Incarvillea (Incarvillea delavayi)
Discover Incarvillea delavayi, the Hardy Gloxinia. This striking perennial offers pinkish-red summer blooms in Zones 5-7.
Complete Plant Information
Overview
Incarvillea delavayi, frequently known as Hardy Gloxinia, brings exotic structure and surprising summer color to the perennial border. This clump-forming plant commands attention with trumpet-shaped flowers borne high above the foliage on sturdy stalks, making it a unique focal point in the garden. Its visual appeal is enhanced by the contrast between the delicate, fern-like leaves and the robust, colorful blooms.
Cultivating Incarvillea successfully relies on mimicking its native environment in Southwestern China. It thrives in average, well-drained soil, provided it receives consistent moisture, particularly during its active growing and flowering period. While it appreciates full sun, locations experiencing intense summer heat benefit greatly from afternoon shade protection.
Gardeners seeking distinctive vertical interest will appreciate Incarvillea delavayi for its architectural summer display. Although the plant demands medium maintenance to ensure optimal health, the reward is a long-lasting show of unique pinkish-red flowers. Ensure your location falls within USDA Zones 5 through 7 for the best chance of perennial survival.
Fast Facts
- Plant Family: Bignoniaceae
- Plant Type: Herbaceous perennial
- Native Range: Southwestern China
- Hardiness Zones: USDA Zones 5-7
- Size at Maturity:
- Height: 1.5-2 ft
- Spread: 1.5-2 ft
- Bloom Time: July to August
- Bloom Description: Pinkish-red with yellow throat
- Sun Exposure: Full sun to part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
Planting stock of Incarvillea should be situated in spring or early fall, provided the soil is well-drained. The ideal location offers excellent drainage, as stagnant moisture around the unique tap root can quickly cause rot. This perennial prefers deep, moist, sandy soils, especially when situated in full sun.
Ongoing care requires attention to consistent moisture levels; aim for medium watering throughout the growing season. Deadheading faded flower clusters is recommended to potentially prolong the overall bloom period into late summer. Be cautious; Incarvillea is intolerant of the high heat and humidity prevalent in the deep Southern US, often requiring afternoon shade there.
Division of established clumps is challenging due to the structure of the carrot-like tap root, so site your plant where it can mature undisturbed. Gardeners in the northern limits of Zone 5 should take precautions against severe winter cold. Mulching the crowns generously with straw before deep freezes arrive helps insulate the root system, ensuring the survival of your beautiful Incarvillea delavayi into the next season.
Landscape Uses
The architectural presence of Incarvillea delavayi makes it an excellent candidate for structured placements within the garden design. Its height (up to 2 feet) allows it to stand proud yet not overwhelm shorter companions. It performs exceptionally well when positioned towards the middle or back of mixed perennial borders where its unique flower spikes can be easily observed.
For smaller spaces, Incarvillea is highly recommended for rock gardens, where the sharp drainage mimics some of its ideal mountain habitats. Pairing it with plants requiring similar moisture and sun levels, such as Oriental Poppies or ornamental grasses that offer contrasting texture, enhances display quality without creating cultural conflicts. Use these plants to frame the vibrant flowers of the Incarvillea.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Incarvillea delavayi, commonly called hardy gloxinia, is a clump-forming perennial which typically grows 18-24” tall. Features clusters of trumpet-shaped, pinkish-red, 2.5” long flowers with yellow throats (5-12 flowers per cluster). Clusters appear in summer atop sturdy, essentially leafless flower stalks which extend well above the basal, arching, fern-like, pinnately compound, medium green leaves (to 12” long).
Tolerances
- Slugs are frequent visitors
Potential Problems
Slugs are a primary concern for gardeners growing this species. These pests are frequently attracted to the tender growth of Incarvillea foliage and developing flower buds. To manage slug populations effectively, maintain good garden hygiene by removing hiding spots like heavy debris. Applying slug bait pellets around the base of the plants or utilizing copper tape barriers can deter them successfully, protecting your Incarvillea display.
Frequently Asked Questions
What hardiness zones is Incarvillea suitable for?
Incarvillea delavayi is generally suitable for USDA Zones 5 through 7. Check local conditions, especially at the colder end of Zone 5, and provide adequate winter mulch protection.
How large does Incarvillea grow?
This herbaceous perennial typically reaches 1.5 to 2 feet in height, spreading to a similar width of 1.5 to 2 feet at maturity.
When does Incarvillea bloom?
Incarvillea blooms during the summer months, specifically from July through August, showcasing gorgeous pinkish-red flowers with distinct yellow throats.
What sun exposure does Incarvillea need?
This plant performs best in full sun to part shade conditions. Gardeners in warmer climates should ensure it receives afternoon shade to prevent scorching during summer heat peaks.
Conclusion
Incarvillea delavayi offers a distinctly valuable addition to the mid-summer garden with its tall, vibrant, trumpet-like flowers. Its unique foliage texture and flower form make the Hardy Gloxinia a true conversation starter. Before planting, confirm your USDA zone compatibility (5-7) and ensure well-drained soil to guarantee a successful, low-fuss perennial display.
Companion Planting Strategy
Selecting suitable companions for Incarvillea delavayi helps manage its medium water and sun requirements while visually complementing its unique upright habit. Consider pairing it with spring-blooming bulbs that fade just as the Incarvillea begins to emerge, extending the season of interest. Good partners include bearded irises or early-flowering peonies, which share a preference for well-drained soil conditions.
When choosing summer companions, look for plants that provide visual contrast without competing too aggressively for moisture from the Incarvillea’s deep root system. Low-growing, silvery foliage plants work beautifully at the front of the border, drawing attention upward towards the pinkish-red blooms. Remember that if placed in the hottest part of the garden, companions should also tolerate or appreciate some dappled afternoon shade.
Seasonal Care Calendar
Spring cleanup for Incarvillea involves removing any protective winter mulch once the danger of hard frost has passed and new growth is visible. Water deeply and consistently as the weather warms, focusing moisture at the soil level rather than overhead to discourage fungal issues. This is the ideal time to amend the soil lightly with organic matter to maintain those preferred deep, moist, sandy conditions.
During the summer blooming period, deadheading spent flowers encourages repeat blooming, keeping your border vibrant longer. Monitor slug activity closely during damp, mild evenings and take preemptive action. By mid-to-late summer, as the foliage begins to yellow naturally, cease heavy watering as the plant enters a partial dormancy cycle, preparing for winter.
Winter preparation is crucial, especially in Zone 5. Once foliage dies back, apply a thick layer of straw or dry leaf mold over the crown area to insulate the vulnerable taproot from freeze-thaw cycles. Avoid adding heavy, wet compost at this time, which can smother the crown. Do not disturb the roots by attempting division in the fall.
