Posted: 22/03/2017 at 12:30
Rainwater on its own does not penetrate pots, especially when covered by foliage. You need to give it good, regular drinks and, whilst covered in foliage, I would add a liquid feed. You need to leave the foliage to die down completely so it can feed the bulbs for next year's flowers so don't remove it till it's faded and gone brown.
I borders, you can disguise the leaves by growing the alliums through other plants such as hardy geraniums, geums, astrantias and so on. In a pot on their own there's nowhere to hide.