Could you provide more details on exactly what you are looking for? Are you looking for guidelines for commercial purchased or self-saved seeds?

Seed viability is a complex equation that includes many variables - age of seed, storage conditions, storage time, % of moisture content, temperature at harvest and during storage, etc. and requires germination testing as one of the variables. So it would be impossible to compose a list that would be applicable to any sort of broad base situations or to address many different varieties.

Some viability models have been done on some common varieties and theoretically you can do your own tests on particular batches of seeds (just as the commercial vendors do) IF you have data on all the variables in the formula.

Current best source of info is the models of some 70 seed varieties being done by the Millennium Seed Bank (kew.org) but FAIK not much of the specific results have been published yet.

Dave

Here is a link that might be useful: Millinnium Seed Bank

What Dave said....but also, is it possible you are looking for germination information on different types of seeds? If so, there's a very recent thread about that. I will link it below, just in case.

Here is a link that might be useful: Seed Germination Databases

Thanks, Dave and Brandon. I'm looking for general indications of seed viability over time (number of years, approximately), when stored under more or less ideal conditions. It's useful to know, e.g., that delphinium seed is not long-lived (the sources usually say 1 year), whereas nasturtiums are quite long-lived (six years, according to some).

Having built a neat outside greenhouse two springs ago, I've been growing more plants from seed, perennials especially, initially in the basement under controlled conditions, to be moved out to the heated GH around mid-March (still very cold in MN). In cases where the packet contains more seeds than I can use in one season, it's useful to know which can be stored and sown in a subsequent season.

I found the germination databases very helpful, but this is really a different issue. Appreciate your feedback.

Gary

I am not aware of a database like you are asking for. As Dave hinted at, such a database would have to cover so many variables that it would be highly complex (it would at least have to consider temperature, temperature variation, moisture, initial collection times, etc) or be practically useless. I can imagine someone doing a real-rough-idea generalized type of list like you are wanting, but I haven't seen one.

In cases where the packet contains more seeds than I can use in one season, it's useful to know which can be stored and sown in a subsequent season.

Easy answer - they can all be saved. Depending on the storage you will still get some germination - even from things like alliums and delphs.

Germination rates decline slowly. Freezer storage prolongs storage life even longer but great care needs to be taken when removing them from freezer storage.

Dave

Fedco has one for common vegetables.

Here is a link that might be useful: Fedco veggie seed viability

Some seeds can go bad within a week or so (really that fast) when stored in typical home conditions. Others can stay viable for tens of thousands of years (yes you read that right), when given the right conditions. The average orthodox (as opposed to recalcitrant) seeds probably retain a fair amount of their germination percentage for about two years when stored in typical home conditions. Putting them in the frig (not freezer), in a plastic bag to retain some moisture), can prolong that time period. If you keep a bowl of water nearby to keep moisture levels high, that would be even better.

Thanks for the additional information. Poking around for more details on relation between moisture and temperature in storing seed, I came upon this URL from Colorado State Extension service. Helped clarify some things for me.

Gary

Here is a link that might be useful: Storing Vegetable and Flower Seeds

The Colorado State article makes some generalizations that are not proper for some seeds. It seems to be addressing common vegetable-garden seeds, which it probably does sufficiently. One needs to consider whether seeds are orthodox, recalcitrant, or somewhere in between and possibly various dormancy issues. Drying (which the article recommends) recalcitrant seeds reduces their germination rate and, if done sufficiently, will kill the seed. The article seems to only address orthodox seeds, although it doesn't explain that. I'm not even sure the article describes the drying process for orthodox seeds sufficiently. Even they can be dried out too much.

I didn't read through the article, linked below, carefully, but it appears to cover the topic fairly well. I'd recommending reading it to get a better idea of seed storage issues and techniques.

Here is a link that might be useful: Seed Storage

If you're not sure about your seeds test them.

Ever year before I do my seed order I go through my existing seeds and test the ones I'm concerned about.

I take 10 (or fewer depending on how many I have) and put them in wet paper towel in a Ziploc bag to keep them from drying out. I place the bag in a warm place and check it every couple days to see if the seeds sprout.... and depending on how many sprout and how long it takes, I either keep the seeds or turf them.

My experience with sowing is mainly with woody species and to a lesser extent also with perennials.

Based upon my own experiences and scientific literature found on the Internet the following woody species have a short term viability and are best sown as soon as the seed is ripe (fresh seed). This does not mean that 'old' seeds of these species will not germinate but the germination rates may be very low. Especially if you are buying seeds this is something to take into consideration. Some of the species mentioned below can remain viable for a longer period of time if stored under very specific conditions but this is often impracticle or unattainable for the amateur gardener.

Woody species with seeds that have in general a short term viability (please note that this list is NOT exhaustive):

Acer platanoides
Acer saccharinum
Aesculus species
Alnus species
Araucaria araucana
Asimina triloba
Berberis species
Camellia species
Carya species
Castanea species
Daphne species (seed should be absolutely FRESH)
Euonymus species
Fagus species
Juglans species
Lindera obtusiloba
Magnolia species (seed does not store very well but if need to be then cold AND moist)
Mahonia species
Pseudolarix amabilis
Quercus species
Salix species
Sassafras albidum

In my experience seeds of many members (not all!!!) of the Ericaceae, Fabaceae and Rosaceae can be stored cold and dry in a plastic container in the refridgerator (5 Celsius/41 Fahrenheit) while keeping decent germination rates for some years.

This post was edited by GardenPrince on Sat, Feb 1, 14 at 4:57