I've heard the potency varies quite a bit by location and season for the same plant.

There's apparently a season when they are most potent. I would like to know what time of year that is.

The mature seeds are said to be the most potent. So whatever time of year the seeds are mature, that’s the time to buy them.

SWIM has had seeds that were extremely potent and nearly side effect free. And others that only produced side effects and nothing else, all from the same vendor at different times of year. SWIM hasn’t been keeping a log of that though.