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iNaturalist — CC, credited & licensed per image
Juglandaceae family

Arizona Walnut Juglans major

Native
Drought-tough — Rated High for drought tolerance — a water-wise pick once it's established.
Deer-resistant — Low palatability to browsing deer. Usually passed over, but no plant is truly deer-proof when food is scarce.
USDA livestock toxicity rating — not a pet assessment. See the Toxicity detail further down for what's documented.
Also known as: Black Walnut

Arizona Walnut is a perennial tree native to the lower 48 states. It grows to 50 ft and blooms May in part shade – shade, with brown fruit. A keystone plant for native insects and the food web.

More about this plant

Juglans major, also known as Arizona walnut, is a walnut tree which grows to 50 ft tall (15 m) with a DBH of up to 0.61 metres (2 ft) at elevations of 300–2,130 m (1,000–7,000 ft) in Texas, Oklahoma, New Mexico, Arizona, and Utah. It also occurs in Mexico as far south as Guerrero. Common names include Arizona black walnut, and the Spanish name nogal cimarrón. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
USDA PLANTS — Sun · Soil & moisture
USDA — SoilPH — Soil pH
USDA PLANTS (DwCA, Zenodo 17903503) — Fertility Requirement / Soil Adaptation — Fertility need · Adapts to
USDA — Temp-Min °F — Hardiness
Niinemets & Valladares 2006 (CC0) — Drought tolerance · Shade tolerance · Wet-soil tolerance
Sun
Part shade – shade
Soil & moisture
Medium moisture
Soil pH
6–7
Fertility need
Medium
Adapts to
Coarse (sandy), Medium (loam)
Hardiness
USDA zone 4+
Drought tolerance
High
Shade tolerance
Low
Wet-soil tolerance
Low waterlogging
Size & form
Sources · Size & form
USDA PLANTS (DwCA, Zenodo 17903503) — Height, Mature — Height
Derived (allometric) — width = height × functional-class crown ratio fit on USDA Urban Tree DB · Tallo; method per Jucker et al. 2022, Pretzsch et al. 2015 — Mature width
USDA PLANTS (DwCA, Zenodo 17903503) — Planting Density (per acre) — Spacing
USDA PLANTS (DwCA, Zenodo 17903503) — Growth Rate / Spread / Growth Form / Lifespan / Active Growth Period / Seed Period — Spread · Growth rate · Growth form · Active growth
USDA PLANTS — Lifespan
TRY Plant Trait Database (CC BY 4.0) · USDA PLANTS — Foliage
USDA PLANTS (DwCA, Zenodo 17903503) — Fruit/Seed Color / Fruit Persistence — Fruit
Lifespan: USDA’s lifespan scale for trees: short = under ~100 years · moderate = 100–250 · long = over 250. Balsam fir and other short-lived conifers are genuinely short for a tree, not short like an annual.
Height
50 ft
Mature width
~ 30 ft wide DERIVED derived estimate — open-grown crown allometry (height × growth-form ratio); not a measurement
Spacing
7–21 ft apart from USDA planting density
Spread
None — clumping
Growth rate
Slow
Growth form
Single stem
Lifespan
Perennial · long-lived
Foliage
Deciduous broadleaf · coarse texture
Active growth
Spring & summer
Fruit
Brown persists into winter
In the garden
Sources · In the garden
USDA PLANTS (DwCA, Zenodo 17903503) — Propagation Method / Commercial Availability — Propagate by · In the trade
USDA PLANTS (DwCA, Zenodo 17903503) — Germination (cold stratification) — Seed starting
USDA PLANTS — Seed Period — Seeds ripen
USDA PLANTS (DwCA, Zenodo 17903503) — Foliage Texture / Browse Palatability / Resprout — Deer browsing · Resprouts if cut
Propagate by
Seed, Cuttings, Bare root, Container
Seed starting
Needs cold stratification a cold-moist spell before it germinates
Seeds ripen
Autumn – Winter seed-collection / harvest window
In the trade
Contract growing only
Deer browsing
Low often deer-resistant
Resprouts if cut
Yes regrows after top-kill
Canopy layer — Sits in the canopy of a layered food forest or polyculture.Open guide →
derived roles
AI = read by an AI vision model · DERIVED = a computed estimate, not a direct measurement. The “How we know this” section below details each.
The garden year bloom → fruit → fall colour
J
F
M
A
M
J
J
A
S
O
N
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Bloom
Fall colour
Bloom (the flower's colour) Fall colour
Bloom · May — USDA PLANTS (DwCA, Zenodo 17903503) — BloomPeriod
Fall colour · 506 obs · USA-NPN observed “coloured leaves” — timing varies by site & year
When to sow · for your area

Sow timing keys off your local last- and first-frost dates.

