Lobelia is a genus of approximately 370 species of annuals, perennials, shrubs, and aquatics found across tropical and temperate regions worldwide, with many originating from North, Central, and South America. This enchanting flower family encompasses remarkable diversity, from the delicate edging lobelias that cascade gracefully over container edges to the stately hybrid cultivars that command attention with their vibrant spikes of color. Hardy in zones 5 through 9, lobelias thrive in consistently moist to wet soils and bloom prolifically from July through September, attracting hummingbirds and butterflies while remaining steadfastly resistant to deer. Whether you're creating a rain garden, naturalizing a boggy corner, or designing a cutting garden, lobelias offer both ease of care and extraordinary visual impact.
Partial Sun
Moderate
5-9
36in H x 24in W
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Moderate
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Lobelias command attention through their showy, two-lipped tubular flowers that bloom in striking shades of lavender, pink, red, purple, and violet from midsummer through fall. The genus earned its name from Matthias de l'Obel, a 16th-century French physician and botanist whose innovative work on plant classification laid groundwork for modern botanical study. Deer and rabbits leave lobelias untouched, while hummingbirds and butterflies cannot resist them, making these flowers a genuine wildlife magnet. They thrive in conditions many plants find challenging, including wet soils, boggy areas, and heavy shade, while remaining low-maintenance once established.
Lobelias excel in rain gardens and naturalized plantings, where their tolerance for wet soil and heavy shade transforms challenging landscape conditions into thriving ecosystems. Their profuse, showy blooms make them exceptional cut flowers for arrangements, while shorter varieties such as edging lobelias create stunning borders and container displays. The tall hybrid forms, reaching 24 to 36 inches or more, anchor mixed perennial beds and provide vertical interest alongside lower-growing companions. Both upright and trailing varieties adapt beautifully to containers, hanging baskets, and annual bedding schemes.
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Start seeds indoors 8 to 10 weeks before your last frost date at temperatures between 65 and 75 degrees Fahrenheit. Seeds are tiny and should be surface-sown or barely covered; do not bury them as they need light to germinate. Keep soil consistently moist but not waterlogged during germination.
Transplant seedlings outdoors after the last frost date has passed, when soil has warmed and nighttime temperatures remain above 50 degrees Fahrenheit. Harden off plants gradually over 7 to 10 days by exposing them to increasing periods of outdoor conditions. Space plants 6 to 12 inches apart depending on the mature width of your variety (typically 6 to 24 inches).
Deadhead spent flower spikes regularly to encourage continuous blooming throughout the season. If plants begin to decline mid-summer (a common issue in hot climates), cut them back after flowering to encourage potential reblooming. In spring, divide established clumps to rejuvenate older plants and promote vigorous new growth. Some hybrid lobelias may self-seed, offering gardeners the choice to allow new plants to establish naturally or remove volunteers.
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“The genus Lobelia honors Matthias de l'Obel (1538-1616), a French physician and botanist whose groundbreaking work, Stirpium Adversaria Nova (1570), revolutionized plant classification by organizing plants based on leaf structure rather than previous systems. This scholarly foundation established the botanical study that would eventually place these charming flowers at the center of garden design. Modern hybrid lobelias, such as the Lobelia x speciosa group, represent intentional crosses between species like L. fulgens, L. cardinalis, and L. siphilitica, developed by breeders seeking to combine the best traits of each parent. Cultivators like Terra Nova Nurseries of Canby, Oregon have further refined the genus through selective breeding, introducing named varieties that showcase specific color ranges and growth habits while maintaining the genus's legendary appeal to pollinators.”