If you planted in May - consider this is only June. Since you only mention Siberian iris, which grow from a rhizome rather than a bulb, you may see some leaf growth this fall, but they wouldn't bloom until probably May/June (or whenever they normally bloom in PA) of next season at the earliest. Here where I am, my old Siberians are just starting to do their yearly blooming - which is normal for my location.

Perennials, unlike the colorful annual plants which give instant gratification, take time unless you purchase fully grown specimens.

If sold as bare root 'bulbs', which many rhizomatous or fleshy rooted perennials are, it may be that the package dried out and the dormant plants died. These packaged so-called bulbs are massed produced and marketed and are often not stored properly or given even basic care. Typically the success rate of these items is low so don't take it personally :-))

In my area, Siberian iris are sold as started plants in May - not bare root or dormant - and are in bloom in early June.