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Sweet potatoes


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Teacher, Paul Mckay, left London to live a self-sufficient existence in the Monchique hills with his partner Martyn. He keeps an assortment of animals and grows a variety of crops in an eco-friendly way – all on a limited income.

SWEET POTATOES grow easily and reliably in the hot months in southern Europe. The warm season in northern Europe is too short for the plants to produce a worthwhile crop.

In Portugal they produce a very heavy crop of firm sweet potatoes, ready for harvesting in late autumn.

Sweet potatoes can be planted as soon as the weather has warmed up, right the way through May and June.

The plants are planted from slips (cuttings from a parent plant). If you want to produce your own slips you need to start earlier in the year by planting whole potatoes in late February. These plants quickly produce numerous growing points and these can be cut off into 15 – 20cm slips (each with two or three leaves) to be planted directly into the soil. Slips are sold this time of year, quite cheaply, in most of the Algarve markets.

Growing sweet potatoes

Keep the slips in a cool place or in a bucket of water for as short a time as possible. In the late evening, when the temperature falls, each slip should be planted into the soil. Ideally, arrange the soil so that slightly raised beds surround a sunken square that can be deeply flooded. The slips are planted firmly into the raised bed, each about 30cm apart from its neighbour.

When the square is flooded, the water will be absorbed into the raised bed, ensuring the roots get sufficient moisture but not too much; too much water could lead to rotting. During the first 10 days or so, the plants will droop and may appear to be dying – don’t panic. If the bed is flooded every three to four days, the roots will establish themselves and the plants will perk up.

This method of cultivation appears to encourage the plants to grow strong roots under the part of the bed that receive water. In time, these roots will form the large tubers that are harvested later in the year.

After this initial settling in time, the potatoes will need to be watered every four days. The patch will need to be kept weed free. Apart from this there is very little work to be undertaken. The plants should grow a strong network of long trailing stems covered in heart shaped deep green leaves.


The potatoes should be ready to be harvested towards the end of September/early October, as the night time temperature begins to fall and before the autumn rain arrives. To harvest them, dig very carefully in straight lines in front of the potato patch, turning over the soil quite deeply. Once I find the first potato, I tend to dig carefully around it using a hand trowel, so as not to damage other potatoes near it.


Once collected, the potatoes benefit from being stored at a temperature above 15 degrees Celsius for 15 days. After this, they can be kept in boxes above zero in a dry environment. They will keep for almost a year, although may start new shoots in spring. If you wish to start your own slips next year, remember to keep some potatoes aside for planting out in February.


Sweet potatoes can be eaten in a similar way to ordinary potatoes but have the advantage of storing better, growing with less disease risk and having a lower GI value. They can be roasted, mashed (mixed with ordinary potatoes) or added to soups, curries and casseroles. They are tasty if fried or oven roasted and served with a spicy sauce. Portuguese cookery books are full of hundreds of recipes for using them inside a wide variety of cakes.