Manchurian walnut

Photo: Jean-Pol GRANDMONT — CC BY 2.5 · 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.

Manchurian walnut is the cold-hardiest of the commonly grown walnuts, native to the forests of Manchuria, the Russian Far East and Korea, and it is prized in breeding and rootstock programs for passing on cold tolerance and disease resistance to cultivated walnuts, alongside its own thick-shelled, oil-rich nuts.

Hardiness

Zone 3–7

Habit

Tree

Edible part

Nut

Ripens

Sept–Oct

Mature size

Large tree to about 25 m, broad-crowned — not containerable

Light

Full sun

Soil pH

6.0–7.5 (near-neutral; lime-tolerant)

Environment

Temperate

Native range

Native to Manchuria and adjacent northeastern China, the Russian Far East, and the Korean Peninsula, where it grows in mixed forests, mountain slopes and valleys, and along streams at elevations of roughly 500–2800 m.

Status

Both wild and cultivated

Years to fruit

5–10 yrs

Growth speed

Fast when young — among the quicker walnuts, slowing markedly after twenty years

Spacing

800 cm (315 in) apart — about 64 m² (689 sq ft) per plant

Leaf shape

Large odd-pinnate compound leaves 40–90 cm long, bearing roughly 9–19 (commonly 11–15) leaflets that are elliptic to ovate-elliptic or elliptic-lanceolate, 6–17 × 2–7.5 cm, with serrate margins, acuminate tips, and downy undersides; foliage has the characteristic resinous walnut scent when crushed.

Root system

Develops a deep taproot like other walnuts, giving mature trees good drought tolerance but making young plants intolerant of transplanting or root disturbance.

Fruit description

A rounded to oval nut roughly 3–4 cm across with an extremely thick, hard shell that makes the well-filled kernel difficult to extract; the oil content reaches up to about 52%, and the kernel is sweet and rich once picked out, though the oil turns rancid quickly once pressed.

Propagation

Grown from seed sown as soon as it is ripe, one per deep pot in a cold frame — germination typically follows in late winter or spring. Seed can also be held over winter in cool, moist conditions (such as a refrigerator's salad drawer) and given a period of cold stratification before an early-spring sowing. Because of its deep taproot, seedlings resent root disturbance and should be moved to permanent positions while young. It is also used in China and the Russian Far East as a cold-hardy rootstock and breeding parent for grafting cultivated walnuts.

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.