How to Plant, Grow, and Care for Watercress

Who can resist the hot, peppery taste of watercress in a salad, a sandwich, or even garnishing a burger, but did you know that watercress is very easy to grow yourself?  Read on to learn how to grow watercress at home in your own garden.

As a water-loving perennial, it’s often assumed that watercress can only be grown in fresh flowing water. While this is true, you’ll be happy to learn that recreating these growing conditions using containers is straightforward. You can even grow watercress on a sunny windowsill if you follow our tips!

Watercress has been cultivated since Roman and Greek times, and there are good reasons for its long success. Those small fresh leaves are packed full of vitamins A and C, iron, calcium, and folic acid, making watercress a nutritional powerhouse. It’s not just for salad mixes, either.  Add a handful of leaves to smoothies for a healthy vitamin boost, or try your hand at making watercress soup or pesto sauce to add to pasta. Either way, this incredibly versatile leaf is going to taste delicious. 

What is Watercress?

Watercress, also known as garden cress, comes from the cabbage or mustard family Brassicaceae. With the botanical name Nasturtium officinale, it would be easy to confuse watercress with the land-grown, colorful nasturtium ornamental flowering plant, Tropaeolum majus. To add even more confusion, both plants are edible and have a strong peppery flavor, but they are not related botanically.

Native Area

Watercress is native to Europe and Asia and is naturalized across North America growing in streams, springs, slow-moving rivers, and marshland. As a semi-aquatic herb, watercress thrives in permanently wet conditions, either partially submerged or grown in soil regularly refreshed with clean, clear water. Watercress cannot grow in a stagnant environment.

Characteristics

Watercress has a dense, sprawling growth habit, propagating freely from leaf nodes which is why you sometimes see fine hair-like white roots on your bagged watercress salad from the supermarket. Leaves are mid-green, alternate, pinnately compound ranging between three to nine leaflets growing on hollow stems.

Clusters of four-petalled white flowers are borne on dark green/brown stalks protruding slightly above the carpet of leaves and are a magnet to water insects, hoverflies, and bees. Flower production is stimulated by day length and tends to occur in mid to late summer. 

Seed pods are similar in appearance to other brassica family varieties: long, thin, and upright, turning brown when ready to harvest. Pods remain elevated above the water, bursting when ripe, falling close to the parent, and usually germinating within a week, providing continuous crop throughout the season. Seeds are tiny, oval, brown specks that are best broad-sown. Each pod contains 20+ seeds, and each cluster of flowers has around 20 seed pods. 

Watercress has both basal roots to secure it to the location and advantageous roots that float and assist in progressing colonization.

Watercress has a vigorous growth rate, allowing harvests in as little as four to seven weeks. Treated as a cut-and-come-again salad, watercress rewards you with continuous lush growth from spring to late fall. Leaves become bitter and unpalatable after flowering, so frequent harvesting will keep your watercress producing new leaves for longer.

All parts of the watercress, including the flowers and roots, are edible, but the latter parts tend to be bitter. Watercress is grown primarily for its tasty leaves, which are best consumed raw to get the most nutritional value. Leaves can also be cooked in soups and stir-fries or wilted like spinach.

Planting

Plant shop-bought watercress outdoors from March if no harsh frosts are forecast. Young plants may suffer from a sudden change in temperature so it’s best to acclimatize them over a few days. If growing in containers, keep indoors until the first frost-free date.

Sow watercress seeds outdoors from spring when average daily temperatures are between 50-60°F (10-16°C) or indoors and plant outside once they have become established. Seeds require this temperature range to successfully germinate.

If using store-bought transplants in garden ponds, simply place watercress into aquatic pots filled with compost or soilless potting mix and topped with gravel to prevent the growing media from floating away. Sow seed directly along the edges of ponds as long as the soil is saturated, as they grow naturally in that sort of environment. 

No access to a garden pond? No problem. Grow in containers outside or even on a windowsill. Grow transplants or sow watercress seeds on the surface of the soil and place the pot into a deep saucer filled with water. Keep the saucer topped up at all times using rainwater whenever possible. Place the container in a bright sunny location and watch your watercress grow! Although watercress is a perennial, when growing in containers, it should be treated as an annual.

Watercress will not tolerate stagnant conditions which encourage bacterial growth. To avoid this flush your pots at least twice a week simply by removing the saucer and watering the container with fresh water allowing the excess to drain away. Do this a couple of times and return to the saucer topping it up with clean water to keep the soil moist.

How to Grow

Watercress is self-sufficient with few issues when grown in the correct habitat. Follow the tips below to learn how to grow watercress!

Light

Grow watercress in full sun to part shade. Growing watercress in a more natural environment can be done in full sun, whereas container-grown watercress will benefit from some shade to prevent containers from drying out.

