How to Grow and Care for Watercress

Watercress (Nasturtium officinale) is a water-loving perennial herb that typically grows along stream banks and near sources of water. It is a member of the mustard family (Brassicaceae), which also includes collard greens, kale, turnips, and radishes. Watercress is widely cultivated around the world. Its leaves and young stems add a peppery bite to any salad, soup, or sandwich.

As long as you provide it with plenty of moisture, it is easy to grow watercress in an outdoor garden bed or container or indoors year-round. Plant watercress in early spring and harvest it before the onset of hot summer weather.

Watercress is toxic to pets.

How to Plant Watercress

When to Plant

Plant watercress early in the spring. Direct sow when soil temperatures are between 50 and 60 degrees F or start the seeds indoors three to four weeks before your average last frost date. Never let the soil dry out, as watercress requires wet soil for best germination. Seeds germinate in 7 to 14 days.

Sow greens every couple of weeks to ensure a continuous supply of young plants

Selecting a Planting Site

Choose a spot with consistently wet soil and full sun exposure.

Spacing, Depth, and Support

Plant watercress seeds just below the soil surface, 1/4 inch deep, spacing seeds 1 to 2 inches apart.

Thin seedlings to 6 inches apart. Watercress does not need any support.

Watercress Plant Care

Light

Watercress grows best in a location with full sun to partial shade. If grown indoors, make sure to place the container in a spot that gets at least four hours of sunlight per day.

Soil

Watercress is not very fussy about soil types as long as it retains water well and it tolerates a wide pH range. Soil rich in organic matter is best.

Water

Whether you're growing the plant indoors or outdoors, it's important to keep the soil moist at all times.

The amount of time between waterings will vary based on factors such as rainfall frequency and humidity. The best way to check is to use a soil moisture meter, or simply by manually feeling the soil with your finger.

Temperature and Humidity

Watercress thrives in cool, wet conditions with daytime temperatures between 60 and 70 degrees F. In temperatures above 85 degrees F, its growth slows and the flavor becomes bitter.

Although watercress is a perennial that withstands light frosts, in areas with cold winters, it is best grown as an annual or brought indoors for the winter.

Fertilizer

If your watercress plant has yellowing leaves or stems, or scorching on older leaves, this could be a sign of nutrient deficiencies. Otherwise, watercress does not have high nutrient needs. To boost its growth, apply an organic fertilizer, such as a kelp-based fertilizer, every two to three weeks.

Types of Watercress

In addition to watercress, two other types of cress are grown for culinary purposes:

• Upland cress (Barbarea verna), also called creasy greens in the South, is an annual that is similar to watercress. It is slow to start but has the advantage of being slow to bolt. It can be harvested as micro greens, baby greens, or in its mature stage. 50 days to maturity
• Curled cress (Lepidium sativum), also known as garden cress, is an old variety native to the Middle East and Iran. It grows up to 1 foot in height but is most commonly harvested at the seedling stage when the ruffled, peppery leaves are the most tender. 30 days to maturity

Harvesting Watercress

All parts of the watercress plant are edible—even the flowers—but the leaves and stems are the most commonly desired. There are many stages at which watercress can be harvested.

Watercress microgreens will be ready to harvest within 10 to 15 days. When they are about two inches tall, use scissors to cut the greens just above the soil. Rinse the watercress microgreens in water before consuming them.

Watercress leaves and stems will be ready to harvest around three weeks after the sprouts first emerge. Harvest watercress at any time once the plant reaches maturity, which is once the stems are at least six inches tall. Using scissors, carefully cut the stem close to the base. To ensure the plant continues to grow, never harvest more than one-third of a plant's leaves.

Once watercress goes into flower in the warmer summer months, the leaves will become bitter, so harvest as much of the plant as possible before then.

How to Grow Watercress in Pots

Growing watercress in a pot makes it easier to simulate the saturated conditions of a stream than growing it in garden soil. Choose a pot at least six inches wide with large drainage holes.

Use a soilless potting mix that is mixed with peat to increase water retention. Keep the potting mix moist by placing the pot in a saucer filled with water.

As watercress is mostly grown as an annual, repotting won't be necessary.

Pruning

Harvesting leaves from your watercress plant also doubles as pruning, and will encourage the plant to produce new growth. Of course, you should also prune away any yellowing, dead, or damaged leaves if you see them. Using a clean pair of pruning shears, cut the damaged stem away at its base.

To keep watercress from going into its flowering stage, use your pruning shears to remove any buds before they blossom, removing them just below the flower head.

Propagating Watercress

Watercress is easily propagated from stem cuttings by using the water method. The best time to do this is in the spring.

1. Find a healthy stem on a mature plant to use as the cutting.
2. Remove the leaves from the watercress stem.
3. Place the watercress stem in a small jar with water.
4. Wait for new roots to emerge and new leaves to start growing. This step generally takes a few days.
5. To plant, follow the spacing and planting recommendations for watercress above.

Common Pests and Plant Diseases

Watercress has no major pest or disease problems. It is susceptible to common insect problems including whiteflies, spider mites, and garden snails. A strong spray of water helps to control insects before they become an infestation.

• Is watercress a perennial or annual?

  Watercress is botanically a perennial plant but home gardeners commonly grow it as an annual.

• Is watercress an invasive plant?

  Watercress is not a native species, it has naturalized throughout North America. It is considered a noxious weed or invasive plant in some regions.

• Should I let my watercress flower?

  Although the flowers are edible, once the plant starts to flower, the leaves of watercress become less tasty so it is usually recommended not to let it flower and stop harvesting the leaves when it does.

From: thespruce