as a floating plant, become rooted in the bottom, or creep along wet stream margins.

Watercress grows well on rich, slightly acid to slightly alkaline garden soils (pH not lower than 6.0), for which ample irrigation is available. Plantings can be established readily by means of stem cuttings, or by raising plants from seeds.

Home gardeners may adopt either the trench or surface culture systems for watercress.

For those particularly fond of high quality watercress, the trench system of culture may be well worth the effort involved. In this system a trench is dug 2 feet deep and 2 to 3 feet wide. A 9-inch layer of well-rotted compost or manure is placed in the bottom of the trench and allowed to settle for about 2 weeks. Irrigate daily at the rate of 3 to 4 gallons of water per yard of trench length. At the end of the period, put 4 inches of good topsoil over the organic mass and press it down firmly.

The prepared trench may be planted either with seeds or stem cuttings. If seeds are used, the gardener will find them to be quite small about 150,000 per ounce and to have a rather low germination standard, about 40% to 50%. The trench should be marked off in a grid of 8-inch squares, and several seeds planted at each intersection in the grid.

Cover the seeds with about 1/16th inch of fine sand. Mist the planting frequently, so that it never dries out, and keep the trench dark by covering with some material that will exclude light, laid over a supporting framework.

After germination is complete, remove the opaque covering and thin the seedlings to 1 per intersection. Give the trench a good flooding after thinning.

If stem cuttings are to be used as planting stock, they may be collected from the wild. Or bunched watercress from the supermarket may be used. Plant one cutting at each intersection on the 8 x 8 inch grid, and water thoroughly.

With either starting method, keep the soil free from weeds by hand weeding until the watercress plants grow large enough to provide strong competition for them. Never allow the soil to dry out. The plants will benefit from being irrigated daily with a fine mist nozzle, except in rainy weather.

As soon as the plants have reached about 6 inches in height, pinch the leading shoot to encourage branching. The plants should not be permitted to flower. As soon as signs of flower buds are observed, cut the plants back.

It takes 60 to 70 days for watercress to reach harvest maturity from seeds, somewhat less from cuttings. Hence, in mild climatic areas it may be a good plan to start a succession of trench cultures about a month apart to assure continuity of quality harvests.

In the surface culture system, prepare the soil with a high level of organic matter from manure or compost. A bed of several short rows will be easier to handle than a single long row. Rows in the bed may be placed 12 to 18 inches apart. Sow the seeds very shallowly at the rate of 0.5 ounce per 100 feet of row. Even distribution of the seeds will be readily achieved if they are first mixed with a very fine-textured dry sand.

The planting should be kept wet throughout germination, emergence, and seedling establishment. As soon as the first true leaves appear, the seedlings may be thinned to stand 8 to 10 inches apart in the row. Maintain constantly high soil moisture levels for best results.

An alternative to direct seeding in the garden is starting the seed in small peat pots under a mist propagation system, provided you have a greenhouse equipped for this. Sow several seeds in each pot, thinning to one seedling after the first true leaves have appeared.

Well-started seedlings may be transplanted to the prepared bed in the garden, pot and all, or possibly maintained under mist in the greenhouse for nearly year-around harvest. Due to leaching effects of the mist, occasional application of liquid fertilizer is advised to maintain vigorous growth.

Apart from the above, cultural practices for surface culture are similar to those for the trench system.

In harvesting watercress, take a sharp knife and cut about 6 inches of the leading shoots or side shoots. Tie the cut pieces into bunches and trim the butt ends so the finished bunch is about 4 inches long. The harvested bunches may be kept in water, or possibly in plastic wrapping in the refrigerator for limited periods. The home gardener can expect to harvest one bunch of watercress per foot of row.