Watercress: growth, care & benefits
Watercress is full of benefits for human health and it is often used to refine and decorate dishes. Learn everything you need to know about growing watercress here.
Watercress (Nasturtium), or yellowcress, is a species of aquatic herbs, which is often used to enrich certain dishes. It is closely related to garden cress (Lepidum sativum). While watercress remains rather unknown to many, its close relative garden cress enjoys a little more popularity. In this article, we will introduce you to watercress. Hopefully you will be persuaded to grow this aromatic and spicy herb at home.
Watercress: origin & characteristics
Despite the similarity in their names, watercress and garden cress are not as closely related as one might think. What they do have in common is that they both belong to the cruciferous family (Brassicaceae). Plants from this family can be easily recognised by their four cruciform petals. This is pretty much all that watercress and garden cress have in common other than their pungent and spicy taste.
As a wild herb along streams and springs, watercress was once widespread in Europe. It was commonly used as a tasty snack for in-between meals on long walks or hikes, especially among the lovers of nature. Today, this herb, which is sensitive to pollution, is not as common anymore. It can still be found in some areas all over the world.
The plant needs a lot of moisture and grows in the shallow water of rivers and lake banks. Therefore, it is an aquatic plant. The green stems with the fleshy leaves float in the water. You can spot watercress by its leaves that protrude from the water. The plant retains its colour even in winter, which is why it is often the only fresh green vegetable on the plate, especially during the colder seasons.
The most popular watercress varieties
The genus of watercress (Nasturtium) includes two species native to Europe. Watercress is commonly referred to as the true watercress (Nasturtium officinale). This species is large, and its stems can grow up to 90 centimetres long. One form of this species is the red watercress (Nasturtium officinale f. rubrum) which, as the name suggests, can be identified by its bright red leaves. Smaller and more compact is the onerow yellowcress (Nasturtium microphyllum). The infertile cross between the two species, the brown watercress (Nasturtium x sterile), also occurs in nature. Its leaves have a bronze-like colouring during winter.
In addition to the watercress species, there are various other cultivars on the market.
Here is a brief overview:
- Watercress (Nasturtium officinale): characteristic with its large growth habit.
- Red watercress (Nasturtium officinale f. rubrum): one of the forms of watercress, can be recognised by its vibrant red leaves.
- Onerow yellowcress (Nasturtium microphyllum): compact growth habit, small-leaved.
- Brown watercress (Nasturtium x sterile): infertile cross between watercress and onerow yellowcress.
Even though watercress is of little agricultural importance nowadays, it can easily be found on the market as a plant or a seed. You can find watercress in your local garden centre or a hardware store with a gardening section. Some nurseries in your area might even have a larger selection of various watercress plants, so you can pick which one you would like to grow at home. Make sure to check the quality and health of the plant before purchase.
Watercress was once cultivated on a large scale by farmers. Cultivation of watercress is somewhat cumbersome, as the plant requires constant fresh water. Nevertheless, watercress can also be grown in your own garden and even on your balcony.
When and where to plant watercress?
The most important thing for growing watercress at home is, of course, water. If you have a stream in your garden, you are in luck, because you have the natural habitat of watercress right at your doorstep. Otherwise, you should try to get as close as possible to the natural habitat. This can be done, for example, by digging a moat, but also by growing watercress in pots. The main thing is that the plant always has clear, cold and oxygen-rich water available to it.
If all of the above is not possible for you, the moisture-loving plant can even be grown in damp places in the garden.
Watercress prefers sunny to semi-shady conditions, but the plant does not enjoy full and direct sunlight very much. Waters that the plant tends to occupy in nature are usually located in cool valleys and are sheltered from the sun.
When to plant watercress depends on the type of planting. You can sow the aromatic plant either around March or in early August. However, it is easier to plant cuttings, which you can do in summer.
Planting watercress in summary:
- Cultivation in and around water, in pot culture or in very humid places
- Sunny to semi-shady location, no blazing sun
- Sowing in March or August
- Propagation of cuttings in summer
How to grow watercress: instructions for growing watercress
Before growing, you should first look for a suitable location in the garden. Ideally, this would be an existing watercourse such as a stream or a pond with water circulation. If neither of these is available, you can create a water-filled ditch to grow your watercress – but that does require a lot of work. If you choose to go through with this, make sure to have a sufficient inflow and outflow of water.
It is much easier to cultivate watercress in a pot. To do this, place the young watercress in some type of planting device, preferably in the shape of a bowl. Next, place the watercress in a larger container, which you fill up with water until the soil in the bowl is about one centimetre under water. This way the watercress always grows in water. However, you must change the water every two days so that it always remains fresh and cool and also contains sufficient oxygen.