Water

Those grown in a natural habitat like a stream or pond do not require additional irrigation.  Keep container-grown watercress wet at all times by standing pots in deep dishes of water and regularly top up when levels drop. Flush containers with fresh water twice a week to prevent them from becoming stagnant and developing bacteria.

Constant moisture is an absolute necessity; you can place a shallow container in a larger container with extra water in it to ensure that the growing media has enough water retention, provided that you regularly change out any standing water with fresh.

Soil

Watercress is not fussy on soil type, growing well in chalky, sandy, silt, clay, loam, and even gravel, as long as the pH remains between 6.5 to 7.5. A pH of 7.2 is perfect. Soil aeration is key to healthy watercress, normally catered for in slow-moving waterways but easily replicated in containers through regular irrigation with clean water. It’s important to keep the soil moist at all times.

Temperature

USDA hardiness zones 3 to 11 are suitable locations to grow watercress although it is really a cool-season crop. As temperatures rise in summer, they will begin to flower and overall growth slows down. Watercress is susceptible to spring and winter frost damage. Move containers indoors when temperatures begin to drop to lengthen harvests.

Fertilizing

Those cultivated in containers may show signs of potassium, iron, and phosphorus deficiency demonstrated by leaf discoloration and general lackluster appearance. Provide a nutrient boost with a complete soluble fertilizer or seaweed feed added to the water once every few weeks.  

Maintenance

Generally, pruning is not necessary for growing watercress, although they benefit from regular snipping to encourage new lush growth for continual harvest.

Propagation

Propagate watercress by seed or plant division. Watercress seeds are very small so it is best to broad sow where you want it to grow in the ground or directly into containers. Sow the seed thinly on the soil surface and leave it in a sunny location with temperatures around 50-60°F to stimulate germination which usually takes about 7-14 days. 

Dividing established herbs is an excellent way to propagate as they will establish quickly and you’ll harvest leaves in no time at all. Simply choose a fresh young area and, using a knife or hand trowel, cut away the amount required, making sure to include a good amount of root.  Plant the division into its new location outside or in a container with wet soil or compost. Stem cuttings are also viable options.

An alternative way to propagate watercress is using leaves from store-bought salad bags.  Place the branched leaves with the little hair-like roots, into a shallow tray of water.  In just a few days the roots will grow new watercress. Pot rooted cuttings in the same way as divisions. 

Harvesting

Now for the best bit! Learn how to harvest and store your homegrown watercress to get maximum enjoyment.

Harvest watercress four to seven weeks after sowing. Look out for lots of new leafy growth on stems that are around four to five inches long and harvest as a cut-and-come-again salad. When cutting stems back make sure you leave some side shoots and leaves at the base to allow it to re-sprout. 

Storage

Once harvested, store your freshly cut watercress leaves in a bag in the refrigerator for up to a week. Use watercress fresh for the best flavor.

Common Problems

Despite being an easy herb to care for there are a few issues to look out for when growing watercress. Check them out below.

Growing Problems

Drought and stagnant growing conditions are the main growing problems associated with watercress. When planting outside in a water feature, the water must be constantly refreshed, providing oxygen to your watercress. 

Top up container-grown watercress daily and flush at least twice a week to prevent the water and soil from becoming stagnant. Keep the planting area moist at all times to ensure vigorous growth.

Watercress can become invasive if left to their own devices, blocking drains and causing local flooding. If your crop becomes too big to handle, simply weed it back to a manageable size.

Pests 

Slugs and snails can be a problem when growing watercress. They love damp conditions and enjoy feasting on the constant supply of new shoots. Handpicking and removing hiding spots such as damp wood, logs, and debris will help reduce numbers. Spreading an organic slug and snail bait on one side of the garden may distract them.

Whiteflies can rapidly colonize watercress. The safest and easiest way to keep them under control is to squish them by hand or use a soft jet of water to remove them. Treat Spider mites in a similar way. If this doesn’t work, try using an organic insecticidal soap or neem oil.

Diseases

Densely sown seedlings can suffer from damping off. This can be caused by pathogens in the soil and seed trays or garden soil becoming stagnant. To minimize the risk, clean containers and seed trays thoroughly before use and always use fresh compost. Watercress loves a damp wet environment as long as water can drain away freely and is replenished frequently. 

Crook rot is a fungal disease spread by spores, entering the root cells and spreading to stems and leaves. Symptoms include malformation of all parts of the watercress. Leaves and stems look swollen and stunted. There are no recommended chemicals or organic solutions to treat this disease. Container-grown crops can be flushed repeatedly over a few days to purge any spores contained within the soil, but if signs of malformation continue, dispose of it before it develops a new crop of spores.

Frequently Asked Questions