Walnut is a highly nutritious nut belonging to the Juglandaceae family, widely known for its rich content of omega-3 fatty acids, antioxidants, protein, and essential vitamins. Walnuts are consumed worldwide and are a key commodity in the global dried fruit and nut trade. The edible seed is enclosed in a hard shell and surrounded by a green husk during its growth period.
Walnuts play a crucial role in both culinary uses and the export economy of many countries. Due to growing global demand for healthy snacks, walnut export has become increasingly important in recent years. Major varieties dominating the global market include the American walnut, Chinese walnut, and Chilean walnut — each offering unique characteristics in terms of size, shell thickness, taste, and oil content.
Climate & Cultivation Conditions for Walnuts
Walnuts thrive in temperate climates with cold winters and warm summers. A chilling period is essential for proper bud break and fruit set. Ideal temperature ranges during the growing season are between 27°C to 32°C, while winter temperatures should be low enough (below 7°C) to fulfill the chilling requirement of 800–1500 hours, depending on the walnut variety.
Key growing conditions for walnut trees include:
- Soil: Deep, fertile, well-drained loamy soils with a pH between 6.0 and 7.5
- Sunlight: Full sunlight exposure for at least 6–8 hours per day
- Watering: Regular irrigation, especially during dry months; however, excessive moisture or waterlogging must be avoided
- Altitude: Best growth is observed at altitudes between 800 to 1800 meters above sea level
Countries like the United States (particularly California), China, Iran, Chile, and Turkey have developed large-scale walnut production and are major contributors to the global walnut export market.
Historical Background and Origin of Walnut
- The walnut (Juglans regia), also known as the Persian walnut or English walnut, has a rich and ancient history that dates back thousands of years. The origin of walnut cultivation can be traced to Central Asia and the Middle East, particularly the regions that now include Iran, Afghanistan, and parts of Eastern Turkey.
- Archaeological evidence suggests that walnuts were consumed by humans as far back as 7000 BCE. Ancient Persia (modern-day Iran) is widely considered one of the earliest centers of walnut domestication. In fact, the name Persian walnut reflects the historical importance of Iran in the early trade and cultivation of walnuts.
- From Persia, the walnut spread to Greece and Rome. The ancient Greeks referred to it as the “Royal Nut,” and the Romans helped distribute the walnut tree throughout Southern Europe. Later, walnuts were introduced to China via the Silk Road and eventually made their way to South Asia and the Himalayan regions.
- In the 18th century, Spanish missionaries brought the walnut tree to the Americas, especially to California, which today is the largest producer and exporter of walnuts in the world. Since then, American walnuts, particularly the Chandler variety, have become the global standard for high-quality export.
Summary of Key Regions in Walnut History:
| Region | Role in Walnut History |
| Iran | Origin and early domestication of Persian walnut |
| Central Asia | Native growing areas (Afghanistan, Kyrgyzstan, etc.) |
| Greece & Rome | Early spread through Mediterranean civilizations |
| China | Adopted via Silk Road; now a major producer |
| Chile | Newer player with high-quality export focus |
| USA (California) | Industrialized production and breeding leader |
Major Export Varieties of Walnut
The global walnut market is dominated by a few key varieties that are preferred in international trade due to their quality, kernel yield, and processing suitability. The most commercially important types of export walnuts include:
1. American Walnut (Juglans regia – USA)
The American walnut, mainly produced in California, is considered the gold standard in the global market. These walnuts are known for their light-colored kernels, mild flavor, thin shells, and high oil content. The U.S. is the world’s largest exporter of walnuts, offering both in-shell and shelled products.
2. Chinese Walnut
Chinese walnuts are widely cultivated in various provinces, including Yunnan, Xinjiang, and Shaanxi. They generally have thicker shells and darker kernels compared to American varieties. While domestic consumption in China is high, the country also plays a significant role in global walnut exports, especially to Asia and the Middle East.
