Grow sweet potato

Sweet potatoes (Ipomoea batatas) are a versatile and nutritious vegetable, full of antioxidants, vitamins and fibre. They feature in many global cuisines and are valued for their edible leaves in addition to their delicious tubers. Believed to have originated in central to southern America, sweet potatoes have long been a cornerstone in edible gardens around the world, mainly due to their portability and long storage qualities. They’re also easy to grow and could be a delightful addition to your home-grown produce, whether you have a spacious garden or a small balcony.

Getting started

You need at least four to five months of warm, sunny, frost-free weather to cultivate sweet potatoes. Plant from September to November in warm temperate and subtropical coastal areas and year-round in the tropics. Choose a spot with free-draining soil, ideally sandy or loamy. Tubers are prone to rot in heavy soils. To improve your chance of success in such earth, add compost to open up the soil and create mounded rows at least 20cm high to improve drainage and provide a greater depth of improved soil for tubers to develop. 

To start your crop, buy a healthy tuber from a greengrocer and plant it in a pot filled with potting mix. In a few weeks, it will start producing shoots. Once these shoots reach about 30cm in length, cut them off, strip the lower leaves, and plant them in your prepared soil, 25–30cm apart. (If you know someone who is growing sweet potatoes, you can skip the first step by asking them for some cuttings.) Keep the freshly planted cuttings well watered for the first two weeks while they produce roots. Some of the roots that form will eventually swell and become tubers.

How to grow sweet potato

Water your sweet potato plants whenever the soil feels dry. They’re not heavy feeders, so an occasional sprinkle of blood and bone or pelletised poultry manure is plenty. The vigorous vines should be trimmed regularly to stop them spreading. Remember, those leaves can be eaten – steamed, stir-fried or added to soups and curries.

The tubers can be harvested about five months after planting. To find them, look for thicker stems at ground level, then gently loosen the surrounding soil with a garden fork to lift the tubers. Harvest a few larger tubers as needed, leaving the rest to mature further. In cold areas, all the tubers should be harvested before the first frost.

For long-term storage, the tubers need to be ‘cured’ in a warm, humid environment: brush off the soil and place in a single layer in a plastic bag with a few holes cut into the bag for ventilation, for one to two weeks. The cured tubers can be stored in a cool, dark, dry place for four to five months. 

Grow sweet potato in containers

If you have limited space, or if your soil is heavy, you can grow sweet potatoes in containers. Fill a pot at least 300mm wide with good potting mix. Plant your cuttings, place the container in a sunny spot and water regularly, especially in hot weather. As they grow, the vines can be trained over a balcony or trellis for easy management – trim when they get too long. When it’s time to harvest (usually four to five months after planting), tip everything out of the pot to reveal the tubers and take some cuttings from the vine to start your next crop. 

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