I got some Daubenya seeds from the seed exchange in 2013 , sowed them ( 5 seeds ) , nothing . They were put in the corner of the greenhouse and forgotten about .
In September or October 2018 I noticed seedlings , 5 , 100% germination . I didn't water them I watered something else and it dripped into them .
I think they stay viable for a while.
They germinated when things started to cool down .
I showed some Zeyheri seeds 3 years ago , they lay all summer and sprouted in sep/oct too . They didn't reappear the next year though so I got some more , these haven't germinated yet but I'm not throwing them out .