What is seed banking, and why does it matter?
Storing seeds in conditions that keep them viable for decades or centuries, as insurance against the loss of plant genetic diversity in the wild and in agriculture.
Why it is needed:
Crop genetic diversity has narrowed dramatically. Modern agriculture concentrates on a small number of varieties bred for yield and uniformity, and traditional landraces adapted to local conditions have been widely abandoned. Those varieties carry traits — drought tolerance, disease resistance, heat tolerance — that may be needed as conditions change, and which cannot be recreated once lost.
The vulnerability of uniformity is not theoretical. Genetically uniform crops are susceptible to a single pathogen or pest across an entire growing region, and historical epidemics — the Irish potato famine being the reference case — demonstrate the consequence.
Wild plant species are declining, including crop wild relatives that are a source of useful genes.
How it works. Seeds are dried to a low moisture content and stored at low temperature, conventionally around −18°C to −20°C. Under those conditions, metabolic activity nearly stops and viability is extended enormously. Samples are germination tested periodically, and regenerated by growing out and recollecting when viability falls — which is the resource-intensive part and the one that determines whether a collection stays alive.
The major facilities. The Svalbard Global Seed Vault is the best known — a backup facility inside a mountain in the Arctic, holding duplicate samples deposited by seed banks worldwide. It functions as a safety copy, not a working collection: material is withdrawn only by the depositor, and the first withdrawal was made to restore collections lost in the Syrian conflict.
The Millennium Seed Bank at Wakehurst focuses on wild plant species rather than crops.
The limitation that matters: not all seeds can be stored this way. Recalcitrant seeds — including many tropical trees, oaks, avocado and cocoa — do not survive drying and freezing. These require living collections, tissue culture or cryopreservation, all of which are far more expensive and vulnerable.
Ex situ conservation is complementary, not a substitute for protecting plants where they grow, since a seed in storage is not evolving with its environment.