I have some tulips and daffodils that need to be moved. When is the best time to dig up the bulbs and move them? Do I have to wait until they're dormant again, or can they be moved when they're growing/blooming?
If you can wait, it's probably best to wait until the foliage has died back. But if you have to move them, as long as you leave their foliage on them and replant them somewhere so they can complete their growth cycle it may be OK, although the stress of transplanting will probably take some energy away from replenishing the bulbs for next year.
There are just a couple that are about to be run over by some rampant Asiatic lilies (who knew those things would spread like crazy?) if I don't move them. Maybe I'll try to move those and then leave the rest until they die back.
Once they finish blooming you can move them when you like, provided you leave all the foliage to die back on its own. Traditionally, when I was a kid that is(!), bulbs were always lifted once the blooms were over and hung somewhere cool and dry to die back, then replanted in the fall.
That leaves the ground clear for summer bedding without the untidy bulb foliage drooping around and is supposed to reduce the chance of "tulip fire blight" destroying the bulbs. Some bulbs, for example snowdrops are best moved "in the green" that is while they are growing. They do much better that way.