When to Plant Rhubarb in Cairns — Tropical Guide

Rhubarb

Photo: Wikimedia Commons

Rhubarb is a cold-climate perennial grown for its tart, colourful stalks used in pies, crumbles, jams, and sauces. It requires winter chill to break dormancy and performs poorly to dismally in tropical and subtropical Australia. CRITICAL SAFETY WARNING: Rhubarb leaves contain high concentrations of oxalic acid and anthraquinone glycosides and are TOXIC. Only the stalks are edible. Never eat the leaves.

Current Growing Conditions

Soil temperature: 25.2°C (optimal range: 10–25°C) ✗ Outside optimal range

How to Grow Rhubarb in Tropical Australia

When to Plant

NOT RECOMMENDED. Rhubarb requires winter chill to break dormancy and produce vigorous spring growth. Tropical zones do not provide this. Plants will be weak, leggy, and short-lived if they survive at all.

Soil
Deep, rich, well-drained soil loaded with compost and aged manure. Rhubarb is an extremely heavy feeder. Dig in generous amounts of organic matter before planting.
pH Range
5.5-6.8
Sunlight
Full sun in cool climates. Afternoon shade essential in warm-temperate and marginal zones. 4-6 hours minimum.
Spacing
90cm apart, 120cm between rows
Watering
Deep watering weekly during active growth (spring-autumn). Reduce to minimal in winter dormancy. Consistent moisture prevents stringy stalks. Drought stress causes thin, tough stalks.

Companion plants: Strawberry, Garlic, Onion, Beans, Brassicas

Avoid planting near: Dock (related weed, harbours pests), Rampant ground covers that compete

Tropical Growing Tips for Rhubarb

Key Challenges

  • No winter chill period for dormancy
  • Extreme humidity causes crown rot
  • Heat stress year-round
  • Plants will not thrive or produce worthwhile stalks

Pro Tips

  • Be honest with yourself: rhubarb will not succeed in tropical Australia
  • If you must try, treat as annual, grow from seed in the dry season, and expect disappointment
  • Consider alternatives like rosella (Hibiscus sabdariffa) which provides similar tartness in tropical climates

Harvesting Rhubarb

When ready: Stalks 25-40cm long, firm, and well-coloured (red, green, or pink depending on variety). Leaves fully unfurled. Stalks should snap cleanly when pulled.

How to harvest: PULL, do not cut. Grip stalk firmly at base and twist-pull outward with a slight twisting motion. Cutting leaves stubs that can rot and introduce disease to the crown. Remove leaf blade immediately (TOXIC - compost the leaves or discard, they are safe in compost). Never harvest more than one-third of stalks at once.

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