sangel said:
chilling is not needed ? I can plant them immediately ? Can I store them for later ? for how long ?
No, no chilling is needed, infact I guess they won't survive cold, as Hippeastrum are tropical.
I always sow immediately, but species seed I received from abroad (mostly Brazil) aged at least a moth, still grow perfectly.
Still I do not recommend both chilling or keeping for long term. However you can try for an experiment, and if you do, please report back since I also wish to know.