Selecting plants for a large perennial design comes down to the three Bs: big, bold, and bright. It's important to keep the plants in scale with their setting, so the dainty ground-huggers aren't going to do the job. You need large bushy plants, or at least substantial groupings of smaller perennials, to make an impact. Large leaves and flowers also help to keep the plants in proportion with their surroundings. And because you'll be seeing the planting from some distance, you'll want lots of bright color so the bed or border doesn't blend into the background.
Now, all this is well and good, but unless you have an unlimited plant-buying budget, just how are you supposed to afford all of the big, bold and bright perennials you need for a new planting? Here are a few ideas.
Investigate options for buying at wholesale nurseries in your area.
Stick with older, tried-and-true cultivars.
Purchase one or a few pots of each perennial you want, then grow them in a "nursery bed."
Grow them from seed.