Basic Points in Seed Storage
- Seeds require a cool and dry location in which to be best stored. Temperature and humidity fluctuations are seeds’ worst enemies.
- The most vigorous seeds at harvest time will keep the longest in storage. (As a principal we only sell the brands that have the most vigorous seeds.)
- Improperly dried seeds can deteriorate drastically over time. (The seeds we sell have been dried properly before they are packaged and you only need to store them in a cool, low moisture environment for optimum preservation).
- Bags and jars should be clearly labelled at time of storage with strain name, date and other relevant information about the strain you are preserving.
Seeds carry on life processes, at a low rate, whilst dormant. Moisture they absorb from the air combines with stored nourishment within the seed to form a soluble food, which then combines with oxygen from the air to release water and heat. Too much moisture in the air will cause the seed to burn up its stored food too quickly producing excess heat which will further lower the seeds ability to germinate. The need is to keep these exchanges to a minimum during storage to prolong life in the seed.
6-9% moisture is ideal for long term storage of hemp seeds. A test for moisture levels shows that hard shelled seeds like hemp seeds shatter instead of mashing at around 8% moisture when placed on concrete and struck with a hammer.
Silica gel, often used in the drying of seeds, can also be used to help maintain stable moisture levels within a permanent storage container. Equal weights of silica gel to seed are used. In general hemp seeds weigh between 0.01 and 0.02 grams and our silica gel sachets contain 0.5g. We recommend seeds are kept in aluminium zip-lock bags and stored inside seed jars along with the correct amount of silica gel to maintain low moisture levels. Be aware that you can seriously damage seeds by reducing moisture levels too much, so do not use too much dessicant.
Seeds can survive temperatures that would kill the parent plant as long as they are thoroughly dried. Excess moisture in seeds that are then frozen can potentially freeze, damaging the seed.
Seeds need to be stored in a cool or cold place. Therefore, locations at floor level are preferable to those nearer the ceiling which can be significantly warmer. However, for long term storage, placing seeds in the fridge or freezer is ones best bet, as long as moisture content of the seed and storage container is low and the container is air-tight. The ideal temperature in a refrigerator is around 4oC.
A freezer is best for long-term storage of seeds although you need to make sure:
- You do not take the seeds out too much or for long enough for the temperature change to affect the seeds.
- When you want to remove seeds from the freezer, you leave the container closed whilst the seeds warm to room temperature or otherwise condensation will form on the seeds.
Similar to moisture and temperature, light can help stimulate and support the germination process. And, just as many foods, pharmaceuticals and chemicals rapidly deteriorate when exposed to light, so also is seed viability and vigour affected by being exposed to light during storage.
Seed Storage Problems
Seeds which have not been dried to the correct moisture content before being sealed in containers, can and frequently do rot. A simple test: after «drying» and placing in closed glass jars, the appearance of condensation on the inside of the jar within a few hours indicates the need for further drying. Silica gel should help with this.
Insects that may have escaped notice can wreak havoc on stored seeds. A few pinches of diatomaceous earth (DE) is a safe, inexpensive and non-toxic way of protecting seeds against insect damage. It doesn’t take much; just be sure to lightly coat all seeds before final sealing and storage. DE is available at most garden centres.
Seeds which are not stored in glass or metal can provide a veritable banquet for mice and other small vermin. Make sure all seeds are kept in well labeled metal or glass containers.