Don't those look pretty! Petunias will give you a lot of bang for the buck. Zinnias come in different heights. I partiicularly like 'Profusion Cherry' - the small blooms are prolific and the plant branches & grows til fall.

I've never tried those irises, but from growing Tall Bearded ones I can tell you that irises should not have yellow tops to their leaves. Right now they should not be blooming yet, though yours should be a little closer to producing the stem in Baltimore. The stem of a tall bearded iris comes from one of the spiky leaves that might seem a little fuller than the others. If the tops of the leaves are turning yellow though, you may not get a bloom. Usually yellowing means you have a water issue (too much or too little). If they're bulbs and not rhiozomes, they probably have different growing requirements. I'm sure some of the experts at the American Iris Society would be happy to help you whether or not you're a member. They have local organizations as well so you might find someone in Baltimore even.

As for annuals, I love Lantana. It comes in a bunch of different colors, and smells like citrus. Pansies are great for borders, and Mandevilla is a gorgeous vining plant that will soak up as much sun as you can give it. Lots of people have it climb on mailboxes and trellises. I have mine potted so I can winter it over indoors and keep it as a perennial.