When to Plant Walnut in Brisbane — Subtropical Guide
Photo: Wikimedia Commons
Large deciduous nut tree that needs cold winters (500-1000+ chill hours) and warm dry summers. One of the best nut trees for cool-temperate and cold-highland Australia. Beautiful timber tree and shade tree. Important: walnut trees produce juglone, a chemical toxic to many plants grown nearby (allelopathy). Long-lived (100+ years). English walnut (J. regia) is the eating nut; Black walnut (J. nigra) used as rootstock and for timber.
How to Grow Walnut in Subtropical Australia
When to Plant
Not recommended. Insufficient chill.
- Soil
- Deep, fertile, well-drained. Walnuts have deep tap roots and need minimum 2m soil depth. Reasonably tolerant of clay but must not be waterlogged.
- pH Range
- 6.0-7.5
- Sunlight
- Full sun.
Companion plants: Grass (tolerant of juglone)
Avoid planting near: Tomato, potato, pepper, eggplant (juglone sensitive), Apple trees (some juglone sensitivity), Azalea, rhododendron (juglone sensitive), Any plant within root zone that is juglone-sensitive
Subtropical Growing Tips for Walnut
Key Challenges
- Insufficient chill hours
- Humidity drives blight
Pro Tips
- Walnuts are not suited to subtropical climates. Insufficient winter cold for proper dormancy.
Harvesting Walnut
When ready: Green husk cracks and separates from shell. Nuts begin to fall from tree. Shake branches to accelerate harvest.
How to harvest: Collect fallen nuts. Remove any remaining husk (stains hands - wear gloves). Dry in single layer in shade for 2-3 weeks until shell interior walls are dry.
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