This is what my client sees when she comes home from vacation. She doesn't see the soil strewn all over the terrace or the clumps of perennials lying on their backs, roots in the air. She doesn't see me sawing into their rootballs, breaking iris into clumps small enough to tuck in between and among the new plants I'm adding today.
My client is away for a month and I've been making lots of changes, hoping to delight her with a rejuvenated terrace when she returns. This is a moonlight garden; it's used at night, in the dark, after work. So I focus on white flowers, white foliage, anything that glows in the dusk while my client enjoys a glass of wine on her terrace after a long, hard day.
White crepe myrtle, white rose of sharon, rosa rugosa, caladium, begonias, lantana, hydrangeas, mandevilla, Siberian iris, and a new favorite, Calocephalus. Then a few spots of contrast to make the white pop: the chartreuse, finely cut leaves of staghorn sumac 'Tiger's Eye', the purple foliage of Physocarpus (aka ninebark).
And here's somethinng I learned today, maybe you can benefit from my experience. Ilex verticillata (winterberry) does not belong in a small container with other perennial plants. The roots of one small I. verticillata were hogging the nutrients in the planter box, starving its companions. I dug out the neighboring perennials and pruned the roots of the I. verticillata by 2/3. Then I added new soil to the box (Fafard, of course) and filled in with annuals. I figure annuals won't suffer from long term starvation since they're only around for a single growing season.
The leaves of 'Tiger Eye' (a Rhus typhina hybrid) underplanted with the groovy annual Calocephalus. Both do best in full sun.