there's always a good chance to get one of the plants you crossbred, so it is better to try breeding the stickreed. don't know aboput seedpouches, but if i recall correctly, they had a chance of dropping.
was editing when you posted so will add here
also i read that resists make it harder to crossbreed? or did i misunderstand?
I am thinking breed for growth first.. then breed the quantity ? or is the quantity determine pouches?