It's worth trying but also have a back-up plan.

For example, I did try some jalapeno seeds from 2012 this year. They germinated in the wet paper towel method, but not in direct planting method. So it could be some other conditions in the direct planting but I also did several seeds per container, and none came up, not even to germinate and die later due to my own carelessness :-(

So just have the backups in case they are needed! :-)

The viability of old seed varies by plant type. There are charts out there with information. I have linked to one.

The one I linked to says kohlrabi lasts a maximum of 3 years, though, so...

--McKenzie

Here is a link that might be useful: Vegetable Seed Viability

From the Millennium Seed Bank FAQ:
"Not surprisingly, few longevity experiments of any age that mirror seed conservation storage are available for us to study today. However, in 1987, samples of cereal and weed seeds were germinated that had been placed within sealed glass vials in Vienna 110 years earlier (reported by Steiner & Ruckenbauer in 1995). One of the aims of the Millennium Seed Bank Partnership is to set up a carefully controlled set of longevity experiments that future generations can study.

That's nuthin' compared to the 24,000 year old mung bean, of course.

(Personally, I think seed sellers encourage us to want fresh seeds and 100% germination. When you have older seed, and just want a few plants, 25% germination is fine ....)

This is also good:
"An interesting story relates to seeds of the legume Albizzia julibrissin on a pressed herbarium specimen collected from China in 1793 and deposited in the British Museum. This specimen was 'watered' while a fire was being extinguished in 1940 and several seeds (at least 147 years old) germinated.

... we'll see how well stored my old snow pea seeds are. They're about 15 years old, and I plan on trying them this fall.