Certified GKH Gardening Expert
This number varies from plant to plant. Some seeds, such as Colocasia, will fail to germinate within minutes of drying out completely, where as some bean species will lasts for hundreds of years if stored properly.
The only way to know will be to make an attempt at germination! You may be surprised at what will come up after that long.
Correction...that should have been "more than 10 years old", not 19 years.