Some common names for these seldom-grown, showy perennials include Hardy Gloxinia and Chinese Trumpet Flower. A favorite in old English gardens, these hardy and nearly hardy perennials are native to high elevations in India, Tibet, China, and Turkestan.
Sometimes it is best to treat them as short-lived perennials but it is well worth the extra effort to grow these plants. They are not a gesneriad or related to gloxinias, but rather to the Campsis and Bignonia family or trumpet vines. The plant is named after an 18th-century Jesuit missionary.
The crowns are easily damaged and plants are very late to emerge in the spring, so it is recommend that you mark where they’re planted. If you are careful in the spring and don’t disturb them, you’ll be rewarded with a clump of exotic looking flowers for years that will amaze visitors to your garden.
Incarvillea is a beautiful plant with low growing clumps of glossy, deeply divided leaves from which arise 12 – 24 inch leafless stems topped by clusters of flowers, each of which may be as much as 3 inches across. The first few blooms on each plant often appear before the rosettes of mid-green leaflets have fully developed.
Blooming from mid-spring to midsummer, the large terminal heads of exotic trumpet-shaped flowers are a bright magenta to rosy-pink, with yellow throats and are held well above a rosette of dark green foliage on stout stems. ‘Snowtop’, a white-flowering variety is also available.
Hardy gloxinia’s can be used as an accent plant or to add a bright splash of color in the border or rock garden. They work well along the east side of buildings where they would receive good morning sun, but be sheltered during the winter.
Plant them with other summer bloomers such as Lilies, Veronica, Penstemon, and Campanula. Remove flowers as they fade to extend the blooming season.
Grow Incarvillea in deep, sandy soil that has been liberally enriched with compost or leaf mold. They need consistent moisture while in bloom, but good drainage is essential during the dormant winter season. Protect the young growth from slugs.
Crowns should be buried 3-6 inches below soil level and spaced 12 to 15 inches apart in a area with full to part sun that is protected. Plants should be mulched in the fall with dry straw or some other mulch, to protect the crowns from winter winds.
Seeds may be sown in the spring or autumn in sandy soil in a cold frame or they may be sown in flats of soil outdoors and covered with sheets of glass. Seeds need no pretreatment but need light to germinate. Do NOT cover. Takes about 14 days to germinate with soil temp at 60-65° F.
Crowns must be protected in winter with mulch or compost or in colder zones, they may be lifted and stored over winter in a cool, dry place. It is possible to divide and reset clumps, but the plants flourish most vigorously if allowed to remain undisturbed.