When to Plant Sweet Potato in Cairns, Tropical Guide
Also called kumara.
What this month normally looks like in Tropical
In October the Tropical zone normally runs 34°C by day and 23°C overnight, with about 53 mm of rain over 5 or 6 wet days. Averages 1991 to 2026, 37 postcodes, SILO.
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This Sweet Potato guide is written for the Tropical zone, which takes in Cairns, Townsville and Darwin. Somewhere else? Your postcode picks the right one.
Not your zone? Brisbane Sydney Melbourne Canberra Alice Springs Perth
Also handy: will it frost this week? and what grows in shade.
- Planting window
- All year
- Days to harvest
- about 17 weeks
- Sun
- Full sun
- Water
- Low
- Spacing
- 35 cm apart
- Soil pH
- 5.5–6.5
- Shop price
- $4.90/kg
Sweet potatoes are a warm-season, frost-tender crop grown from vine cuttings (slips), not seed. They are highly productive in warm Australian climates, with a single plant producing 2-5 kg of tubers.
Published · By GardenBuddy.au
Planting dates, current conditions and prices on this page update daily.
Photo: Wikimedia Commons
Best Planting Window for Tropical
- Jan P
- Feb P
- Mar P
- Apr P
- May P
- Jun P
- Jul P
- Aug P
- Sep P
- Oct P
- Nov P
- Dec P
P = Planting window
Sweet potato grows year round in the tropics. The best time to plant slips or cuttings is from the build-up into the early wet (Sep-Jan), so they establish before the monsoon rain.
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How to Grow Sweet Potato in Tropical Australia
- Soil
- Well-drained, loose, sandy loam. Avoid heavy clay or waterlogged soil. Do not over-fertilise. Rich soil produces excessive vine growth at the expense of tubers. Slightly raised mounds or ridges improve drainage and warming.
- Salt
- Moderately sensitive. Copes with a little salt, but the harvest drops on salty bore water.
- pH Range
- 5.5-6.5
- Sunlight
- Full sun (minimum 6-8 hours). Heat-loving crop. The more warmth the better.
- Spacing
- 35cm apart, 100cm between rows
- Watering
- Water regularly during establishment (first 3-4 weeks). Once vines are growing strongly, reduce watering. Sweet potatoes are surprisingly drought-tolerant once established. Excessive watering encourages vine growth over tuber development.
- Good companions
- Banana (ground cover), Sweet Corn, Sunflower, Ginger, Peanut
- Keep away from
- No significant antagonisms, but vines will smother nearby low-growing crops
- Grow before it
- Fruiting crops (Tomato, Capsicum, Zucchini)
- Grow after it
- Legumes (Beans - Dwarf, Peas, Broad Beans)
Give the bed 3 turns before root crops go back in. Roots fork and go leafy in fresh manure, so they take the bed after the heavy feeders have used it.
Tropical Growing Tips for Sweet Potato
Recommended Varieties
- Beauregard (orange)
- Northern Star (purple/white)
- Kestle (white)
- WSPF (white skin/purple flesh)
Key Challenges
- Sweet potato weevil is the critical pest
- Waterlogging in wet season
- Storage in humid conditions
Pro Tips
- This is sweet potato's home climate. Yields will be exceptional
- Weevil management is THE priority: sanitation, sanitation, sanitation
- Plant on raised mounds for drainage during wet season
Pests and problems for Sweet Potato in Tropical
- Fungal Blight Moderate
- Fusarium Wilt Watch
- Whitefly Watch
- Common Garden Snail Watch
- Curl grub (scarab beetle larvae) Watch
- Slugs Watch
- Scurf Use clean planting material. Cure tubers at 28-30C with 85% humidity for 7-10 days after harvest (this is critical for sweet potato... Watch
- Black Rot Handle tubers very carefully. Skin is thin and easily damaged. Cure properly after harvest. Use only clean planting material. Sanitise... Watch
- Sweet potato weevil Sweet potato weevil is the critical pest Watch
Harvesting Sweet Potato
When ready: Foliage begins to yellow (4-5 months after planting). Leaves may show autumn colour change. Scratch soil near a plant to check tuber size. In frost-prone areas, harvest before first frost as frost kills vines and can damage tubers.