3. Chilean Walnut
Chilean walnuts are gaining popularity due to their light color and freshness, as the Southern Hemisphere harvest occurs six months apart from the Northern Hemisphere. Chile exports high-quality in-shell and shelled walnuts, primarily to Europe, the Middle East, and India. Their competitive advantage lies in counter-seasonal production and consistent quality standards.
Global Production and Export Statistics
China
- Production: Approximately 1.1 to 1.3 million metric tons annually
- Export: China exports around 60,000 to 80,000 metric tons, mainly in-shell walnuts, but the majority is consumed domestically
- Key Export Destinations: Pakistan, UAE, Kazakhstan, Vietnam
United States (California)
- Production: Ranges between 620,000 to 720,000 metric tons per year
- Export: Roughly 60% of total production is exported, which equals about 350,000 to 420,000 metric tons
- Top Export Markets: European Union, Turkey, India, Japan, United Arab Emirates
Chile
- Production: Around 180,000 to 200,000 metric tons annually
- Export: Over 90% of production is exported, making Chile one of the most export-oriented walnut producers (approx. 160,000 to 180,000 metric tons)
- Major Markets: Germany, Italy, Turkey, India, Brazil
Varieties of Export Walnuts by Country
American Walnut Varieties (California)
The United States, especially California, is home to some of the most well-bred and commercially viable American walnut varieties. These cultivars are selected based on high kernel percentage, ease of cracking, light color, and resistance to pests.
Most common American walnut cultivars:
- Chandler – The most widely planted variety; known for its light kernel, high yield (up to 60% kernel recovery), and late leafing (which avoids spring frost).
- Hartley – Traditional variety with large nuts and high shell integrity; commonly exported in-shell.
- Howard – Excellent kernel quality and upright tree structure; suitable for high-density orchards.
- Tulare – High productivity, strong shell, and moderately light kernel color.
- Vina – Early to mid-harvest; medium-sized nut, dark kernel color, mostly used domestically.
These varieties dominate the American walnut export industry, particularly Chandler, due to its premium appearance and shelf life.
Chinese Walnut Varieties
Chinese walnuts are cultivated in diverse regions, resulting in multiple local cultivars with varying shell thickness, oil content, and kernel size. Most Chinese walnuts are hard-shelled and smaller, but several improved varieties are now grown for export.
Major Chinese walnut types:
- Xinjiang Thin-Shelled Walnut – Grown in Xinjiang province; popular for its relatively easy cracking and sweet flavor.
- Yunnan Iron Walnut (Tiepi Hetao) – Very hard shell, traditional variety; mostly used domestically.
- Zhaotong Walnut – High oil content and widely cultivated in Yunnan province.
- Shanxi Paper-Shell Walnut – Thin shell, high kernel recovery; increasingly used in Chinese walnut exports.
- Wen 185 (Wenyi 185) – Improved hybrid with thin shell, high yield, and lighter kernel; gaining popularity in export markets.
Chilean Walnut Varieties
Chile’s walnut production focuses on high-quality export varieties with light kernels and consistent sizing. Because of Chile’s counter-seasonal harvest, many buyers prefer Chilean walnuts for off-season supply.
Leading Chilean walnut cultivars:
- Chandler – Imported from California, now widely planted in Chile; known for high quality and yield.
- Serr – Early-bearing tree, good shell integrity, and mild taste; commonly used in both in-shell and shelled forms.
- Franquette – Late-leafing French-origin variety; less common but valued for premium markets.
- Pedro – Suitable for cooler areas, smaller nut size, moderate yield.
- Fernor – Recently introduced French variety; disease-resistant and cold-tolerant, increasingly adopted by Chilean growers.
Chilean walnut exports are dominated by Chandler and Serr, which meet the high-quality standards required by European and Middle Eastern markets.
Types of Walnut Kernels in the Export Market
Walnut kernels are the edible part of the walnut and are a key product in international trade. They are graded based on color, size, shape, and quality. Exporters and buyers worldwide classify walnut kernels according to standard categories defined by international trade norms, particularly those used by the U.S., Chile, and China.
