When I selected my initial perennials for perennials for the space, I did not take into account soil pH and sunlight needs, and I was consequently disappointed when the purple fountain ornamental grass I planted did not return. The next year I went with some Stella d'oro lilies and some bright red Asiatic lilies. In the center I added a Rose of Sharon plant, and during the spring there are some daffodils and tulips for early color.
Of course, it was another two years before the plants in this space filled out to the point where I achieved something like a wall of color. Thus, this garden took about four years to emerge as a colorful source for peaceful contemplation, though the happy accidents are more fun than simply filling the space with a bunch of annuals each year.