Classification
Product TypeRaw Material
Product FormIn Shell
Industry PositionPrimary Agricultural Product
Raw Material
Market
The U.S. in-shell walnut market is overwhelmingly a California market, with California's Central Valley producing more than 99% of the nation's walnuts. Harvest begins in late August and runs through late November, after which nuts are dried, sized, and routed into in-shell and shelled channels. The industry has about 4,000 growers and roughly 72 handlers, with many family farms and a concentrated packhouse layer. It is export-oriented, but stored inventory and domestic retail, foodservice, and food manufacturing demand keep the market active year-round.
Market RoleMajor producer and exporter
Domestic RoleCommercial retail and ingredient market with a large export surplus
SeasonalityHarvest runs from late August to late November; dried walnuts are stored and sold through the rest of the year.
Specification
Primary VarietyChandler
Secondary Variety- Hartley
- Howard
- Tulare
- Serr
- Vina
Physical Attributes- In-shell lots are sized as jumbo, large, medium, or baby under USDA standards
- Dry hull split signals harvest readiness
- Clean, well-dried nuts are preferred for storage and trade
Compositional Metrics- Target moisture is about 8% after air-drying
- Low moisture is important to prevent deterioration in storage
Grades- USDA in-shell sizing classes: jumbo, large, medium, baby
- Buyer-specific defect tolerance and quality standards
Supply Chain
Value Chain- Orchard establishment -> harvest -> hulling -> air-drying -> sizing -> packhouse grading -> storage -> domestic/export shipment
Temperature- Cool, dry storage preserves quality after drying
- Refrigeration or freezing helps keep walnuts fresh longer
Atmosphere Control- Low-moisture handling is important after hulling and air-drying
- The hull and shell provide natural protection on-tree
Shelf Life- Stored product can be held until needed, but heat and humidity accelerate deterioration
- Quality is best maintained at low moisture and cool temperatures
Freight IntensityMedium
Transport ModeSea
Risks
Climate HighBecause California's Central Valley supplies almost all U.S. walnuts, drought, heat, and water-allocation stress there can quickly cut yield and packout.Prioritize irrigation efficiency, water planning, and diversified sourcing within California.
Regulatory Compliance MediumDestination markets can require phytosanitary certificates, residue checks, and exact lot documentation; errors can delay or reject shipments.Pre-clear documents and test results against the buyer checklist before booking freight.
Food Safety MediumWalnuts are dried and stored nuts, so failures in drying, sanitation, or storage moisture control can damage quality and trigger buyer rejection.Verify drying to the target moisture level and keep storage dry, cool, and clean.
Market Volatility MediumThe crop is export oriented, so demand swings and tariff changes in key overseas markets can move prices quickly.Diversify destination markets and contract structures where possible.
Sustainability- Water stewardship in irrigated Central Valley orchards
- Soil health and orchard resource management
- Energy use in drying and storage
Labor & Social- Worker safety during orchard harvest and hulling
- Seasonal labor availability for harvest support
- Family-farm structure with a concentrated handler layer
Standards- Good Agricultural Practices (GAP)
- Good Manufacturing Practices (GMP)
FAQ
When is the California walnut harvest season?Harvest generally begins in late August and runs through late November.
How are in-shell walnuts sized for market?In-shell lots are commonly sized as jumbo, large, medium, or baby under USDA standards.
Why does drying matter for walnuts?Walnuts are air-dried to about 8% moisture so they store better and are less likely to deteriorate.
Where is most U.S. walnut production located?California's Central Valley grows more than 99% of the country's walnuts.