By Color (Most Common Classification in Exports)
- Extra Light (EL)
- Very pale ivory or cream color
- Premium grade used in high-end food applications
- Common in American walnut exports (Chandler kernels)
- Light (L)
- Light tan or golden color
- Most popular grade in global markets
- Ideal for confectionery, baking, and retail packaging
- Light Amber (LA)
- Medium brown color
- Slightly lower grade, used in processed foods and snacks
- More common in Chinese walnut exports
- Amber (A)
- Darker brown shade
- Lowest grade, used for oil extraction or industrial purposes
By Shape
- Halves
- Whole walnut halves, preferred in premium packaging
- Most valuable form in walnut kernel exports
- Quarters
- Split into four even pieces; used in baking and bulk supply
- Broken Pieces
- Irregular fragments of various sizes (also called “chips” or “crumbs”)
- Suitable for cooking, bakery products, or granola mixes
- Walnut Meal
- Ground or powdered kernels, mostly for industrial food use or baking mixes
By Processing Type
- Raw (Natural) Walnut Kernels
- – Untreated, unroasted; commonly exported for reprocessing or retail sale
- Roasted Kernels
– Lightly baked for enhanced flavor; often packed for snacks
- Vacuum-packed Kernels
– Long shelf life and freshness preserved for export shipments
Usage of Different Kernel Types
- Extra Light Halves – Used in luxury packaging, chocolate coating, and export gift boxes
- Light Quarters and Pieces – Common in trail mixes, cookies, and energy bars
- Amber Kernels or Meal – Used in walnut butter, sauces, or oil extraction
Walnut Planting and Harvest Seasons
The walnut tree (Juglans regia) is a deciduous species that follows a distinct seasonal growth cycle, which is crucial for determining planting, care, and harvest times. The timing may vary slightly depending on the climate, region, and hemisphere, but overall, the cycle is similar across major walnut-producing countries.
Planting Season
Walnut trees are usually planted in late fall or early spring, when the tree is dormant and environmental conditions are favorable for root development.
- Northern Hemisphere (e.g., Iran, USA, China):
- Optimal Planting Time: November to March
- Fall planting (November–December) is preferred in regions with mild winters.
- Spring planting (February–March) is more common in colder areas with risk of frost.
- Southern Hemisphere (e.g., Chile):
- Optimal Planting Time: June to August (during local winter)
- Planting is timed to establish roots before spring growth begins in September.
Harvest Season
Walnuts are harvested once the outer green husk begins to crack and split, signaling maturity of the nut inside.
- Northern Hemisphere:
- Harvest Time: Late September to early November
- In the U.S. (California), harvest typically starts mid-September and continues through October.
- In Iran and China, harvest also begins in late September depending on elevation and climate.
- Southern Hemisphere (Chile):
- Harvest Time: March to May
- Because seasons are opposite, Chilean walnuts hit the market when Northern Hemisphere stocks are low — giving Chilean walnut exports a competitive advantage in off-season supply.
References
California Walnut Commission. (n.d.). Walnut varieties and industry overview. Retrieved July 20, 2025, from https://walnuts.org
ChileNut. (2024). Walnut production and export statistics. Retrieved July 20, 2025, from https://chilenut.cl
FAO. (2024). Ecocrop database – Juglans regia (Walnut). Food and Agriculture Organization of the United Nations. Retrieved July 20, 2025, from https://www.fao.org/ecocrop
FAO. (2023). FAOSTAT: Crops and livestock products. Food and Agriculture Organization of the United Nations. Retrieved July 20, 2025, from https://www.fao.org/faostat
INC (International Nut and Dried Fruit Council). (2024). Walnut kernel standards and classifications. Retrieved July 20, 2025, from https://www.nutfruit.org
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Zohary, D., & Hopf, M. (2000). Domestication of plants in the Old World (3rd ed.). Oxford University Press