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Seed Collecting
Seed Banking

In the Foundations of Seed Banking course, you mention that seed banking can start small and build up incrementally, but the course is pretty technical and focused on a larger seed bank. Why is that?  

We absolutely encourage people to start small with seed banking if they have limited resources. Even with a small space, low-tech equipment, and a little background knowledge, seed banking can be a wonderful tool to store seeds for the future. Every bit of work done to preserve Earth’s precious resources can contribute to a better future for our planet!

However, while anyone is welcome to take our courses, our primary audience is people and organizations who are ready to begin seed banking at a larger scale — to support reforestation projects at a larger scale. As our CEO, Yishan Wong, says, “We believe that mass forest restoration is still the most practical and immediately scalable way for the entire world to reach net zero before it is too late.” This urgency is why our training courses are aimed at larger-scale conservation and restoration techniques to address this global need for rapidly scaling up our efforts.

Why isn’t seed dormancy covered in TFA’s seed banking course? 

We plan to cover dormancy in our Advanced Seed Banking course, currently in the development stage. Seed dormancy is complex, and reviewing the major categories of dormancy will require its own lesson. We also want to give as much practical, applicable knowledge as possible, but there are hundreds of potential techniques or treatments for overcoming seed dormancy, many which may be unique to certain regions.

We will cover some of the major categories of techniques, such as scarification, after-ripening, temperature stratification, water treatments, and chemical treatments. However, we also hope to engage with experts around the world who can share ideas and even educational content, building up a global library of practices to help solve problems in seed banking and forestry – including seed dormancy challenges.

We recommend the book Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination, by Carol Baskin and Jerry Baskin, as the most comprehensive resource on seed dormancy types in species around the world (which may also be available at a library, university, or botanical garden near you). You can also contact us if you have any specific questions on seed dormancy.

What if I need help troubleshooting problems with collections that come into my seed bank?

We plan to cover troubleshooting incoming collections in our Advanced Seed Banking course, currently in the development stage. This will include topics such as how to handle insect pests, fungal growth, poisonous plants, overripe fruits, and immature fruits. We aim to give practical advice on how to minimize the damage that can be caused by these various problems, to help you maximize the quality of seed bank accessions, even when field collection presents challenges.

However, we also hope to engage with experts around the world who can share ideas and even educational content, building up a global library of practices to help solve problems in seed banking and forestry – including troubleshooting unique seed collection challenges in different parts of the world. In the meantime, feel free to contact us if you have any specific questions on troubleshooting.

What if I cannot find any information on seed storage behavior of the species I work with? 

If you have already checked the Kew Seed Information Database and searched for any existing literature on seeds of your species, you have a couple more options. The Kew Millennium Seed Bank (MSB) has developed a Storage Behavior Prediction Tool, in which you can upload a list of species and the tool will predict the likely seed storage behavior of the species, based on MSB research.

Another option is to test seeds of a new species yourself, using MSB’s 100 Seed Test protocol for identifying desiccation-sensitive seeds. We also plan to demonstrate how to use and adapt this protocol in our Advanced Seed Banking course, currently in the development stage.

What are some different options for drying my seeds? 

Drying racks are provided in Terraformation seed banks, and this is also something you could easily set up yourself. Any kind of rack system or shelving that allows for shallow trays with good airflow could be used for this purpose. To use the racks, simply spread the seeds out in a single layer in one or more trays, with only one seed accession per tray. It is critical that seeds are in a single layer, so that all the seeds dry evenly. Otherwise, seeds underneath other seeds will retain more moisture. For a Terraformation seed bank kept at 35%–40% (RH), these racks can be used to dry seeds for frozen storage.

Electronic drying cabinets (which may also be called dry cabinets, electronic humidity control chambers, desiccation chambers, or similar names) allow a user to control the internal relative humidity. Terraformation seed banks are equipped with four drying cabinets. These are relatively inexpensive and sufficient for restoration seed banking. We recommend setting three cabinets to 30% RH and the last one to 40% RH. You can use the cabinets at 30% to dry seeds for refrigerated storage at 5°C, and the cabinet at 40% to dry small seeds for frozen storage at –20°C. Of course, you can also adjust the cabinets for your seed bank’s needs. As with the drying racks, spread the seeds out in a tray appropriate to the size of the seed accession.

