Home Wine Business Editorial Packaging Cork Harvest 101: Cork Supply Brings Harvest to Life on California Campuses

Cork Harvest 101: Cork Supply Brings Harvest to Life on California Campuses


The bark of a cork tree can only be harvested once every nine years,
so opportunities for such demonstrations are few and far between.

By Skyler Christie


On Tuesday, May 28, Cork Supply, an international leader in the cork industry, hosted an educational event on the Cal Poly San Luis Obispo campus. The event featured a live cork harvesting demonstration from Carlos and João Ferreira, two esteemed harvesters from Portugal. This was followed by a brief seminar with Cork Supply company leaders and Cal Poly President Jeffery Armstrong, providing a rare and valuable educational opportunity for university students. 

The event featured several prominent figures from Cork Supply, including Greg Hirson (global director of innovation), Frederico Mayer (purchasing director, raw materials), Monika Michalski (global marketing director), and Robert Rasmussen (marketing manager). Additionally, Dr. Matt Ritter, a botany professor and the director of the Cal Poly Plant Conservatory, helped to moderate, sharing his expertise on the cork oak trees and their ecological significance. 

Forest to bottle

Founded more than 42 years ago, Cork Supply prioritizes superior cork quality for the wine industry. This dedication includes pioneering quality standards in the cork industry and serving the U.S. wine market, embodying a legacy of excellence and innovation.

[Photo by Skyler Christie]

“At Cork Supply, ‘forest to bottle’ is our theme,” Michalski stated, explaining how Mayer travels with his team to inspect cork forests to uphold the highest quality standards. The company sources approximately 60% of its raw materials from Portugal and 40% from Spain. Ninety-nine percent of these materials are dedicated to cork production, repurposing bark with defects for technical wine corks through granulation and compression, as well as for cork flooring (among other applications). Even discarded scrap materials are used innovatively, being burned in biomass boilers to generate energy for its facilities, further highlighting its commitment to sustainability and efficiency. 

[Photo by Skyler Christie]

Cork Supply visited Cal Poly’s campus for the first time to harvest bark from three of the campus’s 30 cork trees Tuesday morning, marking a rare and significant occasion. The bark of a cork tree can only be harvested once every nine years, so opportunities for such demonstrations are few and far between. During the demonstration, the Ferreiras used traditional Portuguese axes to chop and pry off the bark while ensuring the trees remained unharmed. This ancient hand-stripping process has remained largely unchanged over centuries, highlighting the distinctive attributes of cork trees, known for their carbon-negative footprint and natural ability to regenerate bark over time. 

Cork’s lifetime sustainability

[Photo by Skyler Christie]

Exploring the life cycle of cork oak trees revealed their remarkable ability to regenerate bark post-harvest without compromising tree health. Initially, the bark harvested is unsuitable for premium wine corks, requiring several years to naturally thicken and smoothen for optimal cork quality. On average, a cork oak forest typically houses between 50 to 150 trees per hectre, each with the potential to produce approximately 1,500 natural corks. Beyond cork production, cork oak trees are impressive CO2 repositories, living up to 200 years and harvested every nine years following maturity, significantly drawing down greenhouse gas emissions throughout their lives.

The cork harvest, confined to select regions globally, remains unfamiliar to many despite its crucial role in wine production and packaging. Natural cork’s ability to enhance wine oxidation makes it far superior to substitutes such as synthetic corks and twist-off tops, which have gained popularity in recent years. This superiority was emphasized by campus activations aimed at localizing and specializing cork knowledge for California’s winemaking students.

Moreover, Cork Supply’s recent innovation, Legacy, exemplifies its dedication to advancing natural cork technology. Legacy’s development allows for the visualization of cork’s internal structure and understanding of its oxygen transfer properties. These advancements promise to significantly improve wine quality and aging processes.

Bringing harvest to life

Cork harvest at Cal Poly SLO campus
[Photo by Joe Johnston/University Photographer/Cal Poly]

Cork Supply’s initiative to engage with agricultural programs at universities across the United States through its cork masterclass program represents a pivotal effort to bridge gaps in enology education. Recognizing that cork is typically overlooked in the enology curriculum, Cork Supply’s masterclass aims to educate future winemakers on cork’s versatility and its role in the wine industry. Despite the logistical challenges of large-scale planting and harvesting of cork trees in the United States, Greg Hirson emphasized Cork Supply’s focus on education and awareness-building. While the industry’s core infrastructure remains in Portugal, Cork Supply is committed to disseminating knowledge about cork’s unique properties and capabilities worldwide.

Attending this event was an eye-opening experience that reaffirmed the importance of sustainable practices in the wine industry. Cork Supply’s commitment to quality, sustainability and innovation is paving the way for a greener future. As a graduating student entering the wine industry, witnessing these practices firsthand was both educational and inspiring. It highlighted how traditional practices, combined with modern sustainability efforts, can offer new solutions to major global challenges.


Skyler Christie

Skyler Christie

Skyler Christie was born and raised in Healdsburg, Calif., and is currently a senior at Cal Poly San Luis Obispo, majoring in agricultural business. Following graduation in June 2024, she will join the team at Sonoma County Winegrowers Commission as an assistant marketing manager. Simultaneously, she is preparing for the LSAT, with aspirations to begin law school in the fall of 2025.