A seedbank stores seeds as a source for planting in case seed reserves elsewhere are destroyed. It is a type of gene bank. The seeds stored may be food crops, or those of rare species to protect biodiversity. The reasons for storing seeds may be varied. In the case of food crops, many useful plants that were developed over centuries are now no longer used for commercial agricultural production and are becoming rare. Storing seeds also guards against catastrophic events like natural disasters, outbreaks of disease, or war. Unlike seed libraries or seed swaps that encourage frequent reuse and sharing of seeds, seedbanks are not typically open to the public.
Orthodox seeds can be maintained in a dormant state for decades in a cool and dry environment, with little damage to their DNA; they remain viable and are easily stored in seedbanks, when suitably prepared; examples include many species in the families Solanaceae, Fabaceae and Poaceae. By contrast, recalcitrant seeds are damaged by dryness and subzero temperature, and so must be continuously replanted to replenish seed stocks. Examples include the seeds of cocoa and rubber.
Optimal storage conditions
Depending on the species, seeds are dried to a suitably low moisture content according to an appropriate protocol. Typically this will be less than 5%. The seeds then are stored at -18°C or below. Because seed DNA degrades with time, the seeds need to be periodically replanted and fresh seeds collected for another round of long-term storage.
- Stored specimens have to be regularly replanted when they begin to lose viability.
- Only a limited part of the world's biodiversity is stored.
- It is difficult or impossible to store recalcitrant seeds.
- There is a need to improve cataloging and data management. The documentation should include identity of the plant stored, location of the sampling, number of seeds stored and viability state. Other information, such as farming systems in which the crops were grown, or rotations they formed, should also be available to future farmers.[according to whom?]
- Facilities are expensive for third world countries which contain the most biodiversity.
- Many of the same issues apply to seed banks as with fallout shelters. With regards to its use as an insurance policy against cataclysmic events, it's highly questionable whether a seed bank would be at all usable in staving off starvation and societal collapse in almost any conceivable situation.[according to whom?]
In-situ conservation of seed-producing plant species is another conservation strategy. In-situ conservation involves the creation of National Parks, National Forests, and National Wildlife Refuges as a way of preserving the natural habitat of the targeted seed-producing organisms. In-situ conservation of agricultural resources is performed on-farm. This also allows the plants to continue to evolve with their environment through natural selection. An arboretum stores trees by planting them at a protected site.
Seeds may be viable for hundreds and even thousands of years. The oldest carbon-14-dated seed that has grown into a viable plant was a Judean date palm seed about 2,000 years old, recovered from excavations at Herod the Great's palace in Israel.
Recently (February 2012), Russian scientists announced they had regenerated a narrow leaf campion (Silene stenophylla) from a 32,000 year old seed. The seed was found in a burrow 124 feet under Siberian permafrost along with 800,000 other seeds. Seed tissue was grown in test tubes until it could be transplanted to soil. This shows how long DNA can be viable in the proper conditions 
There are about 6 million accessions, or samples of a particular population, stored as seeds in about 1,300 genebanks throughout the world as of 2006. This amount represents a small fraction of the world's biodiversity, and many regions of the world have not been fully explored.
- The Millennium Seed Bank Project housed at the Wellcome Trust Millennium Building (WTMB), located in the grounds of Wakehurst Place in West Sussex, near London, in England, UK. It is the largest seed bank in the world (longterm, at least 100 times bigger than Svalbard Global Seed Vault), providing space for the storage of billions of seed samples in a nuclear bomb proof multi-story underground vault. Its ultimate aim being to store every plant species possible, it reached its first milestone of 10% in 2009, with the next 25% milestone aimed to be reached by 2020. Importantly they also distribute seeds to other key locations around the world, do germination tests on each species every 10 years, and other important research.
- The Svalbard Global Seed Vault has been built inside a sandstone mountain in a man-made tunnel on the frozen Norwegian island of Spitsbergen, which is part of the Svalbard archipelago, about 1,307 kilometres (812 mi) from the North Pole. It is designed to survive catastrophes such as nuclear war and world war. It is operated by the Global Crop Diversity Trust. The area's permafrost will keep the vault below the freezing point of water, and the seeds are protected by 1-metre thick walls of steel-reinforced concrete. There are two airlocks and two blast-proof doors. The vault accepted the first seeds on 26 February 2008.
- The NSW Seedbank focuses on native Australian flora, especially NSW threatened species. The seedbank was established in 1986 as an integral part of the The Australian Botanic Gardens, Mount Annan. The NSW Seedbank has collaborated with the Millennium Seed Bank since 2003.
- Nikolai Vavilov (1887–1943) was a Russian geneticist and botanist who, through botanic-agronomic expeditions, collected seeds from all over the world. He set up one of the first seedbanks, in Leningrad (now St Petersburg), which survived the 28-month Siege of Leningrad in World War II. It is now known as the Vavilov Institute of Plant Industry. Several botanists starved to death rather than eat the collected seeds.
- The BBA (Beej Bachao Andolan — Save The Seeds movement) began in the late 1980s in Uttarakhand, India, led by Vijay Jardhari. Seed banks were created to store native varieties of seeds.
- Ellis, R. H., T.D. Hong and E.H. Roberts (1985). Handbook of Seed Technology for Genebanks Vol II: Compendium of Specific Germination Information and Test Recommendations. SGRP (System-Wide Genetic Resources Programme). Rome, Italy.
- Engels, J. M. M. and L. Visser (editors) (2003). A Guide to Effective Management of Germplasm Collections. CGN, FAO, GRST, IPGRI, SGRP.
- Kameswara Rao, N., J. Hanson, M. E. Dulloo, K. Ghosh, A. Nowell and M. Larinde (2006). Manual of Seed Handling in Genebanks. SGRP (System-Wide Genetic Resources Programme). Rome, Italy. 147 p.
- Koo, B., Pardey, P. G., Wright, B. D., et al. (2004). Saving Seeds. CABI, IFPRI, IPGRI, SGRP.
- Hong, T.D. and R.H. Ellis. 1996. A protocol to determine seed storage behaviour. IPGRI Technical Bulletin No. 1. (J.M.M. Engels and J. Toll, vol. eds.) International Plant Genetic Resources Institute, Rome, Italy. ISBN 92-9043-279-9 [www.cbd.int/doc/case-studies/tttc/seedstorage.pdf]
- National Geographic
- Frier, Sarah (2012-02-20). "32,000-Year-Old Plant Reborn From Ancient Fruit Found in Siberian Ice". Bloomberg.
- Drori, Jonathan (posted May 2009, filmed February 2009). "Why we're storing billions of seeds". TED2009. TED. Retrieved 2011-12-11.
- UK Millennium Seed Bank Project
- Work starts on Arctic seed vault
- Save the Seeds Movement of the Uttarakhand Himalayas, India