I have been asked about how to use iris in the landscape and I must confess I had never thought much about it. Looking back, I remember my grandmother had an iris bed, about 6' by 6' outside the back door. I remember how amazing those purple, yellow and brown flowers were when they were in bloom, but also how intimidating that bed was to a young child when they were not in bloom!
Although I like the stiff, sword like foliage as a contrast to soft, round foliage in the garden, when grown alone, they look like a bed or swords sticking out of the ground. Not very pretty or inviting.
I like to grow them in front of a large shrub that will set the blooms off nicely my creating contrast and a pleasing background.
I have always mixed iris in with other plants, mainly because they bloom such a short time that there needs to be other interest to make the bed attractive the rest of the year.
I use them as focal points, fully integrated into a complex combination that includes other plants with similar cultural needs like daylilies and roses. They are a good mid-size plant that makes the bridge between taller shrubs and low-laying groundcovers quite nicely. These in my SJC garden are only a couple years old and haven't developed the large base of foliage and multiple stems that they will in years to come. I look forward to that display someday, but I am thrilled with what I have now too!