Black Walnut

Black Walnut (Juglans nigra) is a large deciduous shade tree for properties with room to give it. In Australian gardens it settles at around 12m tall and 8m wide, with a broad canopy that turns warm yellow before the leaves drop. Mature trees carry edible nuts inside thick green hulls, and this is an acreage tree rather than a suburban courtyard choice.

Why you'll love it

• Deep shade, sooner than most. It is a fast grower in good soil, so a young tree casts useful shade within a few seasons.
• Nuts worth waiting for. The kernels are rich and strongly flavoured, and a well grown tree usually starts producing in its second decade.
• Reliable autumn colour. Foliage turns clear yellow late in the season, and the bare winter branch structure is handsome in its own right.
• Genuinely tough. Frost hardy, drought tolerant once established, and comfortable with heat and wind, which suits inland and exposed blocks.

Where it works best

Acreage and large gardens. Allow at least 10m of clear space around the trunk, because at 8m wide the canopy reaches further than most people expect and the roots spread wider still.

Shade over open ground. A single tree in a paddock or along a back boundary shelters stock and lawn through summer, and asks for no irrigation once it is away.

Not for mixed garden beds. The roots release juglone, a natural compound that suppresses many other plants. Keep vegetable beds, tomatoes and sensitive shrubs outside the canopy line.

Growing Black Walnut in Australia

Position and climate. Full sun and open ground. It belongs in cool temperate, warm temperate and Mediterranean gardens, where winters are cold enough to give it a proper dormancy.

Soil. Deep, free draining soil suits it best, though it copes with heavier ground provided water moves through. Young trees send down a strong taproot, so prepare a generous hole and avoid disturbing the root zone afterwards.

Water and feed. Deep soak weekly through the first two summers, then taper off as the roots go down. A complete slow release fertiliser in early spring is plenty, since heavy feeding pushes soft growth rather than a stronger frame.

Pruning. Shape to a single straight leader in the early years and lift the lower limbs for clearance. Prune in late summer rather than winter, because walnuts bleed sap heavily when cut while dormant.

What to expect when it arrives

We sell it in a 300mm pot, a 45L and a 100L. The 300mm and 45L trees are young, single stemmed whips with side shoots, and they establish fastest. The 100L is a heavier tree with real trunk calliper for presence on day one. Being deciduous, stock sent through winter arrives bare, which is normal.

Trees travel upright and are delivered Australia wide, with delivery from $29.95. Advanced and large stock is freighted at cost. Expect quiet progress in the first season, then strong extension growth from the second spring, backed by our 30 day healthy plant guarantee.

Plant care guides and related reading

• How to choose a canopy tree for shade
• Browse the full deciduous tree range
• Other edible trees and plants
• Trees and shrubs with autumn colour

Common questions

How far from the house should I plant it?

At least 10m from buildings, paving and services. The roots travel further than the canopy, so crowding it against a fence or driveway causes problems later.

How long before it produces nuts?

Usually into its second decade. Nut set improves when a second walnut stands within pollination range, so growers after a crop often plant a pair.

Will it grow in Brisbane or the tropics?

No. It needs the colder winters of cool temperate, warm temperate and Mediterranean districts. In humid subtropical and tropical gardens it sulks and rarely crops.

Is it safe around dogs?

Not entirely. Fallen hulls and nuts, particularly once they have gone mouldy on the ground, are hazardous to dogs. Rake beneath the tree through autumn if your dog scavenges.