The thing about buying sds is that we do not know how viable they are - ie - how they were harvested. I only harvest wild 'naner sds here from plts with
naturally ripen fruits. These prove to the be best for germination. You see my point?
I usually soak my sds for at least 3-5 days depending on their condition. In your case, it should be in luke warm water like jmoore putting the soak in the heated propagator. Then its your luck on how viable the sds are.
All the best
