The walnut pages on this site include listings of walnut nurseries, growers, sales as well as industry overviews, propagation information, walnut products and a range of other walnut related information.
Of the 1.5 million tonnes of walnuts produced globally per year, the USA and China are the two major producers. USA (California) is the major exporter and while China is a significant producer. Other countries exporting walnuts include France, Turkey, Chile, Italy, India, Romania, Mexico and Spain. While China is close behind the US in total production, there is a question whether it will remain a net exporter with internal consumption rising to meet total production.
The walnut is grown commercially in Tasmania, Victoria, New South Wales. Smaller orchards are located the Adelaide Hills and Riverland regions of South Australia and in south-west Western Australia.
Australian Walnut Industry
Australian Walnut Industry Association (AWIA)
Consultancy Service (Victoria)
Walnut trees can grow to 25 metres and live up to 200 years. They require a Mediterranean climate but with the inclusion of of a chilling period of 600 - 800 hours below 10°C. Walnut trees don't like frosts mid to late spring (flowering period), nor do they like the temperature to get too hot in summer (I'm a bit the same). The growth of walnut trees may be slowed down if they are located in a windy exposed position.
There's an old adage that waluts will grow where apples grow. Traditional soil requirements for walnuts are that it is deep and well drained. A pH greater than 6.0 suits walnuts. More recently walnut trees have been grown commercially in shallow soils that have previously been previously been ripped, hilled and had gypsum and lime added to the soil (Tatura hedgerow system). Nutrients need to be well balanced. It is recommended that a soil analysis and site/variety research be carried out early in the planning stage of developing a walnut orchard.
Traditionally walnuts were planted on a 16m x 16m grid 940 trees per hectare. Under the "Tatura' system walnut trees have been grown as close together as 6 metres between rows and 3 metre intervals - again expert advice should be sought. Trees are best planted late winter and early spring. Mulching and weed control are important.
The Black Walnut and Butternut walnut are natives of North America. These two varieties have thicker shells than the standard European walnuts. For walnut production, Black Walnut (Juglans niger) seeds or seedlings are often used as the rootstock from which commercial walnut varieties are grafted. J.regia is often used as rootstock for well drained soils while J. niger is sometimes preferred for wetter soils.
Although modern high yielding varieties of walnut trees bear fruit quite early in their lives, it is not until really deemed a harvest until about year 4 - 6. At around year 11 or 12 a walnut tree is in full production.Walnuts are wind pollinated and strategic planting of complimentry varieties will assist with pollination. Wallnuts make wonderful long lived shade trees in a large garden.
Harvesting and Processing
Harvesting of walnuts occurs around mid April each year. Timing of the season will be influenced to a degree by the variety grown, location and climatic conditions. Walnuts are usually mechanically shaken from the tree, swept into a windrow and picked up by a harvester. If conditions are damp they need to be picked up on a daily basis.
Walnuts are then hulled to remove the fleshy shell casing and cleaned and dried as quickly as possible. The moisture level is reduced from around 25% to around 8 - 10%. This usually takes around 2 weeks. For the home garden walnuts can be dried on racks but for commercial purposes a means of assisted drying is required.
Health and Nutrition
Walnuts are very high in Omega 3 and in monounsaturated oils. They are also contain a wide range of minerals and vitamins. See the Walnut Health and Nutrition page for details.
Photo right: Wellwood Walnut Oil
For a description of a selection of varieties available in Australia see Walnuts ( Harold H. Adem, DPI Tatura).
Wandiligong Nut Festival 2010.
Collecting walnuts - Courtesy of the Australian Walnut Industry Association.