Site selection and climate

• For successful cultivation of walnut, plain area with 20-degree slopy land is suitable.
• It can also be cultivated in bunds of field, grassland, public land & community forest.
• Walnut can resist slight frost & light snowfall however, heavy snowfall cause damage to trunk.
• High temperature during summer season is also not suitable for walnut tree. So, it can be cultivated successfully from 1000m to 2500m altitude from sea level.
• It requires annual 700 to 1500 hours chilling injury. Annual rainfall required is 760mm & above for successful cultivation.

Soil:

• Walnut requires well drainage facility, adequate moisture retaining deep soil upto 3 meters, rich in organic compounds, silty to clayey loamy soil.
• Optimum pH level for walnut is 6-7 for better production.

Orchard Layout:

• Walnut tree is large in size so, layout must be done with better consideration.
• Plant to plant distance is maintained 10 meter which assure 100 trees in a hector of land.
• Contour system is followed during layout of walnut tree. A frame can be used for drawing contour lines.

Propagation:

• Propagation through seed: It requires 7-8 years for flowering & fruiting.
• Vegetative propagation: Dormant bud is taken from previously fruiting tree in the mother rootstock plant (Hardey Okhar) to prepare sapling which are grafted. Rootstock of Hardey Okhar is taken & dormant bud of Dante Okhar is taken.

Planting:

• Walnut saplings are transplanted during Poush-Magh with the help of planting board to maintain sapling in the center of pit.
• Staking is necessary to ensure root stabilization.

Mulching:

• Mulching with grass straw or hay or paddy straw around 1-meter perimeter of plant with enough thickness is necessary.
• Do not cover the stem of sapling which can propagate insect & disease attack. Mulch helps is moisture maintenance & weed control.
• Clean the orchard repeatedly to make healthy growth of saplings. Apply 5-8 ml of glyphosate in 1 liter of water & spray in between the saplings to control the weed.

Irrigation:

• Irrigate the orchard immediately after planting saplings.
• Thick mulch helps in conserving moisture for longer duration, so during the early days of transplantation, moisture in the field must be carefully observed.
• After the fertilizer application, during flowering period, irrigation is mandatory.

Manuring:

• Apply fertilizer after pruning during the winter season. 1 doko FYM for non-fruiting tree while 2 dokos FYM for fruiting trees.

Training & pruning:

• Modified leader system & center leader system are followed in walnut tree for its training.
• Heavy pruning is not necessary in walnut however, during pruning special attention is required as its new flushes & flowering bud are present in tip of branches.
• Heavy pruning at the tip of branch can cause zero production.

Flowering & fruiting:

• Male & female flower occur at different branches in same walnut plant.
• Male flower occur in one year old branch in bunch hanging whereas female flower occur in new flushes in the tip of branches.
• Due to polyandry or different period of flower maturity in walnut tree.
• Cross pollination occurs that suggest to plant different cultivars in same orchard. Wind helps in pollination in walnut which ensure adequate fruiting.

Fruit maturity:

• Harvesting of walnut is done in Bhadra – Asoj month according to climate of Nepal.
• Fruit matures in different stages where outer covering is dehisced & fruit turn brown which indicates maturity stage.
• For synchronizing maturation of fruit, ethephon can be applied 15-20 days before fruit maturity.
• It is applied 200-500 ppm (0.2-0.5 ml/liter water) solution is applied all over tree.
• After harvesting moisture is maintained to 8% for long term storage & shipping.

Yield:

• Mature tree age is of 10-12 years in case of grafted tree while in seedling developed tree it is 15-20 years.
• At this stage, 150-200 kg/plant is obtained. However, average production is 40-50 kg/plant.