One other useful option for seeds that will be refrigerated is to dry them on drying racks for a while, then move them to the drying cabinets to reach 30% RH.

Other Options

In addition to drying tools provided in Terraformation seed banks, there are also a variety of non-electronic dry boxes, often made of clear acrylic material for viewing internal contents, with hermetically sealing doors. This can work quite well as a low-tech option with no power required for the drying unit itself. However, these dry boxes will require some type of desiccant inside in order to dry the seeds, and the desiccant will also need to be recharged, which will require some use of power.

Some dry boxes have corresponding silica gel desiccant cartridges, in which case, it is good to have several of these cartridges on hand, because it is likely that seed drying will require frequent cycling/recharging. You would also need to have an oven available to recharge the cartridges using low heat.

As a cheaper alternative, you may be able to purchase silica gel beads in bulk (not in a cartridge) and simply place them in a tray inside the dry box to do the desiccation work. They will still need to be regularly recharged by spreading them out on a tray in an oven on low heat.

Important note on silica gel: Color indicating silica gel beads are important, so that you can visually tell when the silica gel has become saturated with moisture and is no longer able to dry the air and the seeds inside the box. However, we recommend not to use blue-to-pink color indicator beads, because these contain a chemical that is a carcinogen if the beads are broken into particles that can be inhaled. Blue-to-pink beads can be ok contained inside a cartridge, since this would avoid breakage, but we don't recommend using them in the open, especially if they are handled over and over again in recharging. Instead, orange-to-green color indicating silica gel beads are a safe alternative. They are recharged in the same way but do not contain hazardous chemicals. Since color indicating silica gel is more expensive than regular white silica gel, one option is to buy both types, mixing in some color-indicating with the regular white silica gel (they should all need to be recharged around the same time).

Finally, in some places in the world, you can purchase mini-dehumidifier units that contain silica gel inside and can be recharged simply by plugging the unit into a standard electrical outlet. These are convenient, and a seed bank could purchase enough of them to keep recharging and cycling through their non-electronic dry boxes. With a larger box full of fresh seeds, they may need to be recharged every week or few days. However, drying seeds on drying racks first, then moving partially-dried seeds to cabinets would reduce the frequency of recharging any of the options above (essentially using dry boxes for fine-tuning and for collections of very small seeds).

Does my seed bank need a fume hood? 

The purpose of a fume hood in a Terraformation seed bank is to protect the seed bankers from any hazardous particulates inside the small space of the container. The main reasons to have one are if (1) any of the species you work with have poisonous plant parts, especially fruits and seeds, (2) any of the species you work with may create a lot of dust during processing, or (3) you expect to deal with a lot of mold. The best practice is to avoid collecting any seeds with mold, but some species and locations are more susceptible.

If your seed bank needs to purchase a fume hood for health and safety reasons, keep in mind that they usually have a long lead time for shipping. We also recommend that you contact the fume hood supplier directly and ensure you are purchasing the correct model and filters that will protect the user from particulates - rather than creating a sterile environment for the specimens inside (the latter is not necessary for seed banks).

Another option is to create an external but sheltered processing area on the outside of your seed bank, where you can process seeds without exposure to sun and rain, but with good airflow for any particulates that might be irritants. For poisonous plants or any more severe hazards, make sure all workers wear a mask that will protect them, to the degree necessary for your work.

How do I choose a refrigerator for storing my seeds? 

