>> So one question, do you think that among the seeds i can harvest
(tomatoe, cucubitaceae,sunflower), some could be more convenient for dry
condition, even after just one season?
- You could better refer to your neibourghood to fine local adapted seeds.
Or browsing on the Kokopelli catalogue to find seed wich originate from a
similar wether than yours.
>> another do you throw seed ball of solanaceae before or after winter?
- In your case and wether, I would have done it after the winter (to avoid
that the ball decompose and offer the seeds whithout protection to a
possible rotting process with wetness and freezing situation but before the
dry season to permit the clay to wet and give the seed the opportunity to
prout on its time...
Good luck for your project.
(I lived before in the northen part of th french Alpes)