Seeds from some types simply naturally remain feasible longer than other types. Some types of seed are so brief lived that they need to be sown and germinated in the same season that they are collected. Seeds from alpine locations typically have rather a short lifespan compared to those from lowland areas, many alpine types just make it through for a about a decade even when stored under perfect conditions in a reputable seed banks such as the Centuries Seed Bank at Kew Gardens in the UK.
The seed of some species, in specific lots of jungle plants, are what we term recalcitrant. Recalcitrant seeds are unable to make it through being dried out in the manner in which seed with a conventional dormancy can be. Recalcitrant seeds need to not be permitted to significantly dry between when they are planted and when they are germinated, this provides a challenge for storage as seed pathogens such as moulds grow in the moist conditions needed to keep recalcitrant seeds feasible for longer than about a week. Recalcitrant seeds are typically planted as soon as possible after harvesting. The veggie and flower seeds you buy in packages and plant in your garden at home on the other hand are examples of seeds with conventional inactivity and are rather happy to be dried out within limits.
Some seeds have a longevity that equals some of the earliest trees alive on the planet. The record for the longest seed worldwide to sprout comes from a 2,000 year old date palm seed. Extremely this seed wasn’t recovered from a place with perfect (steady cold and dry) storage conditions. Instead it was recuperated from a place near the Dead Sea which although very dry is also exceptionally hot with a typical optimum temperature level that varies in between 20 degrees Celsius in winter season to 39 degrees Celsius in summer season. The seed was germinated in 2006 and is still healthy and growing today. A 1,300-year-old lotus seed had also been previously germinated, however it didn’t handle the long storage period quite so well. The resulting plant was seriously malformed due to genetic irregularities.
So lets examine some of the aspects that can decrease seed viability in seeds with standard seed dormancy, that is seeds that can survive being dried and have about a 6-10% moisture content inside their walls once they are dried, and what can be done instead to maximise it.
Humidity & Seed Viability
The very first big factor affecting seed viability is wetness. It’s a well known reality that seeds live, they are a complete blueprint to create a brand-new plant encased in a plan that both protects it and provides energy to make it possible for germination. Due to the fact that seeds are alive they respire (although very, really slowly) just like any other living thing does and require oxygen just like any other living. However air is more than simply oxygen, air consists of moisture and a measure of this is known as relative humidity.
Too much moisture in the air will reduce seed viability and cause seed pathogens such as moulds to grow. However as seeds live they require some wetness to make it through, insufficient moisture in the air will dry the seed out excessive and eliminate the seed. In order to preserve the ideal moisture variety within the seed of 6-10% seeds should be kept in air that has a relative humidity in between 30 and 45%. In order to attain this, seed needs to be saved in a controlled (air-conditioned) environment set to within this perfect relative humidity variety. This solution, however, is rather costly and impractical except for large seed business.
As a cheaper alternative seed can be sealed into a airtight pouch or container when the external natural humidity is within this range, this will seal the seed in air that will stay within this ideal relative humidity range even as the external relative humidity changes. Any excess air in the pouch ought to be squeezed out or, if using containers, choose a container appropriate to the quantity of seed to be kept, remember seeds only require a minute amount of oxygen to preserve respiration.
Sealing the seed likewise prevents them from being eaten by insect pests, although little insect bugs will have no issue maintaining a growing neighborhood if they are present in the seed when it is sealed. It needs to likewise be born in mind that once opened, the relative humidity inside the container will equalise with the external relative humidity. It goes without saying that exposing the seed straight to water will set off germination, and any seed that is sprouted and dried again will die and no longer be feasible.
Temperature Level & Seed Practicality
The second big element impacting seed practicality is temperature level. As a general rule, the lower the temperature the seeds are saved at the longer they will remain practical; nevertheless, the stability of the temperature the seed are saved at is likewise crucial. Ideally seed needs to be saved in a controlled environment set to a low temperature level, or simply in a house that is maintained via air conditioning at a continuous temperature.
I do not have air conditioning, so I tend to store any seeds under my home where it’s typically a bit cooler during summer than inside your house. I use an old refrigerator to save the seed in; it is not switched on, however the insulation in the walls of the refrigerator assists to keep the temperature level more stable by decreasing some of the extremes in temperature level experienced in the middle of the day and night.
Some individuals like to keep seeds inside their grocery refrigerator but refrigerators can at some point be rather damp, so seed kept in this manner should be kept in an airtight container. Some refrigerators have a low-humidity crisper section, and this is the very best place to store seed if you are keeping your seed in this method. When getting rid of seed from a refrigerator, make sure sit the container out on the bench for some time to allow the temperature level inside the container to equalise with the outdoors temperature level before opening, otherwise condensation can happen, which will damp and destroy your seeds.
Should I Freeze Seeds?
No seed ought to ever be frozen unless they are first dried to a wetness level at the low end of their tolerable range as any excess moisture within the cells of the seed will form ice crystals, which can burst cell walls and trigger the death of the seed. Without the sophisticated equipment, some seed banks need to freeze their seed for long-term storage; drying the seed to the right level is extremely challenging and not usually achievable for home gardeners.