Photo: H. Zell — CC BY-SA 3.0 · source
Survives zone 3 through 7
Harvest calendar
Best planted in early spring after your last frost, or in fall before the ground freezes, depending on your climate.
Butternut is the true 'white walnut,' prized for its sweet, oily nutmeat, but it is now one of North America's most endangered trees — an introduced fungus, butternut canker, has killed the majority of wild trees since the 1960s with no cure available, making surviving canker-tolerant individuals and butternut × Japanese walnut ('buartnut') hybrids a conservation priority.
- Hardiness
- Zone 3–7
- Habit
- Tree
- Edible part
- Nut
- Ripens
- Sept–Oct
- Mature size
- Tree 12–20 m, wide-spreading — not containerable
- Light
- Full sun
- Soil pH
- 6.0–7.5 (near-neutral; lime-tolerant)
- Environment
- Temperate
- Native range
- Eastern North America, from New Brunswick and southern Quebec south through the Appalachians to Georgia and Arkansas, and west to Minnesota and North Dakota.
- Status
- Both wild and cultivated
- Years to fruit
- 5–10 yrs
- Growth speed
- Medium rate; reaches nut-bearing age in 6–10 years, comparatively fast for a walnut, though the tree itself is short-lived, rarely exceeding 80–90 years.
- Spacing
- 1100 cm (433 in) apart — about 121 m² (1302 sq ft) per plant
- Leaf shape
- Pinnately compound leaves 25–50 cm long with 11–19 oblong-to-lanceolate leaflets, each 5–13 cm long, finely serrated and downy on the underside.
- Root system
- Deep, carrot-like taproot growing straight downward — seedlings are intolerant of transplanting or root disturbance and should be set in a permanent position while young.
- Fruit description
- An oval, tan nut 4–6 cm long enclosed in a sticky, greenish, ridged husk, borne singly or in clusters of 3–5. The kernel is sweet and notably oily but makes up only about 20% of the seed's weight and is difficult to extract from the deeply corrugated shell.
- Propagation
- Grown from seed or by grafting. Sow ripe seed immediately in deep pots in a cold frame, protected from rodents, with germination in late winter to spring; seed stored dry over winter needs a period of cold stratification before spring sowing. Because wild populations are being lost to canker disease, grafting onto canker-tolerant selections or interspecific 'buartnut' (J. cinerea × J. ailantifolia) hybrids is increasingly used in restoration and breeding programs.
- Pollination
- Monoecious but HETERODICHOGAMOUS — a 2nd cultivar of the opposite type greatly improves set
The edible parts listed above are a starting point, not a field guide. Identify a plant with certainty — ideally against a local authority — before eating any part of it, and read the full disclaimer. Spotted something wrong? Report it.
Growing guide
Fertilizing. Prefers a deep, moist, well-drained loam rich in organic matter, with a slightly alkaline to neutral pH of roughly 6–8; tolerates both wet and dry soils but not compacted clay subsoils or shade. No unique feeding regime is documented beyond standard organic mulching — it is noted as a dynamic accumulator whose fallen leaves recycle minerals back into the soil.
How it spreads. Single-trunked, non-suckering tree with an open, rounded, spreading crown — it does not colonize by root suckers.
Growing tips. Critically threatened by butternut canker (Ophiognomonia clavigignenti-juglandacearum), a fungal disease discovered in the late 1960s that has killed over 80% of trees in numerous states and for which there is no cure — infected trees typically die within 5–10 years. The species is ranked vulnerable to critically imperiled across most of its range and is IUCN Red-Listed as Endangered; some foresters now advise against planting straight butternut and instead favor canker-tolerant 'buartnut' hybrids with Japanese walnut, the only documented source of meaningful resistance. It is a documented medium-level juglone producer, with an allelopathic zone reported to extend 18–25 m from the trunk, affecting tomatoes, potatoes, azaleas, and rhododendrons. It needs full sun and about 105 frost-free days to ripen its crop, is intolerant of shade or competition, and is comparatively short-lived for a walnut, seldom exceeding 80–90 years.
Companion planting. Like black walnut, documented to produce juglone in amounts enough to wilt and yellow sensitive nearby plants — keep it clear of apples, pears and blueberries.
Grow journal
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