I have several seed viability charts for flowers and for vegetables but not a good source for the viability of herb seeds. Since it was too nasty to be outside I started a search.
Growing up in the "waste not, want not" generation it is really difficult for me to throw away anything that may still have a purpose, and especially garden seeds. However, it is a total waste of time and energy to be ever hopeful that some 6 year old marigold seeds will germinate, even at a 25% rate. I discovered that depending on type, marigolds have a viability of 2-3 years. I now feel I have permission to throw out the seeds and not feel I am being wasteful. Back in the day, I probably would have tried to do something crafty with them. Now I would rather read a book.
Apparently my computer doesn't totally understand the catch phrase I use on my searches, which is edu sites only. Even though I specifically noted "herb seed viability charts: edu sites only" I had to wade through germination tables, ideal climate charts and charts on soil recommendations. Plus many commercial sources to purchase seeds.
I did find two sources that I printed out for my garden notebook. One was from Johnny's Seeds and the other was from Snoqualmie Seed Savers.
Johnny's chart labeled as a Seed Storage Guide wasn't as informative as I had hoped. Most all entry's were classified with a range of 1-4 years viability. I had hoped for a chart more definitive from them. I have been a customer for years and always felt they did an excellent job with their cultural information. That's why I was surprised their chart wasn't more detailed.
Snoqualmie Valley Seed Exchange is a 10 year old volunteer based seed exchange located in Duvall, WA. Their criteria for participation in the donation of leftover seeds is that the seed can be no older than 3 years, or you have tested their ability to germinate. With that standard in mind, I feel confident that their definitive charts are more accurate. The chart is available at
Parsley is an example of the differences in listings. Johnny's list reflects 1-4 years, the seedsaver list is 2 years and the Iowa State Extension lists 1 year for seed viability in their cultural info on parsley.
The optimal conditions for seed storage is low humidity and low temperatures (45 degrees F). A general formula is that the sum of he temperature and % of relative humidity should be less than 100. According to Johnny's fact sheet the actual storage life will depend upon the viability and moisture content of the seed when initially placed in storage, the specific variety, and the conditions of the storage environment.
When you get right down to the nitty-gritty of life there are no guarantees. The only way to be sure of germination is to count out 10 seeds, germinate them between damp paper towels in a plastic bag. After several days check for germination to see how many have germination. If 5 have germinated, you have 50% germination.
Be sure to listen to the Gardening: Get Good at It "Winter Chores" segment on Tues. Nov. 17 on KPOV 88.9 FM between 9-9:30 am.