12 Important Pieces of Advice:
1 A small space is best for a perennial garden. Larger spaces need shrubs.
2 Perennials should vary in form & texture. There are many strap-leaved perennials & grasses. Too many together is boring. Put rounded leaves next to spiky ones.
3 Alternate plants of different heights, but not rigidly.
4 Limit colors to avoid chaos. Blend more than contrast. Use blue with purple, yellow with orange, pink with orange & purple, red with purple & blue.
5 Use perennials that bloom in every season. Visit nurseries often to see what is blooming. Read Bloom Times.
6 Buy 2 or more perennials in interesting color combinations when shopping. If you like something, buy more later.
9 Consider native perennials, especially in shade.
10 Do not become fixated on the number 3. Everything in triplicate looks highly contrived. Use the numbers 2, 3, 4 & 5 equally. Use 1 sparingly.
11 Understand that good design evolves over many years.
12 Visit open gardens with the Northwest Perennial Alliance, the NPA.
Read How to Make a Garden.