How to Grow Sweet Potato in Australia
Varieties, slips, planting calendars, and curing for storage
Sweet potato is one of the easiest crops to grow in warm Australian climates. Each plant produces 2 to 5 kg of tubers with very little effort. The sprawling vines also make excellent ground cover, smothering weeds and protecting bare soil.
This guide covers how to grow slips, the best varieties, planting times for your region, and how to cure tubers for long-term storage.
When to Plant in Your Region
Varieties
Beauregard
The standard Australian sweet potato. Orange flesh, reliable yields, stores well. Most commercially grown sweet potato in Australia is this variety.
Purple Delight
Vivid purple skin and flesh. Slightly drier texture than orange types. High in anthocyanins. Striking in salads and roasted dishes.
Northern Star
White-fleshed variety suited to tropical and subtropical conditions. Drier, starchier texture closer to regular potato. Good all-rounder.
Hawaiian
Red-purple skin with creamy white flesh. Performs well in subtropical and tropical regions. Sweet flavour when roasted.
Growing Slips
Sweet potatoes are grown from slips, not seeds. A slip is a young shoot that sprouts from an existing tuber. You can buy slips from nurseries, or grow your own at home.
To grow slips, suspend a sweet potato tuber in a jar of water using toothpicks, or bury the bottom half in a pot of moist potting mix. Place in a warm, bright spot. Shoots will appear in 2 to 4 weeks.
Once shoots reach 15 to 20 cm long, snap them off the tuber. Place the snapped slips in a glass of water and roots will develop within a week. They're ready to plant once roots are 3 to 5 cm long.
Planting
Sweet potato slips need warm soil to establish. Wait until soil temperatures are consistently above 20 degrees Celsius before planting out. Cold soil causes slips to sit and rot.
Plant slips 30 cm apart in mounded rows. Mounding the soil improves drainage and gives the tubers room to expand. Push each slip into the mound so that the bottom few leaves are buried.
Sweet potatoes need full sun and prefer sandy or loose soil. Heavy clay soils restrict tuber growth and produce misshapen, forked tubers. If you have clay soil, build raised mounds with added compost and coarse sand.
Growing
Sweet potatoes need minimal care once established. The vines spread 2 to 3 metres in all directions, covering the ground and suppressing weeds.
Don't fertilise with nitrogen. Too much nitrogen pushes the plant to grow lots of leafy vine at the expense of tubers. If your soil is reasonably fertile, no fertiliser is needed at all.
Water consistently but don't overwater. Sweet potatoes tolerate dry spells better than most vegetables, but consistent moisture produces the best-sized tubers. Reduce watering in the last few weeks before harvest to toughen the skins.
Harvesting
Sweet potatoes are ready 4 to 5 months after planting. The leaves will start to yellow as the tubers mature. In cooler areas, harvest before the first frost because frost kills the vines and can damage the tubers.
Dig carefully with a garden fork, not a spade. Tubers can extend 30 cm or more from the base of the plant, so start digging well away from the stem. Damaged tubers won't store well.
After digging, leave the tubers in the sun for a few hours to dry the soil off the skin. Brush off loose dirt but don't wash them.
Curing and Storage
Curing is the step that transforms starchy, freshly dug sweet potatoes into the sweet, creamy tubers you buy at the shops. The process converts starches into sugars and heals any skin damage from harvesting.
Cure sweet potatoes in warm, humid conditions at 25 to 30 degrees Celsius for 7 to 10 days. A covered porch, greenhouse, or warm shed works well. Place them in a single layer with good airflow. Don't stack them.
After curing, store sweet potatoes in a cool, dry spot (around 13 to 15 degrees). Properly cured tubers keep for 4 to 6 months. Don't refrigerate them. Cold temperatures damage the flesh and create a hard, unpleasant texture.
Common Problems
Sweet potato weevil
The main pest in tropical and subtropical areas. Weevils bore into tubers and stems, making them inedible. Rotate your planting site each year and always use clean, pest-free planting material. Mounding soil over exposed tubers helps prevent weevil access.
Vine sprawl
Vines can spread well beyond the garden bed and root at the nodes, producing small scattered tubers. Redirect vines back into the bed regularly. Some growers trim excess vine growth to keep plants contained and focus energy on the main tubers.
Cracking
Tubers crack when watering is inconsistent. A long dry spell followed by heavy rain or watering causes rapid expansion that splits the skin. Keep soil evenly moist throughout the growing season to prevent this.
Track Your Sweet Potato Growing
Add sweet potato to your garden in the Planting Season app and get reminders for planting slips and harvest time.
Open the App →Frequently Asked Questions
Can I grow sweet potato from a supermarket sweet potato?
Yes. Place a supermarket sweet potato in a jar of water or half-bury it in potting mix. It will sprout slips in 2 to 4 weeks. Snap off the slips when they are 15 to 20 cm long, root them in water, and plant out. Results vary because supermarket varieties are not always labelled, but it works well for a first try.
How long do sweet potatoes take to grow?
Sweet potatoes take 4 to 5 months from planting slips to harvest. They need warm soil and consistent warmth throughout the growing season. In cooler areas, this limits planting to the warmest months.
When to plant sweet potato in Australia?
Plant slips in spring and early summer once soil temperatures are above 20 degrees Celsius. In tropical regions, plant from September to December. In subtropical areas, October to December works best. Southern regions have a shorter window from November to December.
Can I grow sweet potato in Melbourne?
It is possible but challenging. Melbourne summers are often too short and cool for a full harvest. Choose a warm, sheltered spot and plant early varieties in November. Black plastic mulch helps warm the soil. Expect smaller tubers than in warmer climates.
See also: Sweet Potato in the Plant Library
