edenhana

Walnut

A large, long-lived deciduous nut tree that performs best in New Zealand's drier regions and needs real space: standard trees can eventually reach 20-30m, though compact varieties bred for home gardens (e.g. 'Rex') top out around 12m. First nuts typically appear 4-5 years after planting, with full production by year 7-10. Walnut roots produce juglone, which suppresses the growth of many nearby plants (tomatoes and potatoes especially), so site it away from the vegetable garden. Develops a large taproot early, so choose the planting spot carefully - it doesn't transplant well once established. Walnut blight, a bacterial disease favoured by wet spring weather, is the main routine spray target for NZ growers.

Sun
full sun
Water
moderate
Spacing
800cm
Harvest
Ready in about 4-5 years
Difficulty
advanced
Grows in
Whangārei / Northland, Auckland, Hamilton / Waikato, Tauranga / Bay of Plenty, Gisborne, Napier / Hawke's Bay, New Plymouth / Taranaki, Palmerston North / Manawatū-Whanganui, Wellington, Nelson, Tasman, Blenheim / Marlborough, West Coast, Christchurch / Canterbury, Dunedin / Otago, Invercargill / Southland
Expected yield
10-20kg of nuts-in-shell per mature tree per season once fully established
Cost to grow
~$40 NZD
Grocery value
~$250 NZD
Mature height
12m
Evergreen
No, deciduous
Plants to avoid nearby
Tomatoes, Potatoes, Apples (walnut roots release juglone, a natural growth inhibitor toxic to many plants)
Common diseases
Walnut blight (bacterial), Crown rot (Phytophthora)
Common pests
Codling moth, Walnut blister mite, Leafroller caterpillar

When to plant by region

In Whangārei / Northland, Auckland, Hamilton / Waikato, Tauranga / Bay of Plenty, Gisborne, Napier / Hawke's Bay, New Plymouth / Taranaki, Palmerston North / Manawatū-Whanganui, Wellington, Nelson, Tasman, Blenheim / Marlborough, West Coast, Christchurch / Canterbury, Dunedin / Otago and Invercargill / Southland: June-July.

Growing stages

  1. Planting & establishmentBare-root, winter (June-July)

    • Develops a large taproot early and doesn't transplant well once established, so choose the planting spot carefully
    • Site well away from tomatoes, potatoes and apples; walnut roots release juglone, which suppresses growth in many nearby plants
    • Water regularly while young roots establish

  2. Early growthFirst 1-2 years

    • Check for codling moth, walnut blister mite and leafroller caterpillar on new growth
    • Standard trees can eventually reach 20-30m, though compact varieties like 'Rex' top out around 12m; factor this into placement early
    • Needs real moisture through summer to grow away strongly; irrigate during dry spells in drier growing regions

  3. Flowering & fruiting

    • Walnut blight, a bacterial disease favoured by wet spring weather, is the main routine spray target for NZ growers
    • Crown rot (Phytophthora) can develop if drainage is poor
    • First nuts typically appear 4-5 years after planting

  4. MaturityFull production by year 7-10

    • Established trees yield 10-20kg of nuts-in-shell per season once fully established
    • Continue watching for walnut blight in wet spring weather each year
    • Codling moth can still affect nuts on established trees

Similar plants