How do I collect and store seeds from my garden?
Taking care during the collection of seed can make a huge difference to its storability.
Bank your own seeds
Store your garden seeds safely in a Mini Seed Bank. Available from Kew shops
Collecting before the seeds are fully ripe may mean that the seed is incapable of surviving drying. Where dry seed capsules are involved, the ideal harvest time is usually when the seeds are on the point of being shed e.g. when a seed capsule first splits. In the case of 'wet' fruits containing seeds, the ideal harvest time is when the fruits are fully ripe, and therefore attractive to mammals and birds. Quite often, fruit ripeness is indicated by a change of colour. Seeds that are very soft or that are green are usually not ripe. Where a range of seed colours is present on the plants, some indication of which seeds to harvest can usually be worked out by looking for those seed colours that equate to seed hardness.
Unlike most seed collecting for conservation that involves random sampling, gardeners may wish to be selective of the individuals to be harvested. This will increase (though not guarantee) the chances that some of the individuals in the next generation possess similar characteristics to those selected. Sexual reproduction results in a shuffling of the genetic variation present in the previous generation. Consequently, the greater the size of the next generation raised, the greater the chances of the desirable characteristics being found. Furthermore, F1 hybrid varieties will not breed true; these will need to be purchased afresh each season.
Sensible precautions should be adopted when handling all seed and fruits because some are poisonous. All such material should be kept out of the reach of small children. Seeds borne within fruits need to be extracted. This can be done by scraping the seeds onto a colander or sieve followed by washing to remove pulp and juice. Sometimes after extraction, the seed is covered with a mucilaginous layer. If the seeds are spread out and left to dry, this mucilage can usually be rubbed off. Similarly, obviously empty, damaged and poorly-developed seed plus debris is best removed from other seed collections prior to drying and storage.
Harvested seeds need to be dried if they are to be stored. Note that this will only be true for orthodox ( desiccation tolerant) species. Most garden plants grown in temperate regions will have such seed.
Drying seed shares many of the same principles as drying clothes. The one difference is that seeds (and particularly moist seeds) should never be exposed to high temperatures (and certainly not above 40°C) if they are to be kept for any length of time. Seed batches will dry most rapidly and furthest if spread out in a dry place where there is some air movement. If it is necessary to keep the seed in bags for drying, use non-glossy paper bags that allow moisture to pass out. Do not use plastic bags. An alternative drying method is to place the seeds for up to 2 months inside a relatively airtight box above a layer of fresh silica gel using a ratio of gel to seed of about 3:1. Carefully follow the supplier's directions when using silica gel. Alternative drying agents include oven-dried rice. An ideal way of drying seeds from the garden is to use the mini seed bank.
When the seeds have been dried they should be kept dry by being placed within an airtight container. Lever-lidded fruit preserving jars with rubber gaskets are usually excellent because they seal well and have a wide opening. Certain other types of readily available container may also be sufficiently airtight. Once dried, packaged and labelled, the seeds can be placed in a cool location. Domestic refrigerators are good though the seeds should be well separated from food and kept out of the reach of small children. When seeds are required, let the container warm up and dry off before opening. Then re-close as quickly as possible. It may be advisable to let the seeds pick up moisture from the air for several days prior to sowing, scarifying them first, if necessary.
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