Think of allium bulbs as another spring bulb. Alliums tulips daffodils, hyacinth. They all pretty much work the same way. After the flowers fade, the leaves will remain for a few weeks to gather energy for next year & the bulbs divide. When the leaves yellow & shrival, you can dig them up to move them. Yes you can put a potted plant over them.

If you cut the dead flower stems off you can dry them and use them in arrangements. They take a gold spray quite well too.

quite often the leaves die back just before the flowers open. [causes a lot of consternation when people see the leaves turning yellow before the flower] cut the spent flower head off and yes you can put something over the spot. I actually plant a perennial next to it so I know where they are the following season.

thanks, Bathgate, Teragram, and Seaburngirl..all this info is very helpful..just what i needed to know..