Tree Species: Walnut (Juglans regia).

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Non-native. Native to the Balkans through Central Asia to the Himalayas. Introduced to Britain by the Romans for its nuts and timber. Now widely naturalised and cultivated.

Deciduous – leaves fall in autumn.

Leaves: Large pinnate leaves, 20–40 cm long, with 5–9 broad, oval leaflets. Terminal leaflet often larger. Leaves emit a strong aromatic smell when crushed. Arranged alternately.

Bark: Smooth and olive-brown when young, developing deep ridges and furrows with age.

Flowers/Fruit/Seeds: Separate male and female flowers on the same tree. Male flowers are long green catkins; female flowers are small clusters on current shoots. Produces large, green-skinned nuts containing a hard shell around the edible walnut kernel.

Overall shape: Broad, rounded crown with widely spreading branches. Often forms a commanding specimen tree.

12–15 m tall; spread often as wide as height.

5. Habitat & Range

Widely planted across the UK in parks, estates, orchards, and large gardens. Grows best in southern England in deep, fertile soils with warm summers. Struggles in exposed upland or cold, wet sites.

Large pinnate leaves with few broad leaflets (less numerous than ash or locust).

Strong resinous smell when leaves are crushed.

Large green-skinned nuts falling in autumn.

Spring: Leaves emerge late (after many other trees); male catkins appear.

Summer: Large green canopy casts deep shade.

Autumn: Green fruit husks split, dropping walnuts; leaves yellow and fall early.

Winter: Bare, with stout twigs and ridged bark.

8. Human Uses

Nuts widely eaten, used in baking, oil production, and liqueurs.

High-quality timber prized for furniture, veneers, and gunstocks.

Historically planted in farmyards as a shade and nut tree.

Leaves and roots produce juglone, a chemical that suppresses growth of nearby plants.

Nuts eaten by squirrels, mice, and birds.

Flowers provide pollen for insects, though less valuable than native trees.

Large canopy offers shade and shelter for wildlife.

In Roman times, walnuts were called “Jupiter’s acorns” (Jovis glans), giving rise to the name Juglans.

Walnuts were often thrown at weddings in Europe as symbols of fertility and prosperity.

Because of juglone, walnut trees were historically believed to “poison” the ground around them.

Best time to plant: Late autumn or early spring.

Soil: Prefers deep, fertile, well-drained loam; dislikes shallow chalk and heavy clay.

Light: Needs full sun for nut production.

Watering: Water regularly in first 2–3 years; benefits from moisture in dry summers.

Spacing: Allow 10–15 m between trees for full growth.

Aftercare: Mulch to retain soil moisture. Protect young trees from rabbits/deer. Minimal pruning required; prune in late summer to avoid bleeding.

Urban: Unsuitable for street planting due to size and dropping fruit; best for parks and large estates.

Garden: Excellent for large gardens and orchards; not suited to small plots due to shade, root chemicals, and large size.

Note: nuts are edible