Watercress

Watercress is a semi-aquatic herb that produces some of the most nutritious edible greens available, packed with vitamins, minerals, and peppery mustard flavor. In nature it grows in clean, cool, running water, but it can also be cultivated in consistently wet garden soil, containers kept in water trays, or hydroponic systems. Space plants 15cm apart in partial shade with rich, moist to wet soil.

The ideal growing conditions are cool temperatures (10-20°C), partial shade, and constant moisture. In garden beds, keep soil perpetually wet—this is one herb you cannot overwater. Stand containers in deep saucers kept topped up with water. For best results, simulate stream conditions with a shallow water garden or recirculating hydroponic system with cool, clean water.

Watercress grows quickly in cool weather, bolting rapidly when temperatures exceed 25°C. For the longest harvest season, grow in spring and autumn, using shade cloth in summer to extend production. Stems root at nodes where they contact water or wet soil, making watercress remarkably easy to propagate. A few supermarket watercress sprigs placed in water will root within a week and provide the start of a productive patch.

Watercress (Nasturtium officinale) is native to Europe and western Asia, where it has grown wild along streams, springs, and riverbanks since prehistoric times. Archaeological evidence suggests that humans have consumed watercress for thousands of years, and it is considered one of the oldest known leaf vegetables eaten by people. Ancient Persians, Greeks, and Romans all valued watercress highly — both as a food and as a medicine. The Greek general Xenophon made his soldiers eat watercress to build vigor, and the Roman naturalist Pliny the Elder documented over forty medicinal uses for the plant.

In medieval Europe, watercress grew abundantly near monasteries and was cultivated by monks who recognized its nutritional and healing properties. It was one of the few fresh greens available in early spring, providing essential vitamins after the long winter months of preserved and dried foods. By the 16th century, herbalists across England and continental Europe prescribed watercress for ailments ranging from toothaches to tuberculosis, and the plant featured prominently in the pharmacopoeias of the era.

The first commercial watercress farm was established in Erfurt, Germany in 1750, and the practice spread quickly to England, where the chalky spring-fed streams of Hampshire and Dorset proved ideal. By the 1800s, watercress cultivation was a thriving industry in southern England, with special 'watercress trains' running from Hampshire to London's Covent Garden market each morning. In Victorian London, watercress became the breakfast of the working poor — cheap, nutritious bunches were sold by thousands of street vendors, many of them children, from dawn each day.

Watercress traveled to the Americas, Australia, and New Zealand with European settlers, quickly naturalizing in clean streams across temperate regions worldwide. Today it is grown commercially in the UK, France, the United States, Portugal, and Brazil, with both traditional stream-bed farms and modern hydroponic operations supplying year-round demand. Its recent recognition as the most nutrient-dense vegetable by the CDC has sparked renewed global interest in this ancient green.

Grow in rich, organic soil kept perpetually wet or in clean, cool water. Ideal pH is 6.5-7.5. In soil culture, amend heavily with compost and keep waterlogged. For hydroponic growing, use a diluted balanced nutrient solution in cool water (15-18°C). Feed soil-grown watercress monthly with balanced liquid fertilizer. The high growth rate demands consistent nutrition. In water culture, change water regularly to prevent stagnation.

Begin harvesting watercress just 3-4 weeks after planting, when stems reach 10-15cm long. Cut stems above the waterline with scissors, and the plants will regrow rapidly for multiple harvests. The youngest leaves and stem tips have the best flavor—older, larger leaves become tougher and more peppery. Harvest before flowering for the mildest taste. In cool weather, watercress can be cut every 2-3 weeks. The flowers are also edible with a peppery kick.

Fresh watercress is highly perishable and best used within 2-3 days. Store with stems in a glass of cold water in the refrigerator, loosely covered with a plastic bag. Change water daily. Do not wash until ready to use. Watercress does not dry well, as the peppery flavor is lost. Freeze pureed watercress in ice cube trays for adding to soups and sauces. Make watercress pesto or butter for longer storage. Watercress soup freezes well.

Watercress is a nutritional powerhouse with a distinctive peppery, mustard-like bite. Classic in English watercress sandwiches with butter on white bread. Makes elegant watercress soup (hot or cold). Add to salads for a peppery kick, especially with citrus, goat cheese, and walnuts. Blend into pesto, green sauces, and smoothies. Wilt lightly as a side dish like spinach. Garnish steaks, grilled fish, and roasted beets. Pairs with eggs, potatoes, and smoked salmon.