Conservation Seed Bank

The Santa Barbara Botanic Garden’s Conservation Seed Bank safeguards more than 500,000 seeds for long-term extinction prevention. The collection includes more than 700 accessions representing more than 200 different kinds of native plants. The focus of the collection is rare plants from Central California, with a special emphasis on the Central Coast and the Channel Islands, but collections range from Northern California to the Nevada border to Baja California, Mexico. Requests to access these collections for authorized research, recovery or reintroduction purposes can be made to the Rare Plant Biologist

The Santa Barbara Botanic Garden Conservation Seed Collection

From the field to the freezer: safeguarding plant diversity for the long-term

Like the garden itself, a seed bank is a living collection. Although they seem small and inanimate, seeds are full of potential—small packages of genetic information encapsulated in dormant embryos. Depending on the species and the conditions following dispersal, seeds can either generate new plants in the next growing season, or lie in wait in the soil for the right combination of cues before germinating. Because of their small size and big potential, seeds are an economical way to safeguard plant diversity over the long-term. But, when it comes to long-term storage, not all seeds are created equally.

Long-term seed storage under frozen conditions requires an understanding of the biology of a species and the seeds that it produces. For simplicity, most seeds are classified as either “orthodox” or “recalcitrant.” Orthodox seeds have characteristics that make them well suited to conservation seed banking: natural long-term dormancy, toleration of drying, longer lifespan under frozen conditions. Many of California’s plants produce orthodox seeds that are designed to live in the soil seed bank until the right combination of germination cues stimulate germination. Natural long-term dormancy is often associated with plants that grow in unpredictable climates, like our Mediterranean climate where rain is not guaranteed every year. Some plants, like fire-followers, wait as seeds in the soil for the many years between fires. Orthodox seeds are built to last. In contrast, recalcitrant seeds have naturally short lifespans, do not tolerate drying and do not survive freezing temperatures. The seeds of oak trees are one example of an iconic California plant group that produces recalcitrant seeds. Because they cannot be stored in seed banks, these species require special attention and different conservation strategies. Inclusion in living collections at places like the Garden is one way that conservationists protect genetic diversity for these species.

The Conservation Seed Bank at the Garden is a Center for Plant Conservation certified regional seed bank, meaning that the Garden adheres to national and international best practices for conservation seed banking. The journey from the field to the freezer starts with research, identifying target plants, learning about their life cycle and reproduction, and selecting potential collection sites. We must then obtain all necessary permits and landowner permissions to conduct the work. In the field, our Rare Plant Conservation Team makes at least two visits to each site per year: once during the flowering period to survey, collect data, and collect herbarium specimens, and again to collect seeds. Seeds are collected by maternal line, meaning that the seeds of each individual plant are kept separately. This preserves information about genetic diversity among individuals and also allows us to make deliberate decisions about how to use seeds for restoration and reintroduction in the future. Following collection, seeds are cleaned and curated. If you peer through the window into the multipurpose lab in the Pritzlaff Conservation Center, you might observe staff and volunteers cleaning seeds. This work is especially active in the fall and winter. After cleaning, seeds are dried down to low humidity to prevent damage during freezing. Finally, the seeds are sealed in pouches and frozen at -20°C (-4°F) in our Conservation Seed Bank.

While the core mission of conservation seed banks is to provide for long-term conservation, these active, living collections are designed to be used for research, restoration or reintroduction before they perish in the freezer. Over time, seeds are periodically tested for viability and decisions are made about when to replenish the collection. Do not be fooled by an unassuming chest freezer - our Conservation Seed Bank is a localized biodiversity hotspot that plays an integral role in advancing the conservation and recovery of California’s rare plants every day!

If you are interested in learning more about our Conservation Seed Bank or are interested in sponsoring a collection, please contact our Rare Plant Biologist.