How to grow sweet potato in Australia
Also known as: Kumara
Sweet potatoes are botanically unrelated to regular potatoes — different family, completely different growing requirements. Sweet potatoes love heat, hate frost, need a long warm season, and grow as sprawling vines rather than upright bushes. They thrive in Darwin, Brisbane, and Townsville; they're a stretch in Melbourne and Hobart. They're also one of the most generous vegetables in the garden — a single planting can produce 3–5kg of tubers, and the leaves are also edible.
When to plant
Sweet potatoes need 4–6 months of warm conditions to produce decent tubers. They're killed by frost and slow to start in cool conditions.
September to February. Sweet potatoes are essentially perennial in tropical climates and produce reliably year-round if not killed by waterlogging in the wet season. Plant during the late dry season for an extended growing period.
September to January. Long warm season suits sweet potatoes well. Plant in spring for harvest in autumn.
October to December. Sydney and Perth grow good sweet potatoes. Adelaide is at the cooler edge — choose faster-maturing varieties.
November to early December. Sweet potatoes are marginal in Melbourne — the season is short, and they need every warm week. Plant against a north-facing wall for reflected heat. Choose shorter-season varieties.
Don't bother in the open garden. Sweet potatoes need more sustained warmth than Hobart or Canberra summers provide. A polytunnel or greenhouse could make it work, but most cool-climate gardeners are better off skipping this crop.
September to October. Sweet potatoes tolerate dry heat well. Plant before peak summer and harvest in autumn.
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Open the full planting calendar →How to plant
Sweet potatoes are grown from "slips" — leafy shoots produced from a mature tuber. Slips are available from garden centres and online nurseries in spring. You can also produce your own by suspending a sweet potato (root end down) half-submerged in a glass of water on a windowsill — within 4–6 weeks it produces slips that can be twisted off and planted.
Spacing: 30–50cm between plants in rows 60–90cm apart. The vines sprawl across 2–3m, so allow space or train them up a trellis.
Depth: Plant slips 5–10cm deep, with most of the stem buried and 2–3 leaves above ground.
Soil: Well-drained, sandy or loamy soil with moderate organic matter. Too much nitrogen produces leafy plants with poor tuber development. Slightly acidic to neutral pH.
Mounding: In areas with heavy clay or poor drainage, plant on mounded rows 20–30cm high. This improves drainage and warms the soil faster.
Pots, raised beds, or in-ground?
Sweet potatoes are vine crops that need space, which makes pot growing challenging but not impossible.
In-ground is the standard for sweet potatoes. The sprawling vines need room, and the unrestricted root run produces the largest tubers.
Raised beds suit sweet potatoes very well. Improved drainage and warmer soil get plants going faster — particularly useful in marginal climates like Melbourne. Train vines along the edge of the bed or over the sides.
Pots can produce sweet potatoes but require large containers — minimum 40 litres per plant. The vines will spread well beyond the pot. Wide rather than deep is better; tubers form near the soil surface. Specialised "potato bags" work well. Yields are smaller than in-ground but a single bag can produce 1–2kg of tubers. The vines are decorative and can trail attractively from a balcony pot.
Sunlight & water
Full sun — 6 to 8 hours daily. Sweet potatoes need warmth and light to produce well.
Water consistently through the establishment phase (first 4–6 weeks) and during active vine growth. Reduce watering for the last 3–4 weeks before harvest — wet soil produces watery tubers with poor storage life.
When and how to harvest
Sweet potatoes are ready when the leaves start to yellow, usually 4–6 months after planting. In tropical climates where plants don't go dormant, harvest as needed — leave the vines growing for continuous production.
Dig carefully with a fork — sweet potato tubers are fragile and damage easily. Start digging well away from the central crown to avoid spearing tubers.
Curing is essential for storage. After harvest, place tubers in a warm (24–30°C), humid spot for 1–2 weeks. This heals minor wounds and toughens the skin. A covered verandah in summer works well.
Storage: Cured sweet potatoes keep 3–6 months in a cool, dry, well-ventilated spot. Don't refrigerate — cold damages them. Storage above 10°C is essential.
The leaves are edible — pick young growing tips and cook like spinach. A mild, slightly sweet flavour. Tropical gardeners often harvest leaves continuously through the growing season without affecting tuber production significantly.
Common problems
Poor tuber development with lots of vine growth is usually too much nitrogen. Reduce fertiliser; sweet potatoes don't need rich soil.
Wireworm and weevil damage to tubers — burrows and holes. Crop rotation helps; some gardeners report success using nematodes as biological control.
Slow start in cool weather — sweet potatoes won't grow actively until soil is consistently above 18°C. The fix is patience and not planting too early.
Frost damage — vines turn black and die after a single frost. In marginal climates, harvest before first frost.
Companion planting
Plant near: Beans (fix nitrogen but don't crowd), corn, herbs, marigold.
Keep away from: Tomatoes (share some pests), squash and pumpkin (compete for space).
Australian varieties
Beauregard — The dominant commercial variety in Australia. Orange flesh, smooth skin, productive. Suits most climates.
Hawaiian Pink — Pink-fleshed variety with sweet flavour. Smaller tubers than Beauregard. Suits subtropical and tropical climates.
Northern Star — White-fleshed variety, faster-maturing (4 months). A reasonable choice for marginal climates like Melbourne.
Murasaki (Japanese) — Purple skin, white flesh. Drier, more starchy texture. Less commonly available but worth seeking out.
Centennial — Heritage orange-fleshed variety. Productive in warm temperate to tropical climates.