How to harvest: Cut back vines first. Use a garden fork inserted 30-40cm from the plant base to loosen soil. Lift very carefully. Sweet potato skin is thin and damages easily, and wounds lead to storage rot. Sort into damaged (use immediately) and undamaged (for curing and storage). Do NOT wash before curing.
Storing and preserving sweet potato
How to keep it
- Curing and Storage. CURE first: place unwashed tubers in a warm (28-30C), humid (85%) space for 7-10 days. A covered box with damp towels in a warm room works. After curing, store at 13-15C in a dark, well-ventilated area. Do NOT refrigerate. Handle gently. Any skin damage shortens storage life. Keeps: 4-6 months if properly cured; 1-2 months uncured.
- Freezing. Cook first (bake, boil, or steam until soft). Peel and mash or cut into chunks. Pack into freezer containers or bags. Do NOT freeze raw. The texture becomes unpleasant. Keeps: 10-12 months.
- Dehydrating. Cook until just tender. Peel and slice into 5mm slices. Dehydrate at 55-60C for 8-12 hours until brittle. Store in airtight jars. Can be ground into sweet potato flour. Keeps: 12 months.
- Canning (Pressure Canning Only). Sweet potato is a LOW-ACID food. Pressure canning ONLY - water bath is NOT safe. Peel, cube, pack into jars. Process at 10 PSI for 65 minutes (pints) or 90 minutes (quarts). Do not mash. Cubes only for safe heat penetration. Keeps: 12-18 months.
Canning safety. Low-acid vegetables like sweet potato must be pressure canned, never water-bath canned.
Grow vs buy
A 2.4 m × 1.2 m bed fits 6 plants, about $44 worth at today’s Aldi and Woolworths prices, checked today.
That is roughly 9 kg at $4.90 a kilo.
Draw your sweet potato bed → No account needed.
What sweet potato costs in the shops right now, retailer by retailer, updated daily.
What members get
- Soil and weather from your nearest station
- An email when it's time to sow
- Your own garden plan, including planning from a photo
- Price history and price alerts
- Pest risk alerts for your area
- Full salt and canning detail
Common Questions About Sweet Potato
When do you plant sweet potato in Australia?
It depends on your climate zone, not the calendar month alone. Planting months by zone:
- Tropical (Cairns): all year
- Subtropical (Brisbane): Jan, Sep to Dec
- Warm Temperate (Sydney): Oct to Dec
- Cool Temperate (Melbourne): Nov to Dec
- Cold / Highland (Canberra): Nov to Dec
- Arid / Semi-Arid (Alice Springs): Oct to Dec
- Mediterranean (Perth): Oct to Dec
Can you grow sweet potato all year round in Cairns?
Yes, every month is on the calendar for the Tropical zone, though not every month is equally easy. Sweet potato grows year round in the tropics. The best time to plant slips or cuttings is from the build-up into the early wet (Sep-Jan), so they establish before the monsoon rain.
What else is sweet potato called?
Sweet potato is the usual Australian name. Overseas seed packets and recipes call it kumara. Same plant, same growing advice.
When should I plant Sweet Potato in Cairns?
Sweet potato grows year round in the tropics. The best time to plant slips or cuttings is from the build-up into the early wet (Sep-Jan), so they establish before the monsoon rain.
How do I know when Sweet Potato are ready to harvest?
Foliage begins to yellow (4-5 months after planting). Leaves may show autumn colour change. Scratch soil near a plant to check tuber size. In frost-prone areas, harvest before first frost as frost kills vines and can damage tubers.
What are the best Sweet Potato varieties for Cairns?
Recommended varieties for the Tropical zone include: Beauregard (orange), Northern Star (purple/white), Kestle (white), WSPF (white skin/purple flesh).
What grows well with Sweet Potato?
Good companion plants for Sweet Potato include: Banana, Sweet Corn, Sunflower, Ginger, Peanut.
Are sweet potato salt tolerant?
Only a little. Sweet potato are moderately sensitive to salt, so the harvest drops on salty bore water. Mix salty water with rainwater, and mulch the bed.
Which zone am I in?
Type your postcode into the box near the top of the page and it tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Tropical zone, Cairns is its reference city.