How to grow and harvest watercress
Make your own Cream of Watercress Soup from this easy to grow green.
Words: Nadene Hall & Jenny Somervell
When you live rurally, odds are there’s a drain or creek somewhere nearby with a carpet of watercress in it. For health reasons it’s best to pick it for your stock and not your salad; you have no way of knowing if the water it is sitting in is contaminated by stock grazing in or near the water, by farm run-off, or if the site has been sprayed out. There is also the possibility of it being infested with liver fluke, a deadly parasite; the risk is just too great.
Growing watercress in your own garden is simple, although it can be a bit messy, but it’s a great leafy green to enjoy in winter. Watercress is a member of the mustard family, rich in vitamins A and C, niacin, thiamine and iron. It also adds a great peppery taste to winter soups or a fresh salad but fresh shoots can be picked all year round.
Watercress grows best in running water, but can easily be grown in pots. Photo: Dreamstime
9 TIPS FOR GROWING WATERCRESS:
Ideally watercress likes to be in a fresh running stream but that’s a big ask for most home gardens. I’ve heard it grows well under a dripping tap. I can’t see why not, provided there is free drainage as it dislikes stagnant water, and dripping taps abound in my garden, one of the many not-yet-got-around-to-it jobs.
Watercress can also be grown in pots which then should sit in a watertight container. Pop a few stones in the bottom, fill with good quality potting mix mixed with a little lime and grit, and set pots inside the larger container. Fill with water so the bases are sitting in water, but don’t let the level go over the rim.
Space young plants 22-30cm apart in sun with part shade on hot afternoons. Plants need constant fresh water so empty the large container every two to three days and replace with fresh water.
Apply liquid feed as needed to keep growth lush and healthy.
Watercress is surprisingly hardy and tolerates being frozen, although your buckets might not!
Watercress virtually propagates itself! The quickest way is to place stalks from a supermarket-bought plant in a jar of water, changing the water every few days. Fine roots will quickly appear and the rooted plantlets can be transplanted into containers as above.
Seeds germinate in 8-10 days. They are best sown in spring or autumn as plants tend to run to seed in mid-summer.
Watercress does best in a rich, fertile soil.
A large leaf, higher-yielding variety called Nasturtium officinale Aqua Large Leaf is available from King Seeds, and there is also a sterile, bronze-leaved variety Nasturtium microphyllum.
HOW TO HARVEST
– Use scissors to snip the tops stems when they are about 15cm long but never take more than a third of the plant at any one time.
– Do not pull on stems as the whole plant may come out of its container.
– Watercress wilts quickly and is best harvested for immediate use. It will hold in the fridge up to 3 days in a plastic bag but prefers being submerged in water. It will not dry or freeze.
HOW TO GET FREE SEEDLINGS:
You can buy watercress from your supermarket and grow it on: choose a couple of plants that have bits of root left on them and place them in a glass of water. Refresh the water each day and you should be quite quickly rewarded with root growth. Once you have a good rootball, you can plant them out .
CREAM OF WATERCRESS SOUP:
The trick with getting a great-tasting soup is not to let the fresh leaves sit for too long on the heat or they will go very bitter.
170g watercress, washed and dried
1 tbsp sunflower or canola oil
1 tbsp butter
1 onion, minced
1 potato, peeled and diced
1¾ cups vegetable stock
1¾ cups whole milk or light cream
salt and freshly ground pepper
Heat the butter and oil over low heat until butter is melted. Add the onion and cook for about 3 minutes until soft but not brown. Add the diced potato and cook for another 3 minutes. Cover and allow to cook for 5 minutes, stirring once or twice. Trim watercress leaves from the stems. Roughly chop the stems. Add the stock and milk to the onion/potatoes and stir in the chopped stems. Season and bring to the boil, then reduce the heat, cover and allow to simmer for about 12 minutes or until the potatoes are tender. Add all but a few of the watercress leaves (reserve some for garnishing) and simmer for another 2 minutes.
Working in batches, purée the soup in a food processor or blender. Return the soup to the saucepan and gently heat with the reserved whole leaves. Taste and season with the lemon juice and more salt and pepper if necessary. Add a dollop of sour cream or creme fraiche.