Lobelia
Lobelia erinus
Edging lobelia is a low, mounding or trailing annual smothered in tiny, intensely blue flowers from spring to frost. It's a staple of hanging baskets, window boxes and bedding borders.
- Light
- Full sun to part shade
- Water
- Keep consistently moist
- Difficulty
- Easy
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Overview
Lobelia erinus is a tender, low-growing annual (perennial in frost-free zones) celebrated for clouds of small, vivid flowers in cobalt blue, violet, pink or white. Compact forms edge beds and borders, while trailing forms spill from baskets and containers.
The genus Lobelia is large and varied, also including tall perennials like the scarlet cardinal flower (L. cardinalis) and great blue lobelia (L. siphilitica). The common garden lobelia is prized for its long, profuse bloom in cool conditions.
How to identify it
Tiny two-lipped flowers and a dense habit identify garden lobelia.
- Flowers: small, fan-shaped, two-lipped blooms, often with a white or yellow throat; classic deep blue plus violet, lilac, pink and white
- Leaves: small, narrow, alternate, sometimes bronze-tinged
- Habit: low mounds 4-9 in tall, or cascading stems in trailing varieties
- Overall: fine-textured plant that becomes a solid sheet of color in full bloom
Care & growing
Lobelia rewards cool, moist conditions and may pause in midsummer heat.
- Light: full sun in cool climates; part shade where summers are hot
- Water: keep consistently moist; it wilts and stalls if it dries out
- Soil: rich, well-drained soil high in organic matter
- Temperature: prefers mild temperatures; flowering slows in extreme heat
- Feeding: regular light feeding sustains container plants
- Maintenance: shear back leggy or heat-stalled plants to spur fresh bloom
- Propagation: from very fine seed sown indoors in late winter
Habitat & origin
Lobelia erinus is native to southern Africa, where it grows in moist, sunny and lightly shaded sites. It has been bred into countless garden cultivars.
It is grown worldwide as a cool-season bedding and container plant, performing best in spring, early summer and autumn, and in regions with mild summers it can flower continuously.
Uses & benefits
Garden lobelia is used as an ornamental annual for color and edging.
- Containers: a mainstay of hanging baskets, window boxes and mixed pots, especially trailing types
- Bedding: low edging along paths and borders
- Ecological: small flowers attract bees and other pollinators
- Caution: like other lobelias it contains alkaloids and is toxic if ingested
Frequently asked questions
Why did my lobelia stop blooming in summer?
Heat is the usual cause. Shear it back by about a third, keep it watered, and it often rebounds when cooler weather returns.
Sun or shade for lobelia?
Full sun in cool climates; in hot regions give it afternoon shade and steady moisture.
Is lobelia a perennial?
Garden lobelia (L. erinus) is treated as an annual in most climates but can survive as a tender perennial where there's no frost.
How do I keep basket lobelia full?
Water consistently, feed lightly, and trim straggly stems. Even moisture is the single biggest factor in keeping it lush.
Lobelia guides
In-depth guides for identifying, growing, and caring for Lobelia.