If the location is damp and shady, you can even grow watercress without water. Just keep in mind that watercress should never be allowed to dry out completely.
Whether in a pot or at the edge of a watercourse, sowing or growing is done without much water, but with sufficient moisture. Only when the cuttings are rooted, or when the seedlings have reached a sufficient size, are they replanted or placed in water. However, the tips of the plant should still stick out of the water.
A mixture of garden soil, sand and some compost is suitable as a substrate. Depending on the location, however, this mixture needs to be adapted. In a pond, for example, you should not add any compost, as algae can easily get into it. In the garden bed and in the pot, humus-rich soil with a nice portion of compost is recommended. While sand ensures aeration in a pot with water, it is better to leave it out in the garden bed, otherwise the water will seep away too quickly.
How to plant watercress in summary:
- Growing watercress in a pond: garden or pond soil with some sand
- Growing watercress in the garden bed: garden soil with a portion of compost
- Growing watercress in pots: garden soil with about 30% sand and a portion of compost
To grow your own watercress, the plant needs to be cared for well after planting. Luckily, watercress plant care is pretty easy. Once watercress has become an inhabitant of your pond or stream, all you really need to do is harvest it. Because the plant is perennial and reproduces well under the right conditions, you do not need to worry about the survival of your watercress.
When growing watercress in pots with water, looking after the herb requires a little more effort. It is important that you change the water every two days, otherwise the water will deplete the oxygen that the roots need so badly. In addition, the water becomes cloudy and is enriched with nutrients after a few days. Watercress always needs clean and fresh water. Apart from this, the plant may need protection against the cold. Although watercress is basically adapted to temperatures in moderate climate zones, in contrast to larger water bodies and streams, a small water body in a tub will freeze. Therefore, use some garden fleece or other type of protecting material to cover the flower pot.
A big advantage of watercress is that it does not need to be fertilised.
How to care for watercress in summary:
- Always keep it moist
- Change water every two days in pot culture
- Use winter protection if growing watercress in a pot
- Do not fertilise watercress
Next, let’s focus on how to harvest watercress. The green leaves and shoots are harvested from September until around May, when the plant begins to flower. The plant can be harvested throughout the winter. All you have to do is cut back individual shoots. However, you should not be too radical and let the plant regain its vigour.
In principle, green parts of the plant should only be harvested from running water. If there is no water circulation or if the water is not replaced regularly, bacteria can attach themselves to the plant. Either way, it is of course important that the harvested plant parts are carefully washed.
Apart from leaves and stems, flowers are also suitable for consumption and the seeds can also be used.
Watercress: pests & diseases
Like almost every plant, watercress can also be plagued by various plant diseases and pests. One of them are snails, which are easy to spot as they feast on the parts of the plant that protrude from water. You can collect them simply by hand.
Aphids (Aphidoidea) can also be found here from time to time. They can be rinsed off well with water.
Wild ducks can be a problem in larger bodies of water. In this case, you can use nets to protect your watercress crop.
Apart from pests, the downy mildew fungus (Peronospora parasitica) can also be found on the watercress from time to time.
Yellow leaves on watercress
If the watercress leaves turn yellow, it is a sign that something is wrong. First of all, it is important to check whether the plant has always had enough water. The water-loving plant cannot cope with a lack of water and droughts.
Another cause could be a root problem. A lack of oxygen or pests in the root area can lead to the roots dying.
Watercress does not flower
Watercress blossoms every year around May. Freshly sown plants may still be too young to flower at this time. These plants will only start to flower next year.
Watercress: benefits & use in the kitchen
Watercress owes its spicy pungency to the mustard oil glycoside gluconasturtiin. Many representatives of the cruciferous plant family contain mustard oil glycosides. This is how cabbage (Brassica), for example, gets its typical cabbage-like smell. The taste of this mustard oil glycoside makes watercress an ideal refinement for soups and salads. It also works well with cheeses and spreads.
The watercress flowers can be arranged perfectly as a decoration. In dried form, the small seeds of the plant, on the other hand, lend fresh flavour to home-baked bread.
Many wonder: is watercress good for you? As watercress can be harvested fresh in winter, it is an important source of vitamins A and C during the cold season. It also contains iron, iodine and folic acid. Watercress is therefore very healthy. And not only that, it is also used in herbal medicine. It is said to stimulate the appetite and metabolism and is even used as an aphrodisiac. Caution is advised in advanced stages of pregnancy, because watercress can cause pain if consumed in excessive quantities.