Watercress: Water-loving salad vegetable
A delicious and popular salad vegetable,is an interesting crop for the ambitious gardener who wants to try his hand at something really different.
Watercress /Nasturtium officinale) is a hardy annual which is grown for its leaves, usually eaten raw in salads. The leaves have a rather pungent and peppery flavour, and they are an excellent source of winter vitamins. They also contain a fair amount of protein, making them a particularly good salad vegetable.
Although recognized as a useful and delicious vegetable for quite a long time, watercress has been a cultivated crop for less than a hundred years. Previously it was simply gathered from shallow streams, where it grows naturally. You can still find watercress growing in the wild, but you will be assured of better crops if you are willing to take the time and trouble to grow your own.
There are two types of watercress— green and brown. Green watercress is best for summer crops. It remains green until autumn, but is damaged by frost. Brown watercress (N. microphyllum x officinale), on the other hand, will bear some degree of frost, thus making it ideal for winter and spring crops. Its leaves turn purplish-brown in autumn, but they are still good to eat. Both varieties ofare cultivated in the same way.
As the name implies, watercress needs a great deal of water to grow. The roots must be in water, but the plant need not be totally immersed. However, you must be extremely careful about the water you plant it in, as a polluted water source will produce inedible, useless crops. Never plant watercress in a garden pool, which can be stagnant; the plants will not survive in stagnant water.
If you are lucky enough to have a clean natural stream in or near your garden, you can sow your seed along the bank, about 15 cm (6”) above the water line. The site should have partial shade, if possible.
Most gardeners will not have access to a stream, so it then becomes necessary to prepare a special bed in which to grow watercress. Select a site which is in partial shade, but is free from overhanging trees, as falling leaves or blossoms will not do your cress any good. Despite the old myth that you must have permanently running water to grow good watercress, this is not so, but the site must be always moist, and you must be willing to water the bed daily. For this reason, a site close to a garden standpipe or within easy reach of a hose is essential.
To prepare a bed, usually done in early spring, mark out a site about 1 sq m (1 sq yd) in area, which will be sufficient space to supply the average family with watercress. Dig thevery deeply, and at the same time mix in sufficient peat or other organic material to make the ground rich and moisture-retentive, but not waterlogged. The surface of the bed should be about 2.5 cm (1”) or so below the surface of the surrounding soil.
After the bed is dug, firm the surface and rake it over to make it level. Then flood it with fresh water, filling it up to the level of the surrounding soil. When the water has drained away, you are ready to sow your seed. Start off with a mid-spring sowing of the green type— you should be able to obtain the seed from a good garden centre or nursery. Sow the seed thinly broadcast; do not cover it with soil. When the weather is warm, germination is quick and you should be able to start taking single leaves from plants within about two or three weeks of sowing. As the plants grow and get well established, you can either take off individual sprigs or, in the early stages, remove plants completely so that the remainder have more room in which to grow.
Once a bed is started, it will require frequent watering to keep it growing. A trickle irrigation system is a particularly good idea, especially in a dry summer, otherwise you will have to water daily, preferably by garden hose, using a gentle pressure, and flooding the bed each time. Be sure that the water continues to drain, as the plants will not survive in a waterlogged or stagnant bed. Keep a look out for anyand remove them. Since watercress grows naturally in water, trickle irrigation will give the best results, if you do not have a stream in the garden.
If you cannot obtain watercress seed, then you can use watercress from the greengrocer asfor planting. Obtain the shoots as newly cut as possible. They may already have some roots; if not, stand them in a glass of water at atmospheric temperature and they will root in a day or two. To plant, strip the leaves from the bottom half of the stem, and then place the cuttings in the bed, about 5 cm (2”) apart. Bury them in the soil to a depth of 4 cm. Be sure to keep the bed completely shaded until the cuttings are established. Rooting and establishment will be more certain under warm weather conditions. Brown watercress for winter and spring use must be grown from cuttings, as seed is very rarely available. Plant your bed with these cuttings in late summer, and you should enjoy supplies throughout the winter and spring.
Be sure to protect the green watercress bed with a frame in frosty weather, or your plants will be frozen and die. This cress tends to sink below the surface of the water in which it is growing in cold weather, as the water temperature is warmer than the air, but it can still be cut.
Watercress of both types should always be cut with scissors, never pulled, as the whole plant is likely to come up, rather than the leaves or few sprigs required. Do not cut too far down the stem, which will then continue to produce new shoots for cutting.
Watercress beds can be kept in crop for several years in succession, but the plants tend to deteriorate from constant cutting and decrease of food supply. Also, the drainage deteriorates, so it is better to prepare a new bed in a different part of the garden every two or three years.
If you do not wish to go to the work of preparing a special bed, watercress can sometimes be grown in shallow pots or ciay pans standing in containers of fresh water. Fill the pots with a good quality, moisture-retentive pottingto a depth of 7.5 cm (3”), and sow the seed broadcast. Keep the containers in a shady spot on balcony or patio, or on a shady windowsill, and remember to keep them supplied with plenty of fresh water.