Spring has arrived and what a welcome visitor she is! She will stay for just a few weeks, then quietly leave to make way for her hotter, flashier sister. For now, she will parade her spring fashions in shades of yellow, green, and white.

When summer arrives, what colors will she wear in your garden this year? I have my old standby favorites: tall purple and yellow bearded irises, maroon and pink astilbe, and the deep bluish-purple of false indigo. Later, golden coreopsis, gaillardia, and rudbeckia will have their turn, joined this year by purple anise hyssop and cherry red meadow sage.

Each year, I try to add two or three new perennials to the beds. This spring, we are in the process of removing English and lemon thyme plants that have served the garden well as edging, but have grown woody and out of control. The borders of the beds look bare without the pretty thyme plants spilling over onto the pavement.

A potential replacement for the thyme is Sedum spurium “Schorbuser Blu...