The reason many standard kitchen refrigerator/freezers work for restoration seed banking is because if they are single-evaporator models, the freezer self-defrost cycle lowers the humidity inside the refrigerator compartment. Stand-alone refrigerators (or dual-evaporator refrigerator/freezers) maintain higher humidity in the refrigerator - good for produce, but bad for seed banking. If you wanted only refrigerated storage, you would need laboratory-grade or industrial refrigerator units. Kitchen refrigerator-freezers must be single-evaporator models. Target temperature inside the refrigerator is 5°C and inside the freezer is -20°C, which is in the standard range of most kitchen units.

Ideal specifications for refrigerator-freezers inside a Terraformation seed bank include:
  • Reliable brand, self-defrosting with single evaporator (critical for humidity control)
  • Upright, either top/bottom or side-by-side is ok (without a water/ice dispenser)
  • Approximately 500-600 L capacity (18-22 cubic feet)
  • Maximum dimensions: 2200 mm (90 inches) height x 800 mm (30 inches) width x 800 mm (30 inches) depth (including the door)


With three refrigerator/freezer units of this size in your seed bank, and when banking seeds of a diverse set of species (where you have a mix of large and small seeds), you can bank at least 3 million seeds at any given time.

How long could a seed bank be without power before damaging the seeds? 

This question is so tricky, and there is not one universal answer. Relating to Harrington's Rule, anytime stored seeds are exposed to higher temperatures, they will begin aging faster. When the temperature goes back down, they will return to aging very slowly. So if the power is down for only a couple hours – and the freezers, refrigerators, and seed bank doors are all kept closed to keep the temperature lower inside – the damage may be minimal for most species.

If a restoration seed bank’s power is down for many hours or days, the damage may be minimal for some species and severe for other species. Because of the seed survival curve (sigmoid curve = a gradual decline followed by a steep drop in viability) and the fact that a seed bank contains seeds stored for different amounts of time, certain seed accessions may be exposed to that steep drop by a power outage that speeds aging. Therefore, this consideration is not just species-specific, but accession-specific too.

In any power outage, make sure to keep doors closed on refrigerators, freezers, and the seed bank itself to keep the temperature and relative humidity as close to their targets as possible. Aside from restoring power quickly, this is the best thing you can do to minimize damage to your seeds.

If you work with species where research has given us some idea of how long the seeds will survive in storage, we might be able to advise you on what length of power outage means you need to prioritize testing/using the stored seeds (especially older accessions). But more importantly, we need to make power outages very short and very rare events! This is why a backup generator is an essential piece of equipment for all seed banks, and an automatic-start backup generator is ideal.

Does my backup generator really need to have an automatic start? 

Having a manual-start generator as backup can be workable, but it can be very stressful if power outages do occur in your area. If there is always a caretaker on site, this would be one situation where a manual-start generator is not a problem.

However, if you do not have a caretaker on site 100% of the time and must use a manual-start generator, then you should have remote monitoring for power outages, with sensors that notify at least two people by SMS text if power is out for more than a very brief period (in many places, 5 minutes without power is a good alert threshold, so that you aren't alerted for very brief, self-correcting outages, but you can begin addressing the issue quickly if the outage continues). You also need an emergency response chain in place. For example, an on-site caretaker is a good first responder, since they are often nearby. In case that person is not available, have at least two more people, trained in generator operation, who can be ready to respond. The person living closest to the seed bank is a logical choice for second in the response chain.

One additional challenge with power outages could be if they are caused by a situation that also blocks access to the seed bank, such as a downed tree that takes out a power line and also blocks the road to the seed bank. It is good to keep in mind what conditions cause power outages near you when deciding on a backup generator.

If you do use a manual-start generator, remote alerts are critical, and the emergency response chain needs to be clearly defined. If you can make sure the generator is turned on within a couple hours of any power outage (and refrigerators, freezers, and the seed bank door are kept closed during that time), and outages are not too frequent, then a manual-start generator may work for you. However, automatic-start generators are recommended in most cases, to protect seeds and give seed bankers peace of mind.

How do I deal with static that makes small seeds difficult to manage? 

Some seeds are vulnerable to static, especially lighter seeds (such as those under 1mg) and seeds with a pappus (the fluffy appendage on many seeds in Asteraceae, the sunflower family, which allows them to float in air currents). In general, many wind-dispersed seeds would also be prone to static issues.

