Watercress is an easy-to-grow food crop.
Watercress (Nasturtium officinale) is an aquatic plant that thrives with its roots in water and its leaves in the sun. It is grown as a food crop for its peppery leaves, which are used in salads and soups. The BBC website reports that a study published in the American Journal of Clinical Nutrition found that eating watercress reduced DNA damage in white blood cells and may even reduce the risk of cancer.
Location
The ideal location for growing watercress is a gently-sloping bed on the inside bend of a stream, but watercress can also be grown in a purpose dug bed or container. Prepare a bed by lining a 6-inch deep basin with waterproof polythene sheeting. Watercress can also be grown in an existing water feature.
Temperature
Watercress will grow as a perennial plant in U.S. Department of Agriculture Plant Hardiness Map Zones 5 and above.
Light
Watercress plants grow fastest in bright light and will grow in full sun provided they are not allowed to dry out.
Water
Plant stream-grown watercress in water about an inch deep. Container or bed-grown plants need water about 2 inches above the soil line. Keep watercress pots on a dish of water to maintain the water level, but change the water regularly.
Soil
Use standard potting compost mixed with perlite for bed and container plants. For beds a 2-inch layer of compost is sufficient.
Fertilizer
Stream-grown watercress obtains its nutrients from naturally occurring minerals in the water. Container or bed-grown plants can be fertilized with 1 cup of standard gardening fertilizer per 25 feet of soil surface. Fertilize after harvesting the crop.
Propagation
Sow watercress seeds thinly in very moist compost at a depth of 1/4 inch. Once the seeds germinate, after five days, raise the water level gradually until it is 2 inches above the soil line. Watercress can also be grown from stem cuttings laid on top of the compost with 6 inches between plants.
Harvesting
Harvest watercress once the plants are 12 to 15 inches above the water's surface. Cut off the stems 4 inches above the water line to allow side shoots to grow and produce the next crop.
Tags: inches above, also grown, above soil, above soil line, above water, bed-grown plants, Container bed-grown