Cobweb Spiderwort Tradescantia sillamontana

Cobweb spiderwort is a low-growing, perennial groundcover plant that is native to dry regions in northeastern Mexico and is a member of the spiderwort family (Commelinaceae). It is densely branched, has prostrate and ascending stems, and grows 6 to 12 inches tall and 12 to 18 inches wide. The specific epithet, sillamontana, is a Latinization of "Cerro de la Silla." This references the hill or mount near Monterrey, Nuevo Leon, where this plant is native.

This plant is easy to grow and prefers partial shade but will tolerate full sun with good soil moisture. When located in an area that receives full sun in the heat of the day, the leaves can burn. It can grow in a range of soil and pH conditions; however, it prefers well-drained acidic, loamy soils. As a houseplant, it should be grown in bright, filtered light, and preferably use a loam based potting mix. Water the plant moderately during the growing season and sparingly during the winter. It is winter hardy in zones 10 to 12. Pinching the tips back will promote a bushier habit. It can take on a trailing habit if the tips are not pinched. After flowering, cutting back the plant will promote a second bloom, as well as preventing self-seeding. This plant is drought and humidity tolerant. It can be propagated by stem cuttings.

The cobweb spiderwort has stems that are densely branched, fleshy, and can grow up to 16 inches long. The stems and the leaves are covered with white hairs. The leaves are a dull olive-green to grayish-green, ovate, up to 2 inches long and 1 inch wide, and have a purplish hue in full sun. The undersides of the leaves are reddish-purple. The flowers appear in the summer and are solitary, bright  purplish-pink, 3-petaled, and  measure about 0.75 inches wide.

Although considered a tropical perennial, it can also be grown as an annual groundcover in locations that are in cooler hardiness zones. This plant works wonderfully in containers, hanging baskets or as a garden accent. 

Quick ID Hints:  

• stems densely branched and covered with dense white hairs
• leaves are in a precise geometric shape, olive-green to grayish-green, ovate, 2 inches long, 1 inch wide, covered with white hair
• solitary pink-purple to magenta, 3-petaled bloom, less than 1 inch wide

Insects, Diseases, and Other Plant Problems: Monitor for aphids, spider mites, thrips, mealybugs, snails, and caterpillars. Root rot can occur from overwatering. Leaf scorch can result from too much direct sun. Reseeding can be an issue that is best avoided by cutting the plant back after flowering is completed. 

Be aware that the Cobweb Spiderwort is toxic to humans and pets, if ingested. Keep this plant out of reach of children and pets. This plant can also cause skin redness and irritation from handling. Wear protective gloves. 

More information on Tradescantia.