Why You Should Grow Walnuts (Juglans regia)

If I were to tell you of an apocalypse proof asset that is 100% guaranteed to increase in value, both in the short (3yrs) and long term (300yrs), will contribute to your good health, provides aesthetic pleasure to your surroundings, has the potential to replicate itself exponentially and has parts that can be dipped into smooth melted dark chocolate, covered in cocoa powder and eaten, surely you'll be chuffed to learn that I'm referring to none other than Juglans regia - The Walnut tree.   

The walnut

Juglans regia is known by several common names including Persian walnut, common walnut, English walnut, Carpathian walnut and Madeira nut. The natural range of this plant is from the Carpathian mountains through the middle east and into the Himalayas.

Hardiness 

Walnuts from the middle east and the Persian strains, are hardy to zone 5 (-23°C) while the Carpathian strains can withstand temperatures as low as -32°C (zone 4). You can't grow these plants in the lower latitude areas without at least 500-1,500 hrs per year of temperatures below 7°C. At high latitude climate the young shoots and flowers are susceptible to frost damage in the spring, and early frosts in the autumn can cause damage to new shoots.

Description 

Walnuts are fast growing trees that develop broad canopies reaching 18m width and 30m in height. It is a light-demanding species, requiring full sun to grow well.

The buds awaken from winter dormancy in mid April - late May (depending on cultivar) and leaf fall occurs in early November. The large compound leaves give off a lemon / lime scent particularly when crushed. The flowers open before or around the same time as the leaves and you can find both male and female flowers on the plant (monoecious). The male flowers are slender catkins and the female flowers are smaller, often found on the tips of the branches. Pollination is carried out by the wind.

Pollination

Walnuts have both male and female flower parts on the same tree. The pollen is shed from the male flowers and should settle on the females flowers. The pollen is physically very small and light and can travel quite some distance. Studies have shown in certain orchards that wind blown pollen came from trees over a mile away.

If the pollen from the male flower settles on the female flower when they are receptive, fertilisation is likely to occur and the female flower will develop into nuts.

The time of pollen shedding from the male flowers does not always overlap well with the time of female flower receptivity to pollen. This condition is referred to as dichogamy. To overcome this problem growers can select another walnut cultivar (a pollinator), the male flowers of which open at the same time as the female flowers from the main cultivar. The pollinator should be situated upwind from the main crop. If you have other walnuts upwind from your site you should not have problems with this.    

Nearly all commercial orchards are co-planted with a pollinator variety to ensure the main crop gets enough pollen to set nuts. The recommendations for optimal pollination in an orchard environment is to plant one row of pollinators for every eight main crop rows and to plant the row of pollinators upwind.

Lateral Bearers

Lateral bearing cultivars bear fruits on lateral buds of shoots and are generally of higher productivity than terminal and intermediate bearers due to the larger number of fruit buds on these plants.

Terminal/Tip Bearers

Terminal bearing cultivars bear fruits on the tips of the shoots.