Make notes about the expected height of the plants, as well as the season and color of bloom. You'll want to make note of their cultural requirements, such as sunshine and moisture, and group together plants of similar needs. Invest in a couple of reference books, at least one with good color photos, to help you in your planning. Cooperative Extension Service bulletins can be helpful in finding out what works well in your area. Like a symphony, each of the plants in your perennial collection will have its turn at playing the headliner, but then will fade back to provide a harmonious background.
Some perennials provide beauty through striking foliage or texture.
Some species are notorious spreaders, aiming to take over the entire garden. Some plants will need to be rejuvenated by dividing them every few years or so in order to keep them blooming. Dig up the plants, separate with a sharp knife or shovel, and replant where needed. Tall, narrow flower stalks or large blossoms on slender stalks may be enhanced for viewing by staking or supporting in a frame. Many garden centers and catalogs sell accessories that help these flowers stay upright.