Collecting a Retention Sample
A retention sample is a representative sample of a lot, batch, or shipment of a herb that is retained by the supplier when the lot, batch, or shipment is sold up the supply chain. Should questions arise at a future date regarding the identity or quality of the material shipped, the seller and buyer can use the retention sample to resolve questions about the material. Maintaining a retention sample for properly identified material provides an important back-up resource for suppliers when dealing with questions from buyers. Suppliers with properly catalogued retention samples (with the same identification number as the lot/batch/ shipment from which it has been retained) will be able to quickly address any suggestions that the ‘wrong’ material was supplied.

A retention sample must be representative of the material shipped if it is to provide an accurate snapshot of the shipment. Samples must be taken only after the lot or batch has been made up or mixed together. If it is removed prior to mixing, there is the risk that only a portion of the shipment will be sampled – for example, the material provided by an individual wildcrafter – which may not provide a good representation of the larger shipment. Once the material is combined and ready to be shipped, a small portion (at least a handful) should be removed from the shipment. If multiple bags are being shipped, it is recommended that a small portion is extracted from each bag and then mixed together as the sample.

Retention samples should be stored away from heat and direct sunlight and protected from insects. Samples should be retained for a period of at least three years.

Storing Seed Samples

As with the retention sample and the voucher specimen, keeping a representative sample of the seed you use for sowing your crop will assist in answering any questions about crop identity that may arise pre- or post harvest. Provided the sample is stored properly, seed will remain viable for a number of years and can therefore be grown out to confirm the identity of the plant should some discrepancies between the identity of the seed and the resulting crop occur.

Storage temperature, relative humidity, and seed moisture are all important factors in determining how long seed can be stored without a significant decline in viability. The storage life of seed also varies greatly between species.

In general, longer seed life in storage is obtained when seeds are kept dry and at low temperatures. Dry seed should be placed in packages and stored in moisture-proof containers. Containers such as sealed cans or jars with air-tight caps work satisfactorily. Storage temperatures between 1°C and 10°C are satisfactory when the moisture content of the seed is low, especially if seeds only need to be maintained in a viable condition for 3-5 years. If space is available in your freezer, the seeds of many species can be stored for extremely long periods at freezing temperatures.

How much seed should you save?
The simple answer is ‘enough to ensure a sample of viable seed can be maintained for that specific seed source and crop’. Seed size varies tremendously between species. More than the bulk of the seed, it may be more appropriate to consider how much seed (under proper storage after three years) would be required to successfully grow a small plot of the species in question.