A word about nitrogen. Many years ago Fred Meyer told me that amaryllids
like Hippeastrum and many others (but not so much hardier fare like Crinum
or Narcissus) resent N in the form it typically appears in fertilizers: as
ammonia or urea nitrogen. I made the switch to orchid fertilizers such as
Dyna-Grow years ago just to get N comprised of mostly nitrate nitrogen,
with
a small percentage of ammonia nitrogen. I bloomed some difficult bulbs
when
I did this, plants that had not flowered for 10+ years previously
(Hippeastrum parodii, Paramongaia, etc.). Nitrate nitrogen is worth the
moderate extra cost in my view and it is not difficult to find brands that
use it.