The sweet potato is nutritious and easy to grow, writes Stephanie Choo
WE often cook and eat the roots, stems and leaves of sweet potato. To have your own supply, just propagate from extra tubers or shoot scraps. They sprout easily.
The botanically-named Ipomoea batatas, the sweet potato or Kumara, is one of the oldest vegetables in cultivation. Nicknamed poor man’s food, it is cultivated widely in the tropical and warmer temperate regions and sold at very affordable prices.
Sweet potato sprawls and covers a big area very quickly. It bears purplish, morning glory-type sympetalous blossoms. The herbaceous perennial vine belongs to the bindweed or morning glory family, Convolvulaceae, and is indigenous to Central America.
Since it domesticated there no less than 5,000 years ago, the species has given rise to hundreds of cultivars. They vary in leaf shape, vine length and root, skin and flesh colour, as well as also texture. There are even bush varieties.
This warm-climate crop thrives well, grows fast and yields a plentiful harvest in full sun. All parts of the sweet potato are edible. They are high in minerals, anti-oxidants and dietary fibre and are a good source of vitamin E, protein and calcium.
GROW FOR TUBERS
The flavour and nutritional qualities of the large tuberous root differ with the root colour. Depending on the variety, the flesh can be white, orange or purple. They are oblong-shaped, have tapered-ends and a smooth outer skin.
Store-bought ones may have been treated with anti-sprout chemicals. So to cultivate sweet potato for its tubers, get untreated tubers from any organic shop or farmer’s market.
Sweet potato tuber grows under deep earth. Tuck about 3cm of the pointed end of the tuber into compost rich, loamy, well-draining soil. Each tuber should be 30cm apart and 90cm between rows of raised beds of 15 to 20cm high. Provide close attention and protection for the first week. Feed with mature compost or any organic fertiliser that is low in nitrogen. Eliminate weed and water regularly.
In about 12 to 16 weeks or when the top yellows, harvest the young tubers. Lift the plant carefully with a garden fork or shovel by digging 15cm deep and about 45cm away from the centre of the plant.
Damaged tubers are to be consumed first. Protect tubers from the sun after harvest and do not wash them. Cure tubers by drying them in a cool dry place till the skin can’t be rubbed off with your fingers.
GROW FOR GREENS
The alternate lobed leaves are either palmate or heart-shaped and are more nutritious than the tubers. Cut off about 10cm long of the root ends of the sweet potato greens purchased from the market. If you don’t have time to plant them immediately, sit them in some water at a bright place for it to start rooting first.
Bury 4cm of the bottom roots with some soil in the pot that is at least 30cm deep or plant them directly on a cloudy day. Provide protection from strong sunlight during the first five days.
Weed, water and fertilise with any all-purpose organic fertilisers regularly. In about four weeks, you will be able to pick young tender shoots for cooking and continue to do so anytime as long as the vines are flourishing well. The vibrant foliage of these greens, especially the heart-shaped ones, can double as ornamentals in the garden.
Suspend a tuber over a bottle of water with a few wooden toothpicks poked around it with the tapered bottom part submerged in water. Leave it at a well-lit place. In about a week, the tuber will grow roots and new shoots from the upper end. Transplant the sprouted tuber to a raised bed or re-root the slip sprouts for planting. The process will fascinate children and is great for teaching about parts of plants.