A seed bank, also called a seed vault, stores seeds to keep different types of plant genes safe. This makes it a type of gene bank. There are many reasons to store seeds. One reason is to save the genes that plant breeders use to improve crops, such as increasing food production, making plants more resistant to disease, helping plants survive dry conditions, improving nutrition, and enhancing taste. Another reason is to help stop the loss of different plant genes in rare or threatened species, which protects the variety of life outside their natural habitats. Many plants that humans used long ago are now used less often; seed banks help keep the history and culture connected to these plants. Seeds stored in seed banks are kept at very low temperatures and low moisture levels to protect them from being lost. These seeds are safer than plants grown in natural environments or in fields, which can be harmed by natural disasters, disease, or war. Seed banks are sometimes called seed libraries because they hold important information about how plants have adapted to survive stress. They can also be used to create new types of seeds through genetic changes. The work of seed banks often lasts for many years, even hundreds of years. Most seed banks are supported by public funds, and the seeds are usually available for research that helps people.

Storage conditions and regeneration

Seeds are living plants, and keeping them healthy for a long time requires controlling the amount of moisture and temperature during storage. As seeds grow on the parent plant, many develop the ability to survive drying. These seeds, called "orthodox" seeds, can live longer if stored in a dry, cold environment. The exact dryness and coldness depend on how long the seeds need to be stored and how much money is available to build storage facilities. In the 1950s and 1960s, a scientist named James Harrington created practical rules for seed storage, called "Thumb Rules." One rule, called the "Hundreds Rule," says that the total of the air’s humidity and the temperature (measured in Fahrenheit) should be less than 100 for seeds to survive five years. Another rule states that reducing the water in seeds by 1% or lowering the temperature by 10 °F (5.6 °C) can double how long the seeds stay alive. Research from the 1990s showed that drying or cooling seeds too much can harm them, so these steps must be done carefully.

To help seeds stay healthy for many years, the Food and Agriculture division of the United Nations and a group called Bioversity International created storage standards for seed banks worldwide. These guidelines suggest drying seeds to about 20% humidity, placing them in high-quality, moisture-proof containers, and storing them at −20 °C (−4 °F). These conditions are often called "conventional" storage methods. Seeds from important crops like corn, wheat, rice, soybean, pea, tomato, broccoli, melon, sunflower, and others are stored this way. However, some seeds cannot survive the dryness or cold of conventional storage. These seeds, such as those from citrus fruits, coffee, avocado, cocoa, coconut, papaya, oak, walnut, and willow, must be stored using extremely cold temperatures, a method called "cryogenic" storage.

Over time, all seeds eventually lose their ability to grow. It is difficult to know exactly when this happens, so most seed banks regularly check how well seeds can germinate. If the germination rate drops below a certain level, the seeds must be planted, and new seeds must be collected for future storage.

Some seed banks may use simpler storage methods if their goal is only to keep seeds for yearly use and reduce costs for farmers in a specific area.

Challenges

Seed banks face a major challenge in choosing which seeds to collect. Collections must be useful by offering genetic diversity that people can access. They must also avoid collecting the same seeds multiple times to save resources.

Storing seeds for hundreds of years is another challenge. Orthodox seeds can be stored using standard methods, but many other seeds require special storage techniques. These techniques are improving quickly, but some areas may lack the tools or facilities needed to use them.

Some seeds cannot survive long-term storage and must be regrown by planting them to create new seeds. A study by Parzies and others in 2000 found that this process can reduce the number of plants and cause some genetic traits to be lost. This discovery has led seed banks worldwide to recognize that regrowing seeds does not perfectly preserve genetic diversity.

Alternatives

In-situ conservation of seed-producing plants is a method used to protect these species. This method includes creating National Parks, National Forests, and National Wildlife Refuges to preserve the natural homes of these plants. This approach allows plants to continue growing and changing naturally over time. In-situ conservation of agricultural plants happens on farms.

An arboretum is a place where trees are planted in a safe location to be protected.

A community-run seed library is a less costly way to save local plant genetic material.

It is well known that some seeds can stay inactive in the soil for long periods of time (Hills and Morris 1992). However, detailed information about the role of these "soil seed banks" in northern Ontario is very limited. More research is needed to learn about the types and numbers of seeds in the soil across different forest types, as well as the role of the seed bank in helping plants regrow after disturbances. Tables comparing seed numbers and variety are shown for boreal and deciduous forests, and the research done so far is described. This review includes information about: (1) how seed banks change over time, (2) how seeds function in a seed bank, (3) seed banks in boreal and deciduous forests, (4) how seed banks affect plant regrowth, and (5) suggestions for starting a seed bank study in northern Ontario.

Longevity

Seeds can remain able to grow for hundreds or even thousands of years. The oldest seed that has been tested using carbon-14 dating and successfully grown into a plant was a Judean date palm seed about 2,000 years old. It was found during excavations at the palace of Herod the Great in Israel.

In February 2012, Russian scientists reported that they successfully grew a narrow leaf campion (Silene stenophylla) from a seed that was 32,000 years old. The seed was discovered in a burrow 124 feet (38 m) deep in Siberian permafrost, along with 800,000 other seeds. Scientists grew the seed tissue in test tubes until it was strong enough to be planted in soil. This shows that DNA can remain intact and functional for a very long time under the right conditions.

