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Sweet potatoes

SWEET POTATOES are popular in many parts of the world, including the US and the Caribbean Islands. They are a favourite ingredient for cake-making in the Algarve and, thanks to experimentation by northern europeans, their popularity is spreading.

Sweet potatoes need hot weather, average quality soil and a reasonable amount of watering. They are easy to grow, but not straight forward.

A complicated business

If you start early enough, which you probably haven’t, you plant whole or halved sweet potatoes in the soil in March. Within a few weeks, these potatoes would have sprouted and, by now, have long trailing stems of heart shapes leaves. These stems are then cut in June and the cuttings (slips) planted, to produce the sweet potatoes. Luckily for us, the Algarve has an army of elderly farmers who regularly produce a surplus of slips and sell them in local markets to the likes of you and I. They are always sold on Sunday mornings in the farmers’ market (second and fourth Sunday of the month) in Monchique and at other markets around the country. If in doubt, ask a vendor selling sweet potatoes where you can get slips.

Growing them

• Dig square beds, with raised walls of earth around the edges (30cms high), around two metres x two metres.

• Flood the centre of the bed until the water reaches the height of the raised edge. Push the slips 10cm deep into the side of the raised edge, leaving around 40cm between slips. Flood again.

• Leave for four days – flood again.

• Continue watering every four days, ensuring the trench fills up completely, allowing the water to slowly penetrate deep into the soil. This will enable the plant to grow deep roots.

• Keep the beds weed free.


The stems you planted will look quite poorly for a few weeks until they grow roots of their own. They will then begin to grow vigorously, developing long trailing stems. Deep under the ground the small tubers will be forming.

The potatoes should be sufficiently swollen by October/November, and need to be dug before the weather turns cold or excessively wet. Dig carefully around the plant, easing out the sweet potatoes, and don’t be surprised at tubers weighing more than a kilo!


Once dug, keep the tubers for two weeks in warm (+30 degrees) humid, conditions. Then store in a place that is safe from frost. They will still be usable by June next year.

Eating them

Portuguese recipe books are full of recipes for all sorts of cakes using sweet potatoes. However, they can also be used in many other ways. They make an excellent soup when mixed with pumpkin and a little curry powder. They make a good thickener for casseroles and can also be used in vegetable curries. If mixed with ordinary potatoes, they can be mashed, with a little butter, producing a mashed potato that tastes far superior to the usual product. For me though, roasted sweet potato is the best. The potatoes are peeled and cut into small cubes, brushed with olive oil and covered in black pepper. A roasting tin, lightly coated in olive oil, is heated in an oven until very hot. The potatoes are then added and, after 20 minutes or so, they begin to caramelise and are ready to eat. They are delicious eaten with a roast dinner.

• If anyone can help with more information on organic supplies please send me details. If you have any gardening nightmares or successes to share, e-mail me at [email protected]. Write Virtual Vegetables in the subject column, so that the message isn’t mistaken for spam and binned!