The sweet potato,referred to as a yam in North America and Kumera in New Zealand, is part of the morning glory family. Like the yam, it is an ancient vegetable that has a tuber like appearance. It has a sweet flavor and is rich in nutrients. A personal favorite use is sweet potato gnocchi.
Sweet potatoes do best in a tropical or subtropical climate, but they can be grown in many climates. Their growing season is long and they just love warm weather. 20°C is minimum. They can be grown in temperate areas as long as warm temperatures are maintained. Frost is bad news for sweet potatoes.
Ideally, it will be very wet during growth, tapering to a dry period at harvest time.
Varieties of Sweet Potato
There are many many types of sweet potato, but they all fall in to three vague groups. Yellow and white fleshed ones are quite dry, and more red-colored varieties are more moist and soft. The third group contains varieties that are grown for animal consumption only. Most people that have eaten sweet potato from the supermarket or greengrocers will be familiar with the moist, orange variety.
Planting Sweet Potato
Sweet potato is grown from cuttings or tubers. You can grab cuttings from other kind gardeners easily enough. Simply get a cutting of the foliage about a 8 inches (20cm) in length and remove all the leaves except for the tiniest ones at the end. Plant the cutting with the leaves showing just above the surface of the soil.
If you can’t get your own cuttings, you can grow your own from a store-bought sweet potato. Plant the potato in a pot of seed-raising mix or sand. It will grow shoots which can be cut off and planted as above once they are 8 inches (20cm) in length.
Sweet potato likes well prepared soil with excellent drainage and a pH of around 5.5 to 6.5. Dig in organic matter a month before planting.
Planting techniques will vary depending on rainfall. Heavy rainfall (tropical/sub-tropical zones) usually requires the sweet potato cuttings to be planted in ridges to allow for run off of heavy rain fall. The ridges should be a foot (30cm) tall and roughly 4 feet apart. Plant the cuttings 1 and 1/2 feet (45cm) apart just below the soil, exposing around half of the cutting. In temperate climates without heavy rainfall there is no need to plant in ridges, but follow the same spacing techniques.
Growing Sweet Potato
Watering is generally only needed in temperate zones and especially in the early stages of growth. Be wary of high nitrogen fertilizers, which will cause excessive stem growth. They enjoy high potash fertilizers once every month or so. Trim back the vines occasionally to encourage growth.
Growing sweet potato in containers is easy. You will need a container about a foot (30cm) deep and a foot or more wide.
Harvesting Sweet Potato
Sweet potato takes 4 to 6 months to ripen. Warmer weather will cause it to ripen faster. Maturity is indicated by yellow foliage that is dying back. They can be stored for a few months time in a dry place.
Threats to Sweet Potato
They are generally free of problems, aside from rot, which is caused by too much moisture in the soil.