Climate change

As climate change continues, efforts to protect plants, such as seed banks, are becoming more important. Seed banks help communities by providing seeds that can survive changing weather conditions. When climate change creates challenges, seed banks run by local people can give access to a variety of crops that are well-suited to the local area. These banks also support traditional knowledge about managing plants, including how to choose, care for, store, and share seeds.

Facilities

There are about 6 million seed samples stored in around 1,300 genebanks worldwide as of 2006. This number is a small part of the world’s total plant diversity, and many areas have not been fully studied.

• The Svalbard Global Seed Vault is built inside a sandstone mountain on the frozen island of Spitsbergen, part of the Svalbard archipelago, about 1,307 kilometers (812 miles) from the North Pole. It is designed to survive major disasters, such as nuclear war or world war. The vault is managed by the Global Crop Diversity Trust. The area’s permafrost helps keep the vault below freezing, and the seeds are protected by thick steel-reinforced concrete walls. The vault has two airlocks and two blast-proof doors. It received its first seeds on February 26, 2008.

• The Millennium Seed Bank is located at Wakehurst Place in West Sussex, near London, UK. It was started in 1996 and is the largest seed bank in the world. It plans to store seeds for at least 100 times more species than the Svalbard Global Seed Vault. The bank already holds over 2.4 billion seeds from more than 39,000 species. It also sends seeds to other important locations, tests each species every 10 years, and conducts other research.

• The Institute of Plant Genetic Resource in Saint Petersburg, Russia, is one of the oldest and still among the largest seed banks in the world. It was started in 1924 by Nikolai Vavilov, a Russian scientist. It survived the 28-month Siege of Leningrad during World War II because some botanists refused to eat the stored seeds and potatoes. Some sources say Alexander Batalin founded the seed bank in 1894.

• The Australian PlantBank is located in the Australian Botanic Gardens in Mount Annan, New South Wales. It is part of the Millennium Seed Bank Project and includes the former NSW Seedbank, which began in 1986 to preserve native Australian plants, especially those at risk. The Australian Grains Genebank (AGG), in Horsham, Victoria, stores genetic material for plant breeding and research. It works with the Australian Seed Bank Partnership on a project to collect seeds from wild relatives of crops. The AGG opened in March 2014. It was created because of the area’s extreme summer temperatures, up to 40°C (104°F), to ensure seeds remain safe year-round. The AGG aims to collect seeds from Australian wild plant species not well represented in other collections. The George Hulbert Seed Vault in Wagga Wagga, New South Wales, preserves rice varieties, including some from before the Green Revolution.

• The Indian Seed Vault is a secure seed bank in a high-altitude mountain pass on Chang La in Ladakh, India. It was built in 2010 and is said to be the second largest in the world. 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 seed varieties.

• The National Center for Genetic Resources Preservation in Fort Collins, Colorado, is the largest seed bank in the United States. The Desert Legume Program (DELEP) in Tucson, Arizona, focuses on legumes (plants in the Fabaceae family) from dry regions worldwide. DELEP has over 3,600 seed collections from nearly 1,400 species in 65 countries. These seeds are also stored in the National Center for Genetic Resources Preservation and the Svalbard Global Seed Vault. DELEP is part of the North American Plant Conservation Consortium.

• The National Gene Bank of Plants of Ukraine was created in the 1990s. It is described as one of the largest seed banks in the world but was damaged during the Russian invasion of Ukraine in 2022.

• The INRAE Centre for Vegetable Germplasm in Avignon, France, stores over 10,000 species of five vegetable crops as seeds: eggplant, pepper, tomato, melon, and lettuce, along with their wild or cultivated relatives. These species come from diverse geographic areas and are well described with data about their traits.

• Meise Botanical Garden in Belgium houses a seed bank that preserves endangered and rare wild plants from Belgium. It also stores wild beans, wild bananas, and seeds from Copper plants of Katanga.

Seed banks classification

Seed banks can be divided into three main types: community-focused, agriculture-focused, or conservation-focused. In practice, many seed banks use a mix of these types, and their priorities depend on their goals and the needs of the area they serve.

• Community-focused seed banks: These seed banks mainly help local communities and small farmers. They provide seeds that grow well in local conditions and are easy to grow and care for. They focus on seeds that produce a lot of food, resist pests and diseases, and need little help to grow.

• Agriculture-focused seed banks: These seed banks mainly support large farms and commercial agriculture. They provide seeds that produce a lot of food, resist pests and diseases, and need little help to grow. They focus on seeds that work well with large farms using machines and can be grown in large amounts.

• Conservation-focused seed banks: These seed banks mainly aim to protect the variety of genes in wild and farmed plants. They work to save seeds from plants that are rare, at risk of disappearing, or have special traits. They make these seeds available for research and breeding programs.

Early concepts

In Zoroastrian mythology, Ahura Mazda told Yima, a famous king from ancient Persia, to build an underground place called a Vara. This structure was meant to hold two seeds from every type of plant known at the time. The seeds had to come from plants without any problems, and the Vara had to be strong enough to survive a 300-year winter that would bring great destruction. Some experts believe a similar story exists in Norse mythology, where an underground garden called Odainsaker was created to survive a three-year long winter before Ragnarok. This garden was meant to protect people and plants that would help the world grow again after this event.