Walnut
Juglans regia
The walnut is a large, long-lived deciduous tree grown in Kashmir, Himachal and Uttarakhand for its nuts. It needs a cold winter, deep soil and plenty of space.
Photo: Thesupermat · CC BY-SA 3.0, via Wikimedia Commons
Essential Care Requirements
Light
Full sun
Watering
Moderate
Water deeply in dry summers, especially while nuts fill.
Soil
Deep, fertile, well-drained loam; pH 6.0–7.5.
Temperature and humidity
-20–35 °C · Moderate humidity
Feeding
Feed with compost and a balanced fertilizer in early spring.
Pruning and propagation
Propagate by grafting, seed
Prune in late summer, not spring, to avoid heavy sap bleeding. Keep a strong central framework.
The nuts are safe for people (though a common allergen). Mouldy walnuts are dangerous to dogs, and the green husks stain skin.
Top Cultivation Tips
Grafted trees bear in 4–5 years.
Collect nuts when husks split.
Dry nuts thoroughly in shade.
Plant well away from vegetable beds, as roots suppress some plants.
Common problems
Anthracnose
A fungal disease that causes dark, sunken spots on leaves, flowers and fruit, especially mango, chilli and papaya.
How to treat it →PestAphids
Small, soft-bodied insects that cluster on new shoots and buds, sucking sap and leaving sticky honeydew behind.
How to treat it →PestCodling moth
Caterpillars of a small moth that tunnel into apples and pears, leaving a hole and brown, frass-filled tunnels to the core.
How to treat it →PestScale insects
Immobile, shell-covered insects that cling to stems and leaves, draining sap and weakening trees and houseplants.
How to treat it →PestSquirrels
Bushy-tailed rodents that dig up bulbs and seeds, strip bark, and eat fruit, nuts and sweetcorn.
How to treat it →DiseaseStem canker
Sunken, dead patches of bark on stems and branches caused by fungi or bacteria, which can girdle and kill the shoot above them.
How to treat it →DiseaseZinc deficiency
A trace-element shortage that causes small, narrow, yellowing leaves bunched on short shoots, most often on alkaline or sandy soils.
How to treat it →
