Big plants! How to fit them in?

Angelica gigas, a three- to six-foot herb, belongs to the same family with carrots and parsley, and has pompom-shaped flowers with the family's delicate, umbrella-spoke structure. In contrast to green leaves, the stems and flowers are a deep reddish-purple. It loves shade and deep, moist soil — but is versatile. I grew a plain-colored variety once, but I yearn for that high contrast.

False Aster (Boltonia Asteroides) also six feet, from July to September is covered with 3/4-inch flowers that look like asters, with yellow centers and white ray petals (sometimes lilac or pink). It likes sun, but will grow fine in part sun; you just might have to restrain its stems from flopping. Soil? Moisture? Not fussy at all. I once bought a pot of this at a great sale price, then when I got it home realized I had no room — and had to take it back. Haven't gotten over it.

Artemisia lactiflora grows blackish-green leaves to three feet, and then on top of that, in late summer to mid-fall, another two feet of branching, lacy plumes of creamy-white flowers. It likes full sun, and moist, well-drained soil. A plant with pizazz — but the variety I crave, 'Guizhou,' (purple ghost plant) has even more: pure white flowers, with mahogany-colored stems and a purple flush on young leaves.

Tree peonies, unlike most peonies, have woody stems; they grow, in ten years, to five feet tall and wide. Although you can prune them to a single stem, it's chancy, because old stems die and new ones sprout all the time. Their natural (and healthiest) shape is a little cluster of stems rising to a broad canopy of leaves — and, in early summer, flowers: some of the most glamorous you can imagine, in white, yellows, pinks, reds, and combinations.

They're easy to please: well-drained soil, half a day of sun (they'll be happy with more, but the flowers will fade faster). They're very long-lived — some in China are 500 years old. But they don't like being transplanted, and they're expensive. No playing musical plants with this one. I need to find a spot where ten years from now there will be space for a five-foot cluster ... and where right now the fledgling shrub will be visible (and get sun) though it's small. A puzzle I haven't solved yet — but I'm dreaming on it.

• Tree Peonies — from Golden Port International. This site is extensive, the plants are expensive, and they don't even bother to give botanical names, just the Chinese. This page tells more about the plant.