Seed packing

Seeds of forest trees intended for the market must be enclosed in packaging that reveals whether the package has been opened before the next stage of production, i.e. either packaging into sales packages or using the seeds for their final purpose such as sowing in forests or nurseries. 

As a production stage, the packaging of forest tree seeds is supervised through inspections. Suppliers engaged in seed packaging must be entered in the forest reproductive material supplier register, maintained by Evira, as packagers of seeds.

A label denoting a forest reproductive material supplier, or another document containing detailed information on the origin and quality of seeds, must be attached to seed batches intended for the market.

Recommendations for seed packagers 1

Pine and spruce seeds retain their germination capacity well when their water content is 5–6 per cent and the seeds are kept at temperatures below +5˚C. Dry seeds easily absorb water and gradually attain a humidity level in balance with the relative humidity of the surrounding air. Humidity favourable to storage can only be attained when the seed is packaged in airtight containers after drying, or stored under conditions of 30–40 per cent relative air humidity. In normal indoor air, or in cold storage, the air humidity is usually considerably higher. In order to prevent seed from absorbing moisture during storage, packaging must be airtight.

Today, the most common packaging material is a polythene bottle that can be made airtight with a cap. Thin plastic bags and wrappers are easily damaged and too permeable to water and gases.

The less often storage containers are opened, the better the germination capacity of the seeds. We recommended that all seeds intended for storage be placed in sales packages immediately. When handling the containers, you must take account of the possibility that atmospheric water vapour will condense on the surface of cool seeds if the containers are opened before the temperature has evened out. For instance, it takes 36 hours for the temperature of a container with a capacity of 28 litres (containing 14kg of pine seed) to even out from -16 ˚C to +22˚C.

1Nygren, M. 2003. Forest tree seed guide. The Finnish Forest Research Institute (Metla). Suonenjoki Research Unit. Finnish Forest Research Institute bulletins 882:65—69.