Species characteristics from USDA PLANTS (public domain) + TRY (CC BY) — general guidance, not a guarantee for your exact site. Deer "browsing" is documented palatability, not a deer-proof claim.

Wildlife & pollinators

How pollinator value is scored →
❧ Caterpillar hosts ~129 caterpillar species

Juglans supports ~129 caterpillar species.

Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is an exceptional genus.

Recorded feeding on Juglans in North America, including:

Antheraea oculea · Western Polyphemus Moth ✦ Citheronia splendens · Splendid Royal Moth ✦ Malacosoma californica · Western Tent Caterpillar ✦ Abagrotis alternata · Greater Red Dart Achatia distincta · Distinct Quaker Acrobasis angusella · Hickory Leafstem Borer
+ 8 more species →
Acrobasis caryivorella · Hickory Shoot Moth Acrobasis demotella · Walnut Shoot Moth Acrobasis indigenella · Leaf Crumpler Moth Acrobasis juglandis · snout moth Acrobasis juglanivorella · snout moth Acrobasis kearfottella · snout moth Acrobasis latifasciella · snout moth Acrobasis stigmella · snout moth
Keystone count (genus-level) from Warren II 2026 (CC0) · Tallamy host-use records. Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0). ✦ = recorded on this exact species.
Species thumbnails re-hosted from iNaturalist — Creative Commons, credited per image (hover for credit). Click any species to see it on iNaturalist. Not exhaustive; many taxa have no openly-licensed photo yet.
Frequently grows with

Across 40 U.S. vegetation-survey plots that recorded Arizona Walnut, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.

Alligator Juniper · 45% Ponderosa Pine · 45% Gambel Oak · 43% Squirreltail · 25% Sonoran Scrub Oak · 25% Canyon Grape · 25% Boxelder · 20% Sideoats Grama · 20%
"%" = share of this plant's plots that also held the species. From sPlotOpen → (Sabatini et al. 2021, CC BY 4.0) — open vegetation plots: wild community composition, not garden design.
How we know this (3) Methods & honest limits
Photosynthesis Direct fact

A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.

Kattge, J. et al. TRY plant trait database — Categorical Traits Dataset (2012).
Climate niche (heat tolerance & native rainfall) Derived

We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.

Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.

Realized-niche / climate-envelope approach (Pearson & Dawson 2003; Soberón 2007). Climate: NOAA NCEI nClimDiv county normals (1991–2020).
Mature width Derived

For woody plants that have a height but no measured crown, we estimate width = height × a crown-to-height ratio fit for that plant’s form (conifers narrower than broadleaf trees, shrubs widest), calibrated on our measured open-grown crowns and capped at the largest one ever measured. A measured crown always wins; herbaceous plants get nothing (no anchor).

Honest limits: A coarse class-median estimate for garden-scale spacing, not a measurement; woody single/multi-stem forms only.

Allometric basis: Jucker et al. 2022 (Tallo); Pretzsch et al. 2015; McPherson et al. 2016 (USDA Urban Tree DB).
Derived values are computed from open data by a published method — labelled, cited, and never shown as a direct observation. Full methodology →
Sources for this entry (36) Open & cited
[01] Scientific name & family — USDA PLANTS (DwCA, Zenodo 17903503)
[02] Growth habit & duration — USDA PLANTS (DwCA, Zenodo 17903503)
[03] Native status & distribution — USDA PLANTS (DwCA, Zenodo 17903503)
[04] Common name — USDA PLANTS (via GBIF)
[18] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[19] Wetland indicator — USACE National Wetland Plant List (2022)
[21] Description — Wikipedia (CC BY-SA)
[22] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[24] Conservation rank — NatureServe Explorer (CC BY)
[26] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[27] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[28] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[31] Other common names — Wikidata (CC0)
[32] Stress tolerance — Niinemets & Valladares 2006 (CC0)
[33] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[34] Caterpillar species — NHM HOSTS (CC0)
[35] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
Spot an error or have a better photo? Every field links to its source, and the whole dataset is open.
Cite this page Open data, please attribute

PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).

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