Freshly harvested watercress
How to grow watercress from seed

Freshly harvested watercress grown in pristine conditions is fantastically healthy for you. It is one of the oldest known leaf vegetables consumed by humans, and is known to be particularly rich in vitamin K, as well as containing significant amounts of vitamin A, vitamin C, riboflavin, vitamin B6, calcium, and manganese. What's more it tastes good too.

Want to grow it yourself? Well you can, but how do you grow watercress from seed?

Although the natural habitat of watercress is amongst slow moving bodies of water, their seed can be germinated in pots much like any other plants seed. In fact they are so easy to grow they can even be started off indoors. The only thing you need to make sure of – apart from keeping them soaked at all times – is that you are using an alkaline compost. This type of compost can easily be made up by mixing 1 part limestone grit to 2 parts John Innes seed compost.

Start by using plastic pots which have had small holes (approximately 3-4 mm in diameter) drilled into the sides. Fill them with the compost mix and push 3 or 4 seeds – evenly spread - into the surface to around about an inch deep. Fill a suitable, high-sided container with water and place the sown pots into it. Leave the water level so that it is about ½ to 1 inch below the soil level. Place the container outside in a bright position, but out of direct sunlight and extremes of temperature. The important thing to remember here is to ensure the soil remains soaked at all times and to change the water for fresh each day to avoid fungal infections. You can expect to see the new seedlings emerging any time from 7-10 days.

Watercress beds in Warnford, Hampshire
How to grow watercress from seed
After a further 2-3 more weeks in the pot, the seedlings should be big enough to be transplanted in to their permanent positions. The best times of year for this would be at the end of spring and beginning of autumn as this will give them plenty of time to establish before they need to cope with the extremes of summer and winter temperatures. However, so long as their final position allows them to be covered by at least a few inches of water throughout the year, they can be planted at almost any time.

Ideally, you would be planting into a shallow river or small stream. Just dig a few holes in the sides of the stream bed, making sure the holes are roughly a foot apart. Make sure that when planted, the leaves of your watercress are comfortably floating on the water's surface.

If the body of water they are being kept in is enclosed - such as a large pond - and fed by a re-circulating pump, then as the watercress plants naturalise they can be propagated by simply breaking off sections of plants - making sure that they have a healthy root system attached – and allowing them to just to float around on the water's surface. There are normally enough nutrients present in the water (especially if you are keeping fish) for the plants to continue growing without the need to take root and receive its nutrients from the soil.

Harvest your watercress leaves as and when you need them. This can be from the end of spring and onward into early summer. You will have to wait for late autumn however if you wish to harvest any more, as the leaves will become bitter and inedible once the plant comes into flower.

Main image credit -
In text image - By Pierre - Own work, CC BY 3.0,

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