The Simplicity of Watercress

Here's a lovely easy recipe for watercress soup given to my mother by a friend.
Put one bunch of well-washed watercress, one pint of stock, one clove of garlic, a pinch of nutmeg and half an ounce of flour into the liquidiser for thirty seconds. Bring to the boil in a pan and cook two to three minutes to thicken the soup. Season to taste. Decorate with a swirl of cream and serve.
Recipes don't come much simpler than that - and it makes delicious soup!

Watercress Soup
Watercress Soup

Watercress is Nasturtium officinale, a shade-tolerant perennial vegetable, and it is almost as simple to grow as it is to cook. I remember once making the claim on Twitter, "Buy some watercress, sprout it in a jar, plant it in your garden and never buy again!" (Basically true but perhaps a little glib! - I have encountered a couple of problems since then which I'll write about below.) If you can't find a traditional three and a half ounce bunch of watercress in your local greengrocers the shorter branches that come in supermarket bags will do fine.

Sprouting watercress from a supermarket bag
Sprouting watercress from a bag

Watercress forming roots
Forming roots

In its natural environment watercress grows in shallow, gentle streams. It gathers most of its nutrients from the flowing water through roots embedded in the gravelly stream bed but also puts out aerial roots on its stems to gather more food. It especially likes slightly alkaline water and grows in abundance in Water Forlorns, the lovely chalk stream which runs through the East Yorkshire town where we live.

Watercress growing in Water Forlorns chalk stream
Watercress? growing in Water Forlorns

It grows there along with Apium nodifolium, fool's watercress, to which it looks rather similar but I am learning that Nasturtium officinale has smooth leaf margins, rounder leaves when young and the leaflets aren't consistently in opposite pairs. (In flower they are easy to distinguish as Nasturtium officinale is a crucifer with four-petalled flowers whilst Apium nodifolium is a umbellifer with five-petalled flowers.) I think the photo shows Nasturtium officinale (with some Apium nodifolium in the bottom left corner) but I wouldn't completely swear to it yet! Fool's watercress is a traditional accompaniment to meat in West Country pies and pasties so it wouldn't be too disastrous to eat it by mistake but the risk of liver-fluke infection from eating wild watercress encourages me to cultivate our own.

When I initially grew watercress (planted in a pot immersed in a tub of water) I found it grew enthusiastically for a couple of months but then became a bit lethargic. Clearly I was failing to replicate its favoured conditions. In his book on perennial vegetables Martin Crawford explains that the plant doesn't like stagnant water and that you need to change the water everyday or two. Doing this helped but, apart from being a chore, it became very awkward when I started using a larger tub in order to fit in more pots of watercress. The tub was too heavy to lift and, without a drain immediately to hand, sluicing away that amount of water on the soil in a small backyard is apt to make things just too muddy.

Thinking I was being clever I formed a plan to resite the watercress pots to a cascade of tubs next to our small water butt. I wanted to arrange for the overflowing water from the butt to run through the tubs and finally discharge into the drain below. But on further thought I realised that watercress wants mineral-rich alkaline water, not rainwater which I believe is slightly acid and has very low levels of minerals.

So my next step will be to simply grow the watercress in a large, fairly deep tray of fertile soil. I'll puncture some fine holes in the bottom so that it drains but not too freely, and water and feed it regularly.

The other problem I've found is that watercress, being in the brassica family, easily falls prey to flea beetle, greenfly and cabbage white caterpillars. I think a fine net may be called for!

Watercress has been grown commercially in the south of England since 1808. Wiltshire grower John Hurd went organic in 1992. He provides a downloadable booklet on his website which gives some nutritional and historical information about watercress along with lots of recipe ideas (most of them simple!)

N.B. I sell a range of perennial vegetable plants on my website.