White Sage Seed Processing at Irvine Ranch Conservancy

Irvine Ranch Conservancy (IRC) is currently processing white sage (Salvia apiana) seeds, an essential step in preparing for upcoming restoration efforts across Southern California. White sage is a fundamental species in these projects, and its seeds are in high demand. Summer through early fall marks peak harvest season, as IRC works to build up seed inventory for winter and spring restoration.

White sage is a native evergreen perennial shrub found primarily in the coastal sage scrub habitats of Southern California and Baja California. It plays a vital role in local ecosystems, supporting a wide range of pollinators such as carpenter bees, Bombyliidae flies and hummingbirds. Its importance in the habitat and resilience make it a frequent choice for habitat restoration. 

The seed collection process begins at IRC’s Native Seed Farm. The IRC Plant Materials team works with volunteers and public participants to carefully harvest mature seed stems, placing them in specialized drying bags for at least a month. This drying phase is critical as it prevents mold, ensures the seeds don’t clog processing equipment, helps harden them for long-term storage and increases shelf life.

Once fully dried, the seeds undergo a multi-step cleaning process. Cleaning is essential to remove chaff, prevent contamination from weed seeds, and to minimize the space needed to store the seed in refrigerated storage.

• Thresher: A machine pulverizes the harvested material and uses airflow and special sized screens to separate seeds from plant material debris.
• Clipper: A second machine that further refines the separation, using smaller dual screens and airflow to isolate clean seeds.

The leftover plant material is repurposed as mulch for restoration site preparation.

Clean seeds are then stored in climate-controlled refrigeration units at the Native Seed Farm, alongside other native seeds. These units are equipped with dehumidifiers and housed in an enclosed area to minimize moisture. Once stored, seeds are ready for planting. IRC’s Habitat Restoration and Enhancement team will determine when and where, depending on what projects they are working on, however, it is typically timed with seasonal rainfall in the winter. 

White sage is harvested annually due to its frequent use in restoration projects. IRC staff continually monitor all inventory and prioritize species based on restoration needs. 

While trained staff handle the more intensive processing of white sage, volunteers are welcome to assist with the harvesting and processing of other plant species that require less specialized equipment. Interested in getting involved? Visit LetsGoOutside.org to learn more about volunteer opportunities and upcoming activities.