I have planted Hippeastrum 'Red Lion' (32/34 size), 60 cm deep. This means the top of the bulb from the soil level. It survived in Z5a, but never flowered. It was in half shade in a very damp location. Leaves emerged in mid August. It came back the second year, but not in the third. After this experiment i have never tried it outside. Regards, Janos Hungary