🌍 Built for UK, USA, Canada & Worldwide Gardens Free Growing Guides for Every Region Love It or Your Money Back Secure Checkout Instant PDF Download Checked Against RHS, USDA & Agri-Food Canada Data Free Garden Layout Planner
🌍 Built for UK, USA, Canada & Worldwide Gardens Free Growing Guides for Every Region Love It or Your Money Back Secure Checkout Instant PDF Download Checked Against RHS, USDA & Agri-Food Canada Data Free Garden Layout Planner
Move through the SoilCommander growing library like a course: keep the navigation in place, open the next lesson, and build your garden plan step by step.
Named by Cultivariable: lower stems blacken and soften.
Oca virus diseases (Papaya mosaic virus and unidentified potyviruses)
low
Named by Cultivariable in some varieties, typically mild in impact; RHS's UK conservatory-context page reports the crop as generally disease-free, a genuine difference in growing context kept honest rather than merged.
Oca decline (symptom complex: knobbly tubers, early sprouting, reduced yields, fasciation)
low
A named symptom complex from Cultivariable: knobbly tubers, early sprouting, reduced yields, and fasciation.
Bacterial soft rot (oca tubers, causal agent not yet confirmed)
moderate
Named by Cultivariable affecting tubers; no specific bacterium identified.
Tuberous, short-day perennial grown as an annual crop. RHS rates it H2 (1-5C, tolerant of low temperatures but not surviving freezing). Cultivariable notes it survives to USDA zone 9a (20-25F minimum) but most of that zone runs too hot in summer for good tuber yields.
Cultivariable: plant whole tubers 2-3in deep, 18in spacing between plants, 24-48in between rows for good air circulation; plant after the final frost, through August in cool climates. RHS: separate and replant tubers in autumn or spring.
Vegetative growth
3
Cultivariable: performs best in full sun where summer highs stay below 85F with cool nights; give partial shade in hotter spells. Loose, light soil with added compost or organic fertiliser supports easy tuber harvest later.
Short-day tuber initiation
4
Cultivariable: tuber formation only begins once day length drops to 12 hours or less, starting after the autumn equinox (22-23 September) -- around six weeks of short days is needed before a reasonable harvest is possible.
Harvest
8
Cultivariable: harvest no earlier than early November, with the third week of November giving roughly 80% of potential yield; loose soil makes lifting the tubers easier and reduces damage.
When to pick: Cultivariable: harvest no earlier than early November -- tuber formation only begins after the autumn equinox once days shorten to 12 hours or less, so a third-week-of-November harvest captures roughly 80% of potential yield.
Storage
40F/4C at 90%+ humidity gives storage life over a year (Cultivariable); flavour mellows and loses acidity over 4-6 weeks if stored at room temperature instead.
A well-established planting of oca (Oxalis tuberosa) -- flowering doesn't need to be encouraged or removed for a good tuber crop, unlike some root vegetables.
Oca's leaves are unmistakably clover-like, in three heart-shaped leaflets -- a useful identification feature, since oca is a distant relative of common wood sorrel and shares its leaf shape.
Cultivariable notes oca performs best where summer stays below 85F with cool nights -- conditions that also keep the foliage looking fresh like this through the growing season.
Cultivariable notes tuber formation only begins after the autumn equinox once days shorten to 12 hours or less -- a harvest like this depends on getting several weeks of that short-day period before the first hard frost.
Light: full sun in cool climates, partial shade where temperatures often exceed 80F; requires short days (12h or less) to initiate tuber formation, beginning after the autumn equinox. Soil: loose, light soil for easy harvest, tolerates poor soil, benefits from compost/organic fertiliser, pH 5.5-7.5 (optimal 5.5-7.0). Size: ~18in tall (often sprawls lower), 2-3ft spread, tubers 4-8in long, 1.5in wide. Hardiness/climate: best where summer highs stay below 85F with cool nights (low 70s F or cooler); survives to USDA zone 9a (20-25F) but most of that zone is too hot in summer; well suited to Pacific Northwest and coastal California. Planting: whole tubers 2-3in deep, 18in spacing between plants, 24-48in between rows; plant after final frost through August. Propagation: tubers, or stem/stolon cuttings rooted before tuber formation; seed has no dormancy and a short viable lifespan. Pests: voles cause significant tuber damage especially at harvest; tarnished plant bugs target flowers; wireworms cause mostly cosmetic tuber damage. Diseases: stem rot (lower stems blacken/soften), bacterial soft rot on tubers, "oca decline" symptom complex (knobbly tubers, early sprouting, reduced yields, fasciation), mild viruses including Papaya mosaic virus and unidentified potyviruses. Harvest: no earlier than early November, third week of November gives ~80% potential yield. Storage: 40F/4C at 90%+ humidity gives over a year of storage life; oca loses acidity in storage, lowest after 4-6 weeks at 70F.
Hardiness H2 (1-5C, tolerant of low temperatures but not surviving freezing). Soil: loam, sand, well-drained, acid/alkaline/neutral pH. Sun/aspect: full sun to partial shade, east/west-facing. Exposure: sheltered. Size: 0.1-0.5m height and spread, 2-5 years to maturity. Propagation: separate and replant tubers in autumn or spring. Pests: potentially vulnerable to vine weevil. Diseases: generally disease-free. Edible use: produces edible, fleshy, red or yellow tubers, grown as a food crop as well as ornamentally.
2 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
What problems affect ocas?
Our data links 4 diseases and 4 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.
Science-based growing guides · Thresholds that hold in any climate
This guide states the conditions the plant itself responds to — soil temperature, frost tolerance, day length — rather than dates, because the same calendar month means opposite seasons in the northern and southern hemispheres. Anything genuinely restricted to one part of the world is named as such rather than presented as universal. Written and maintained by our editorial team against international horticultural research and extension sources.
Sketch your exact plot shape, pick your crops, and get a spacing-accurate bed layout with companion pairings and a rotation plan. Spacing, companion pairings and rotation are the same in every climate and both hemispheres — pair the layout it gives you with when to plant to set your own timing from soil temperature.
