It’s not that astilbe are uncommon, it’s more that they’re under-rated. They handle full shade, clay soil, and wet feet, all the while offering a beautiful splash of color. As a general rule, the cooler the climate the more sun they can handle…alternatively, try to avoid too much sun in hot, humid climates. The leaves are soft, almost resembling a fern, and flowers are usually in shades of red, pink or white. If flower stalks are left on the plant they can provide nice winter interest, or they can be cut, dried, and used in floral arrangements. The plants require very little maintenance and can be multiplied every few years by division. Astilbe are wonderful companions to other shade plants like hosta, heucheras, or ligularia.
Brunnera has distinctive heart-shaped leaves and very small flowers. It is a groundcover that does well with some shade. If you have a variegated variety, it will probably need more shade to avoid scorching the leaves. The roots of the species plant can be used to make a red dye, while all parts (leaves, stems, flowers and roots) have some traditional medicinal uses. However, I can find no report of cultivars being put to such use. The plant is also commonly known as Siberian bugloss, as it originates from Eastern Europe. If anyone knows the story behind the name bugloss, please let me know.