When to Plant Oca in Melbourne, Cool Temperate Guide
Also called oca, New Zealand yam.
What this month normally looks like in Cool Temperate
In October the Cool Temperate zone normally runs 19°C by day and 8°C overnight, with about 67 mm of rain over 9 or 10 wet days. The coldest October night on record across the zone was -3.0°C, so a late frost is not out of the question. Averages 1991 to 2026, 28 postcodes, SILO.
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This Oca guide is written for the Cool Temperate zone, which takes in Melbourne, Hobart and Geelong. Somewhere else? Your postcode picks the right one.
Not your zone? Cairns Brisbane Sydney Canberra Alice Springs Perth
Also handy: will it frost this week? and what grows in shade.
- Planting window
- Sep to Oct
- Days to harvest
- about 17 weeks
- Sun
- Full sun to part shade
- Water
- Low
- Spacing
- 25 cm apart
- Soil pH
- 5.5–7.0
Oca (also called New Zealand yam, uqa) is a South American tuber crop that produces colourful, waxy-skinned tubers in shades of red, orange, yellow, and white.
Published · By GardenBuddy.au
Planting dates, current conditions and prices on this page update daily.
Planting Calendar for Cool Temperate
- Jan -
- Feb -
- Mar -
- Apr -
- May -
- Jun -
- Jul -
- Aug -
- Sep ✓
- Oct ✓
- Nov -
- Dec -
S = Seed Tray T = Transplant D = Direct Sow
Want a nudge when it is sowing time?
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How to Grow Oca in Cool Temperate Australia
- Soil
- Free-draining soil rich in organic matter. Avoid waterlogging which causes tuber rot. Light, friable soil produces the cleanest tubers. Amend heavy soil with compost and coarse sand.
- Salt
- Moderately sensitive. Copes with a little salt, but the harvest drops on salty bore water.
- pH Range
- 5.5-7.0
- Sunlight
- Full sun to light shade. Tolerates more shade than most root crops.
- Spacing
- 25cm apart, 45cm between rows
- Watering
- Keep well-watered during hot, dry periods. Oca is relatively drought-tolerant but consistent moisture improves yields. Reduce watering as foliage dies back in autumn/winter.
- Good companions
- Garlic, Onion, Marigold
- Keep away from
- No known antagonisms, but keep away from other Oxalis species to prevent confusion with weeds
- 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.
Cool Temperate Growing Tips for Oca
Recommended Varieties
- Red oca
- Yellow oca
- White oca
- Sunset
Key Challenges
- Early autumn frost may kill foliage before tubers reach full size
- Short autumn tuber-formation window
Pro Tips
- Melbourne gardeners can grow good oca with patience
- Plant as early as possible after last frost to maximise the vegetative growth period
- The more leaf area built up before autumn, the more energy available for tuber formation
Pests and problems for Oca in Cool Temperate
- Fungal and Insect Damage Low
- Common Garden Snail Watch
- Slugs Watch
- Aphids Watch
- Root Rot / Tuber Rot Plant only in well-drained soil. Raise beds if necessary. Do not overwater. Ensure tubers are not sitting in saturated soil. Watch
- Oca Virus Complex Source clean planting material from reputable suppliers. Control aphids. If yield declines over several years, obtain fresh virus-free... Watch
Harvesting Oca
When ready: Foliage has completely died back (either from frost or natural senescence). This is typically 15-20 weeks after planting in temperate zones. Do NOT harvest early. Tubers only reach full size in the last 6-8 weeks as the plant channels energy from dying foliage into tuber growth.
How to harvest: Use a garden fork inserted 20-30cm from the plant base. Lift the entire clump gently. Tubers are attached to the plant base by thin stolons. Collect all tubers carefully as they break off easily. Save some of the best tubers for replanting next season.
Storing and preserving oca
How to keep it
- Cool Storage. Store unwashed tubers in a cool (5-10C), dark, well-ventilated place. Paper bags, open trays, or boxes with newspaper between layers. Higher temperatures cause sprouting; refrigerator temperatures cause sweetening. Keeps: 2-4 months.
- Sun-Curing (for sweetness). Expose harvested tubers to sunlight for 3-7 days. This converts some of the oxalic acid and increases sugar content, making tubers sweeter and less tangy. Turn daily for even exposure. Keeps: Storage life is not extended, but eating quality is improved.
- Freezing. Wash and slice or dice. Blanch 2-3 minutes. Ice bath, drain. Freeze on trays then bag. Alternatively, roast first and freeze cooked. Keeps: 10-12 months.
- Dehydrating (Chuno-style). Traditional Andean method: freeze tubers overnight (or use freezer), thaw in sun, squeeze out liquid. Repeat 3-5 times. The result is a dry, lightweight, long-storing product. In Australia, freeze in freezer overnight, thaw in sun, press. Repeat until dry and light. Keeps: 12+ months.
- Pickling. Wash and slice thinly. Pack into sterilised jars. Cover with hot vinegar brine (vinegar, water, sugar, salt). The tangy flavour of oca works well as a pickle. Ready in 1 week. Keeps: 3-6 months refrigerated.
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 Oca
Can you grow oca all year round in Melbourne?
No. In the Cool Temperate zone the planting months are Sep to Oct. Outside that window it either bolts, sulks or gets cut down by the weather.
What else is oca called?
Oca is the usual Australian name. Overseas seed packets and recipes call it oca, New Zealand yam. Same plant, same growing advice.
When should I plant Oca in Melbourne?
Plant tubers in spring once hard frosts ease, as the tops are frost tender. Tubers only swell as days shorten in autumn, so leave plants until frost kills the tops before digging.
How do I know when Oca are ready to harvest?
Foliage has completely died back (either from frost or natural senescence). This is typically 15-20 weeks after planting in temperate zones. Do NOT harvest early. Tubers only reach full size in the last 6-8 weeks as the plant channels energy from dying foliage into tuber growth.
What are the best Oca varieties for Melbourne?
Recommended varieties for the Cool Temperate zone include: Red oca, Yellow oca, White oca, Sunset.
What grows well with Oca?
Good companion plants for Oca include: Garlic, Onion, Marigold.
Are oca salt tolerant?
Only a little. Oca 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 Cool Temperate zone, Melbourne is its reference city.