Spiderworts for the Home Garden
Although the origin of the common name spiderwort has been lost, the sticky sap from cut stems does dry to form silken strands like those of a spider web. The spent flowers dangle on petioles like spider legs. The scientific name, Tradescantia, comes from the botanists and gardeners for King Charles I of England, John Tradescant and his son John. All spiderworts, over 85 species, are native to the Americas, both tropical and temperate areas. They are members of the Commelinaceae, the dayflower or spiderwort family.
I've known spiderworts all my life. My mother's houseplant inventory included Moses-in-the-Cradle (Tradescantia spathacea, formerly Rhoeo discolor). This plant grows in a tall rosette with attractive, lance-shaped leaves. The upper surfaces of the leaves are dark green with magenta-purple undersides. A purple cradle-shaped bract encloses the white, three-petaled flower clusters. As the seeds matured, my mom dropped the papery cradle onto the surface of the potting media. After the seeds germinated, she shared the seedlings with friends.
A trailing spiderwort is Tradescantia pallida (formerly Setacreasea purpurea), commonly called inchplant or wandering Jew, which does well as an annual bedding or container plant. 'Purple Heart' and 'Purple Queen' have violet-purple leaves and light purple flowers. They do best in rich, moist, well-drained soil in shade to partial sun.
Tradescantia fluminensis (formerly T. albiflora), a similar trailing plant, the small-leaf spiderwort, sometimes also marketed as inchplant, thrives in indirect light as a container or hanging basket plant. Hummingbirds visit its flowers. The variety 'Nanouk' has upper leaf surfaces of green and white with magenta-pink undersides. The flower buds are pink, followed by white petaled flowers. This plant is easily propagated by stem cuttings.
When someone mentions spiderworts, most gardeners think of the herbaceous clump-forming perennial garden plant. Tradescantia virginiana and T. ohiensis are native to the eastern and central United States. Both thrive in USDA Plant Hardiness Zones 4 through 9, in moist soils, but enjoy protection from hot afternoon sun. They do well in rain gardens as they tolerate short dry spells. These species may spread aggressively by underground runners and seeds, so select a site with that in mind. Usually, the three-petaled flowers are shades of blue. After blooming in May and June, the 1 to 3 feet tall grass-like foliage often becomes straggly and may flop. To prevent this, cut back the plant to about 2 to 3 inches in early July. New growth appears promptly, followed by a second flush of flowers by September. If you want a carefree planting, mask the unkempt foliage by installing companion plants around the spiderworts. Butterfly milkweed (Asclepias tuberosa), whorled milkweed (A. verticillata), and scarlet beebalm (Monarda didyma) are good options.
Growers, including Edgar S. Anderson, have created the Andersoniana group of hybrid spiderworts. These plants are complex combinations of Tradescantia. virginiana, T. subaspera, and T. ohiensis. Often, they are given the designation of Tradescantia x andersoniana. These hybrids are more compact, more tolerant of sun, and maintain neater foliage after blooming. The flowers may be white or pink, as well as traditional shades of blue. 'Sweet Kate' has lavender-purple blooms above yellow-chartreuse leaves. 'Charlotte’s Web', a nod to the E. B. White novel about a spider, has soft blue flowers and gold leaves that do not scorch in full sun.
Spiderworts are rarely bothered by pests or diseases. Usually, they are resistant to deer damage. Insect pollinators and hummingbirds are regular visitors. With all of the different species and varieties, there is a spiderwort for you.
