In recent years plant breeders have created ever blooming and repeat blooming perennials: Iris, daylilies, and, of course, roses. There is certainly something nice about repeat bloomers. For example, I had yellow Iris blooming in late November last year and cut some for the Thanksgiving table.
That said, I worry that the lure of repeat blooming trait may cause us to leave behind once bloomers that are in every other way vastly superior plants. Truth is that the color of that yellow, repeat-blooming Iris doesn't begin to compare with the clarity and intensity of once blooming varieties. Similarly, repeat-blooming daylilies, such as Stella De Oro, doesn't hold a candle to almost any of the once blooming varieties.
You can see where we may be heading if you consider that in the rose world most once blooming varieties have been discarded by the nursery trade in favor of repeat bloomers. Fabulous old roses such as Madam Hardy, which is, to my mind, the finest white rose ever with hundreds of perfect petals surrounding a green eye, are very hard to come by. Why? Because it only blooms once.
Yet, no one would think Forsythia or Peonies are not worth planting because they ony bloom once. So in my garden, I've planted a couple of once-blooming roses: Harrison's Yellow and Charles de Mills.
Sure, I grow repeat blooming roses. I also plant annuals to maintain color in the garden. But I mostly treat my perennials and shrubs like fireworks. They throw up a flush of bloom for about a week or so. For the week they pop, they are amazing and, then they fade into the green of the garden. Part of the art of garden design is arranging a succession of bloom and pairing plants that bloom together. One can stretch the bloom season of, say Peonies, by selecting early, mid and late blooming varieties. If one also plants tree peonies, which bloom about two to three weeks before the herbaceous, one can stretch the bloom season even longer. Planting this way ensures that the garden always has a new explosion of color to enjoy.