Water spinach (Ipomoea aquatica) is also called Kang kong, Ong Choi (Ung Choy).
In South East Asian, it is a commonly consumed leaf vegetable, usually fried with garlic or shrimp paste (belachan). The pointed leaves wilt down to nothing the same way as spinach does and the hollow stems are served with a slight crunch. I find the texture really appetizing and much tastier than regular spinach.
So, can they be grown in the UK?
Water spinach can be easily sown from seed. The challenge is actually finding the seeds and your best bet is to search online. Nicky's Nursery stocks seeds for £2.15.
Another option is to buy and propagate your own plants from freshly store bought ones. Just cut off the tops and place the stems in water for a few days and roots will start to emerge.
This photo shows my kangkong at three different stages. I usually sow seeds in small containers such as an old supermarket fruit box, which is ideal placed over a tray to keep soil moist at all times. Once seedlings emerge, transplant into larger pots.
The pot below will not be sufficient in terms of size and so these young plants will be transplanted once more into their final positions in larger pots.
How to grow water spinach:
Water spinach is a semi-aquatic and tropical plant so it grows well in the heat and in wet conditions. They will thrive in full sun and in temperatures over 24 °C - I grow mine in the greenhouse in the summer.
Place a large pot filled with soil over a saucer.
Sow seeds directly into pot or plant young plants into pots.
Water daily and check that the soil is always kept damp.
Harvest
Water spinach can be harvested using a cut-and-come-again method. You simply cut the main stems leaving an inch of stem to continue grow in the pots. After a few weeks, it will sprout new leaves and stems.
Please note growing restrictions in some countries like the US due to it being classified as a noxious weed and invasive species!