Static doesn't usually damage seeds, but it can make seeds very difficult to work with. It can be especially challenging to clean them and separate them from light debris that also gets a static charge. Although occasionally, you can use static to your advantage if light debris sticks to a surface while seeds do not. Static can also make seeds "jumpy" or stick to the wrong places unintentionally, sometimes getting lost more easily. It can be very annoying! And it happens even in parts of the world where static isn't usually common, like humid tropical locations, because the inside of the seed bank is relatively dry.


There are a couple things you can do to minimize static issues:
  • Avoid using plastic or acrylic trays for dry seed processing, as these materials are more prone to static. Using metal or cardboard trays can help reduce static.
  • Use an anti-static brush to wipe down surfaces such as trays and workbenches to decrease the likelihood of a static charge building up. After you finish processing an accession, disinfect the working surface, allow it to fully dry, and wipe down the surface with an anti-static brush again just before working with more static-prone seeds. Avoid using anti-static brushes directly on seeds, because they can get stuck in the bristles.

Why is it problematic to use common names of plants in collection data? What if I don’t know the scientific names of some species?

Common names are challenging for many reasons. Often the same common name is given to multiple unrelated species, even within one region, or one species has many different common names, or the local common name is different from a more widespread common name. Additionally, common names are often very botanically misleading, indicating plant families that are very distantly related, such as flowering plants given a “fern” name, many non-grass plants given a “grass” name, and many non-lily plants given a “lily” name, just to mention a few.

If you don’t know the scientific names for some of your species, there are databases that can be a good starting point to determine them. Some excellent global databases of plant names include Plants of the World Online, International Plant Names Index, and World Flora Online. Many regions and countries have also developed botanical descriptions of native plants, or other guides to local floras (online and/or as published books). The Biodiversity Heritage Library provides scanned copies of books for some regional floras. Other great resources might include any botanical gardens, herbaria, or universities in your region, which may have experts in plant systematics and taxonomy who can help you identify species with scientific names.

I did a cut test on some seeds to check for viability, and they look very different from the textbook diagram — why is that? 

This is not unusual at all! There is incredible diversity of forms and appearance among seeds — on the inside as well as the outside. The diagram in our textbook is generalized to show how some wild-collected seeds might look inside, but the actual seed anatomy of different wild species varies just as much as other plant characteristics do.

Our diagram shows a seed with a moderately thick seed coat, an embryo that is easily visible but takes up less than half the space inside, and food storage in the form of endosperm that takes up more than half the space inside. Here are some ways your seeds may differ:

Seed coats can range from paper-thin ones that remove easily, to ones that are hard, water-impermeable, and several millimeters thick — and everything in between. Their texture can also be anything from completely smooth to highly textured (appearing furrowed, wrinkled, bumpy, etc). They may also have tufts of hair or fluff, sharp prickles, wings, or other appendages, which are usually either related to how the seeds are dispersed or may be a deterrent to animal predators that could eat the seeds. They can also be almost any color or shape imaginable!

Embryos can range from being very tiny, underdeveloped, and difficult to see, to taking up much of the space inside the seed as an almost fully developed seedling. When they are tiny, it might even be difficult to find the embryo inside the seed, but if the endosperm tissue looks healthy and hydrated (and the seed looks fully formed), that often indicates that the seed is viable.

