I wouldn't fertilize while it's breaking dormancy or in budding. But 'conventional wisdom' says for the three months after bloom, regular fertilizing is the most important thing you can do, if you wish it to bloom well next year. Some give it a gentle fertilizer while in mid-bloom, but I usually wait. Mine spend the summer outside. As long as they have leaves, I fertilize them (half-strength) monthly until late summer, and as cooler fall weather approaches- then I reduce fertilizer and water in preparation for winter dormancy in my area.
Minerva, one of my favorites! And if the Hippeastrum (AKA amaryllis) doesn't make it until next year, there's no shame in that!
