Potato Farming in farm gardens
The Gnarled sweet potato in the veggie section of the supermarket gives no hint of the plant that produced it. Sweet potatoes come from a dainty ground cover that has green, heart-shaped leaves and small white or pink flowers. It forms a lush vine that sprawls over the ground.
Farming
Where it puts down roots, tubers we know as sweet potatoes grow beneath the soil surface. Even more surprising is to discover that sweet potato is an edible species of the familiar blue-flowered weed known as morning glory.Both vines are in the genus Ipomoea and part of the convolvulus family.
Sweet potato is sometimes called yam and usually thought of as a tropical vegetable from the Pacific islands, however sweet potatoes are native to Central and South America (much like potatoes).These edible tubers spread from America across the Pacific as far as New Zealand perhaps more than 1000 years ago. We often use the Maori name kumara for sweet potato.
Types Of Potatoes
Not so long ago, the only sweet potato most people knew was the greyish white vegie served up along with the Sunday roast beside potato, pumpkin and carrot.Today, most sweet potatoes sold in greengrocers, supermarkets and farmers' markets, and grown in gardens, have orange flesh.
The traditional white or grey-fleshed sweet potato is now the variety that's hard to find but is available from online suppliers as 'Northern Star'.The orange-fleshed form is sold as 'Beauregard' or may not have a cultivar name. Growers of unusual vegetables may like to seek out the purple sweet potato, a variety commonly found throughout Asia.
While it's still served as a roast vegetable. it has become an important ingredient for soups, curries and warm salads.Sweet potato also makes a delicious mash or a crunchy chip.Indeed packets of sweet potato crisps are now sold in the chip aisle in most supermarkets.
The versatile sweet potato is also made into desserts, brewed up as a coffee alternative or added to juices and smoothies (try it with beetroot).There are even sweet potato cocktails on the menu at some bars. These cocktails combine sweet potato syrup (a syrup made from the liquid that comes out of roasted sweet potatoes) with rum, tequila or bourbon.
Sweet potato has also picked up a reputation as being a healthy food choice as it is low-GI yet packed with vitamins and nutrients, including vitamin A and beta-carotene. It's a top source of dietary fibre for those on a low carbohydrate diets.
Growing Plants
Autumn is harvest time for sweet potatoes in most parts of Australia but is also a good time to take cuttings to start new plants in tropical zones. To check to see whether the tubers are ready, gently burrow under the vine. Alternatively, leave the tubers in the ground until the vine dies back when the cold weather arrives.
For an autumn harvest, tubers are planted in spring to grow for at least five to six months. Sweet potato grows best in tropical, subtropical and temperate zones as these areas have the long, warm period these plants need for good tuber formation.In cold and inland regions, cold weather or frost may kill the vine before the tubers have reached an edible size.
Growing sweet potatoes by planting sprouted tubers or grow new vines from the sprouts themselves. In warm climates, take tip cuttings as the plants grow and use these to start new plants.Tubers may sprout unaided, but they can be helped along if placed in a box filled with damp sand (cover the tubers with about 5cm of sand) and allowed to stand in a warm spot.
Start the sprouts in late winter for planting in mid-spring when the sprouts have reached about 30cm long.Cut the sprouted tuber into sections ready for planting.One vine can cover over 3m of ground if given free range, but in a vegetable garden with limited space, space the sprouts or cuttings about 40-50cm apart in rows 90-100cm apart.
They can also be allowed to tumble over the edge of raised beds and allowed to grow over the ground.Set the sprouts about 5-7cm deep to make sure several nodes are covered with soil to allow the all-important root system to form. To grow large tubers, discourage the vine from forming roots as it spreads out.In cold areas or where space is at a premium, sweet potatoes can also be grown successfully in a large container.
Gardening Tips & Tricks
- A 40cm-diameter pot can support one plant.
- Train the vine to grow vertically rather than allowing it to trail along the ground by inserting a climbing frame or a tripod of three tall stakes into the pot.
- Whether they are in the ground or in a pot, keep the plants growing well with regular watering if conditions are dry.
- Keep plants free of competing weeds until they smother the ground when their foliage acts as living mulch.
- Use excess leafy growth from sweet potato vines to feed to the chooks through summer and autumn.
- Keep well watered.
- Provided fertiliser was applied to the soil at planting, no extra feeding should be needed.
- However an occasional liquid feeding will help pot-grown plants.
Harvesting, Storage
As autumn arrives and temperatures drop, vines may begin to yellow and die back. A single frost is enough to kill off even a well-established vine. Gently pull or dig up the vine, taking care not to damage or break the tubers as they bruise or break easily, and damaged tubers don't store well. If the tubers are growing in a pot, simply tip out the contents to harvest the tubers.
Allow the tubers to dry for a few days, wipe them free of soil and store them in a cool, dark place for up to a month. Tubers can also be stored in the crisper section of the fridge but, with so many serving options, they won't be there for long.
Scientific
- Common name: Sweet potato
- Botanical name: 1pomoea batatas
- Family: Convolvulaceae (morning glory family)
- Aspect & soil: Full sun; deep, well-drained soil
- Best climate: All Suitable for: Vegie beds, groundcover
- Habbit: Perennial groundcover
- Propagation: Tubers, cuttings
- Difficulty: Easy