Do Pistachios split open by themselves when they are ripe or does a machine do that?

Answer 1

Pistachios naturally split with they are ripen on the tree.

From the website below, "As the pistachio kernel grows, it naturally expands within the shell until it splits open. Nonsplit shells usually contain immature kernels and should be discarded. "

Answer 2

um... i think they cook them to make them pop open

Answer 3

when they are roasted they pop open.