The orientals are later bloomers and thus come up a bit later normally. Newly planted will come up later in any case. If you are concerned that they may have flooded out, you might want to chance it and dig one up to see. Without good drainage creating standing water, rotting is a possibility, but you might be okay. My potted orientals are up about 12" and this is their 2nd year, so it's possible that yours may sprout soon. One of my sisters planted some new asiatics around the end of April and they only recently emerged the past week or so (my old ones are up 2ft right now), so keep checking.

I was wondering the same thing. I planted mine about a month ago and nothing. I was thinking of digging one up to see but I don't want to damage them if they are right under the surface.