Hello Manfred I know a nursery tree grower (and botanist) who grows native Alberta trees and shrubs who has always kept his seed collection in a freezer year-round, which makes sense for species growing in this climate. He also stored all kinds of grass and wild-flower seed, as well as vegetable seed. Some were in paper bags, brown envelopes, small jars, whatever, and grouped together loosely in small cardboard boxes or plastic bags. They stayed viable for many years, and I remember some primrose seed still germinating well after 15 years. So I learned from his success and now do the same.
One of the best ways I have found to organize collected seeds is to put them in 6" x 9" envelopes, (the type with the flap on the short side), then store them upright in a shoe-box or small carton. The seeds will not fall out if the flap is at the top and folded down 1/4". If you then write the ID and date etc. on the front of the envelope just a bit down from the top edge, you will be able to see exactly what you have, even alphabetically if inclined. I also store these boxes in a deep freezer inside a plastic bag. Tomato seeds keep very well this way, and one variety (Gardener's Delight) I was given in England in 1993 still germinated last year. I have heard that some tropical seed species would not like to be frozen. Eve