Food storage can take the form of endosperm or cotyledons.
  • Endosperm is a starchy tissue derived from the mother plant which serves as a food source for the embryo while inside the seed. It should usually appear whitish in color, well hydrated, and be filling up whatever portion of the seed is not taken by the embryo.
  • Cotyledons are embryonic leaves present within the seed that will serve as a food source for the newly germinated seedling. They are the first leaves you see on a germinated seedling, before it starts making true leaves (which develop only after germination has occurred) to create its own food through photosynthesis.
  • The embryo consumes the endosperm and develops cotyledons while still inside the seed. Depending on the species, an embryo could be much earlier or much later in that process when the seed becomes mature or ripe. If a seed is mature when the embryo is still under-developed, then it has dormancy — an inactive state that delays the germination of a seed.
  • There are exceptions, such as orchid seeds, which only have an embryo and a seed coat, with no food storage inside the seed. This is why orchid seeds require specific symbiotic fungi (mycorrhizae) to provide a food source for germinating seedlings.
Sometimes seeds are even found inside an endocarp, which is another shell-like layer between the seed and the fruit. The endocarp might be thin and easily removed. However, if the endocarp is hard or stony, it might be difficult to cut and remove seeds from inside. In this case, some people propagate or store the whole endocarp. However, be aware that sometimes one endocarp can contain multiple seeds.

If I work with a species that has recalcitrant seeds and cannot be stored in a seed bank, are there any other options besides propagating all seeds right after they are collected?

Yes! There are other options for recalcitrant seeds. However, they do require some specialized knowledge and techniques. Here are a few of the possibilities:

Sometimes, it may be possible to store recalcitrant seeds for a short period of time. This might mean keeping the seeds inside the fruits, so they do not dry out, and storing them in a protected/shaded location in humid conditions. However, it may not work for some species, or might only work for a few days. If you have abundant seeds, you could test this by trial and error, but we recommend checking for any local resources or expertise first. There may be botanical gardens, universities, or other restoration projects in your country or region where people have experience with your species. The Seed Conservation Directory of Expertise is another place to search for experts in your region.
For common native species that have recalcitrant seeds, an alternative to seed banking is seed production areas (SPAs). They can also be used together with seed banking for species with orthodox seeds that are difficult to collect in the wild. In the context of ecological restoration, SPAs are managed plantings of wild-sourced plants for the specific purpose of increasing the number of seeds available for restoration. They can range from small seed beds managed by one organization to large networks of SPAs under government or commercial management. SPAs can focus on one species or contain a mixture of species. If you face challenges with seed sourcing or seed banking, establishing an SPA (or connecting to an existing SPA network) might be a useful option. However, it is important to distinguish an SPA for restoration from SPAs for agricultural or other commercial purposes, which may focus on traits such as minimizing dormancy (speeding germination) or synchronizing germination (so that seeds germinate at the same time). While these traits make it easier to grow plants, this eliminates a lot of natural genetic diversity found in wild plants, which ultimately causes the plants to be poorly adapted to natural conditions in restoration sites. In addition, even restoration-focused SPAs face risks to genetic diversity resulting from cultivation, so it is critical to plan and manage SPAs carefully. To learn more, we recommend the articles “Seed production areas for the global restoration challenge” (Nevill et al. 2016) and “Seed production areas are crucial to conservation outcomes: benefits and risks of an emerging restoration tool” (Zinnen et al. 2021).

For rare, endangered, and endemic species conservation, there are high-tech options such as cryopreservation and micropropagation. Cryopreservation uses liquid nitrogen to quickly freeze seeds (or embryos, other tissue samples of plants, or even animal cells or tissues) to extremely low temperatures, usually below -140°C. There is promising research that shows cryopreservation can be an effective method for storing some recalcitrant seeds or embryos, but it requires specialized equipment and knowledge. Micropropagation uses a sterile environment to grow plants in vitro — under glass, such as in test tubes — and can include tissue culture, where plants are grown from seeds, embryos, or even other plant tissue. It works well for many species, but it requires a specialized laboratory, and growing protocols often need to be fine-tuned for each individual species. Both methods have some limitations and will not work for all species with recalcitrant seeds. The Center for Plant Conservation is a great place to learn more about these methods.

Can I use seed production areas (farming native seeds) if seeds are difficult to collect in the wild? 

