California Walnuts

California Walnuts are the world standard for high quality, tasty walnuts. At Summerfield Farms we have a unique appreciation for walnuts as we carefully manage and oversee the first leg of their journey to you the consumer.  The California Walnut Board has some wonderful information about walnuts, including their history, how they are grown, and the best health reasearch dealing with walnuts. However, we would like to focus in on the growth of walnuts and provide some details of yearly on farm activities and services we provide as they pertain to the growth and production of California Walnuts. 


At Summerfield Farms we oversee all aspects of walnut production up to and including harvesting, hulling, and dehydrating. After being dehydrated our walnuts are shipped to buyers for commercial processing, which includes shelling and packaging, and then distributed to you the consumer. We pay careful attention to each aspect of our farm operation, following our established Good Agricultural Practices (GAP’s) in the production of our walnuts. Walnut production is a delicate dance; managing the quality of the orchard and therefore the walnut itself, working towards high yields without sacrificing orchard quality, all while utilizing sustainable and efficient management practices. We aim to be good stewards of our trees, our ground, our water, and most importantly our customers.

Planting / Orchard Development

Planting a walnut orchard begins well before a tree is ever placed in the ground. Selection of ground to be planted is key as is ensuring an adequate water supply and delivery system. Walnuts grow best in deep well drained soils. Soil and nematode samples should be taken and if neccessary corrective steps (fumigation, addition of soil ammendments) taken to adjust imbalances. Next a grower will select the best spacing for trees depending on variety/rootstock vigor and field conditions and select the type of tree to plant whether it is a grafted tree propogated at the nursery or a clonal tree progagated and grafted in the field. Finally the big day arrives and trees are planted either by hand or mechanically. But you’re not done yet. Young trees require special attention and have unique water and nutritional needs. Weeds must be managed, trees may need stakes depending on wind, and young trees should be painted to avoid sun damange. It is also critical to manage tree growth, pruning to vigor if necessary, to ensure an adequate tree and root structure to support a high quality and high yield walnut orchard. Starting off your walnut orchard correctly is the most important step to long term quality production, the best orchard management practices will always fall short if the orchard itself was not properly developed.

Orchard Management

However after planting and developing a new walnut orchard proper management of a walnut orchard is just as crucial to the production of high quality walnuts.

  • Immediately following harvest and into the winter months walnut orchards are pruned/ hedged to remove dead/sick wood and to stimulate growth and/or shape/reshape the tree to maximize sunlight interception for optimum growing conditions. Prunings are stacked and chipped in the orchard to reincorporate the organic material. This is also the time to “sanitize” the orchard to ensure all remaining unharvested nuts in the field are swept into the middle of tree rows along with leaves. This practice ensures insect pests inside the nuts are not carried over into the following crop year and allows organic material via the nuts and leaves to be mowed and incorporated back into the orchard soil.
  • Walnuts bloom, depending on variety and growing region, takes place from early April into May. Pollen is spread via the wind to receptive female flowers. It is common to apply scale or blight applications in this period as well as products that aid in pistillate flower receptivity (Serr variety). It is also common to apply a pre-emergent weed application in this window or earlier depending on upcoming rain events.
  • As walnuts begin to bloom and the nuts mature the orchard enters its period of nut growth. Irrigation begins and as the summer heat arrives it is critical to provide adequate deep moisture for walnuts to remain productive. Weeds must be managed and orchard floors mowed to maintain a level and clear orchard floor for the upcoming harvest. Walnut pests must be managed and if necessary applications made to ensure walnut yeilds are free of off grades. Walnuts also require fertilizer to ensure the tree is healthy and productive which in turn ensures the walnut is of the highest quality. Leaf and soil samples are collected and applications made. Nitrogen is an especially critical nutritional component. All fertilizer/chemigation applications (particularly nitrogen) are carefully logged and tracked to ensure sustainable management of groundwater resources.
  • Harvest Preparations take place in early August into September for different varieties. Any remaining weeds are managed, orchard floors are leveled, if necessary, and a final irrigation is done to reduce dust at harvest and set the orchard floor. Application of Ethephon, a product that moves forward the harvest timing and helps improve the quality and amount of walnuts harvested with the first shake, takes place.


Each year harvest arrives at a different time, dependant on winter chilling hours, spring bloom and the summer heat conditions. Typically walnut harvest in the Central Valley begins with the Ivanhoe or Serr varieties in late August or early September. The indicator of whether a walnut is ready to harvest is when the nut reaches the “packing tissue brown” stage which occurs when the packing tissue outside the nut kernel (inside the hull) turns a dark brown. Walnut trees are first shaken mechanically by shakers and walnuts rain to the ground. These walnuts are mechanically swept into “windrows” by two or more sweepers working in tandem to allow mechanical harvesters to pick them up. A crew of hand laborers also work to “push in the ends” of the field allowing the mechanized sweepers to easily access and move all the walnuts into the windrows. This crew will also remove larger sticks from the windrow. These conditioned windrows are picked up by a mechanical walnut harvester which also begins the process of removing sticks, leaves and debris in the field via cleaning chains and a suction fan.  Walnuts are then loaded by in-field elevators into truck trailers and transported to a Huller/Dehyrdator to be cleaned and dried.

Hulling & Dehydrating

Walnuts arrive from the field and travel through several different pieces of equipment designed to clean the walnuts and remove any debris from the field and moved through the Huller. The huller is designed to remove the “hull” the outer green flesh that grows around the exterior of the nut itself. Walnuts are then washed off with water and sorted electronically and by hand and then travel into bins. Once in bins walnuts are dried to an internal moisture content of 8%. Upon reaching this desired moisture content walnuts finish their time at Summerfield Farms and are loaded out into trailers and shipped to handlers for furthering processing, shelling, packaging and shipment to you, our valued walnut consumer!

This is a brief highlight of the various processes that take place at Summerfield Farms if you are interested in learning more detail or would like to enlist our services for your upcoming walnut crop please contact us. Additionally we greatly appreciate each of you that share our love of walnuts!