Seed production areas (SPAs) can be a useful alternative to seed banking for species with recalcitrant seeds. They can also be a valuable tool to use along with seed banking, if you work with species that have orthodox seeds but are difficult to collect in the wild. This might be due to biological reasons, such as a species that doesn’t produce seeds every year, or logistical reasons, such as a species that only occurs in areas that are very difficult to access. However, if enough seeds can be collected, you may be able to establish an SPA.

In the context of ecological restoration, SPAs are managed plantings of wild-sourced plants for the specific purpose of increasing the number of seeds available for restoration. They can range from small seed beds managed by one organization to large networks of SPAs under government or commercial management. SPAs can focus on one species or contain a mixture of species. If you face challenges with seed sourcing or seed banking, establishing an SPA (or connecting to an existing SPA network) might be a useful option. However, it is important to distinguish an SPA for restoration from SPAs for agricultural or other commercial purposes, which may focus on traits such as minimizing dormancy (speeding germination) or synchronizing germination (so that seeds germinate at the same time). While these traits make it easier to grow plants, it eliminates a lot of natural genetic diversity found in wild plants, which ultimately causes the plants to be poorly adapted to natural conditions in restoration sites. In addition, even restoration-focused SPAs face risks to genetic diversity resulting from cultivation, so it is critical to plan and manage SPAs carefully. To learn more, we recommend the articles “Seed production areas for the global restoration challenge” (Nevill et al. 2016) and “Seed production areas are crucial to conservation outcomes: benefits and risks of an emerging restoration tool” (Zinnen et al. 2021).

How do I use seed zones to make decisions about sourcing seeds? 

A seed zone is an area within which seeds can be collected, and the resulting plants can be planted, with a low risk of the plants being poorly adapted to the new location. Generally, it is better to source seeds as close to the intended planting location as possible, but this can often be challenging. Sometimes seeds can be sourced from farther away, if the source location is environmentally similar to the planting location.

Seed zones can be developed in two ways:
  • Empirical seed zones are developed for a particular species based on research with genetic data. If it is well understood how genetic variation is distributed among populations of a plant species, then seed zones can be created in detail. These can be used and followed with a high degree of confidence, but they only exist for relatively few species.
  • Generalized provisional seed zones are developed when genetic data is not available, and consider major factors including geographic distance and environmental conditions such as topography, elevation, temperature, moisture, and light. They can be applied to any species; however, it is always best to apply as much knowledge as possible about a species’ biology when making decisions based on provisional seed zones. They are excellent to use as general guidelines, or as a place to start in making your seed-sourcing decisions, but they are not definitive rules. It may be possible that a good seed source for your particular species lies in an adjacent seed zone with an environmentally similar area. There may be botanical gardens, universities, or other restoration projects in your country or region where people have experience with your species. The Seed Conservation Directory of Expertise is another place to search for experts in your region. We recommend consulting with other experts if you can, and then making your best judgment based on experience.

What if no seed zones exist for my area? 

Seed zones have been developed for East Africa, parts of Europe, the contiguous United States, and Hawaiʻi, and they are in development in Australia. (If you know of seed zones developed in other areas, please let us know!) There are still many areas of the world where no seed zones exist. However, there are many resources for environmental data you can use to inform your decisions.

If you use Geographic Information Systems (GIS), you can download global climate data from the WorldClim database for mapping and spatial modeling. With the FAO Data App, you can use a web browser to explore data on variables related to land, water, climate, forestry, and more; you can add these layers to the interactive map and zoom in to your region of the world. For a simpler place to start, the 18 World Climate Regions map (based on a combination of temperature and moisture regimes) could be a guide in choosing the nearest location that occurs within the same climate region as your planting area. Another powerful tool which can provide you with additional information on climate variables, biodiversity, and restoration is Earth Map. It is an innovative, free, and open-source tool developed by the Food and Agriculture Organization of the United Nations (FAO) in the framework of the FAO - Google partnership.

Additionally, there may be botanical gardens, universities, or other restoration projects in your country or region where people have experience with your species. The Seed Conservation Directory of Expertise is another place to search for experts in your region. We recommend consulting with other experts if you can, and then making your best judgment based on experience.