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How to Grow Trailing Lobelia: The Complete Lobelia Flower Guide

Edging Lobelia., Trailing Lobelia, (Lobelia erinus) in garden, Moscow region, Russia
Photo Credit
Nick Pecker
Botanical Name
Lobelia erinus var. pendula
Plant Type
Flower
Sun Exposure
Part Sun
Soil pH
Slightly Acidic to Neutral
Bloom Time
Spring
Fall
Flower Color
Blue
Pink
Purple
Red
White
Hardiness Zone
9
10
11
Special Features
Attracts Butterflies

Planting, Growing, and Caring for Trailing Lobelia Plants

Tim Goodwin
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Trailing lobelia is for its cascading growth and colorful blooms. It thrives in cool weather, producing blue, pink, purple, red, or white flowers. While it may decline in hot, humid conditions, regular pruning can encourage new growth. Best grown as an annual in most climates, lobelia adds vibrant color to hanging baskets, containers, and garden edges. Learn more about adding Lobelia to your life!

About Trailing Lobelia

Lobelia erinus var. pendula is a trailing cultivar that puts on its best show from late spring to early summer when temperatures are cool. It blooms in shades of blue, pink, purple, red, and white. When summer’s heat and humidity roll in, this beauty takes a break. Foliage and flowering decline significantly but, with pruning and relief from the heat, may return in early fall for an encore performance. Look for heat-tolerant cultivars.

Trailing lobelia is a tender perennial winter-hardy in Zones 9 to 11 and treated as an annual elsewhere.

Lobelia erinus flower (edging lobelia, garden lobelia or trailing lobelia) hanging on iron wall hanging flower plant pot bracket outdoors in garden in beautiful sunny summer evening.
Photo: HelinFoto
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Planting

Purchasing seedlings is recommended. 

Starting from seeds can be difficult: Seeds should be sown in seed-starting mix 8 to 10 weeks before the last spring frost date. Do not cover with soil, as light aids germination. Water from the bottom to minimize the risk of damping off. Maintain a temperature of 70° to 75°F; seedlings emerge in 14 to 21 days, and blooms appear in 4 months.

Lobelia tolerates most slightly acidic soil types, but transplants will do well in potting mix amended with organic matter. Good drainage is essential.

Growing

In warm to hot and/or humid regions, provide partial shade; where summers are cool or hazy, trailing lobelia can take more direct sun.

Water to keep soil evenly moist. Apply a balanced liquid fertilizer every 2 to 3 weeks.

Pinch tips to keep plants bushy. Cut stems back by half after its first major flowering to encourage new blooms. To avoid midsummer dieback as heat and humidity set in, cut plants back to promote a fall bloom.

Varieties
  • Lobelia erinus var. pendula ‘Blue Cascade’: true blue blooms over pale foliage
  • L. erinus var. pendula Cascade Mix: blooms in shades of blue, lavender, rose, red, and white
  • L. erinus var. pendula Fountain series: large, early flowers; ‘Crimson Fountain’ blooms in deep red
  • L. erinus var. pendula ‘Sapphire’: electric-blue flowers with white eye
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Pests/Diseases

Diseases: Botrytis blight, damping off, Pythium root and stem rot. 

Pests: none serious.

Wit and Wisdom

  • The genus name, Lobelia, pays tribute to Flemish physician and botanist Matthias de l’Obel (1538–1616), who (with Pierre Pena) in 1570 described a detailed new plant classification system based on leaves. 
  • Do not confuse with L. cardinalis, aka cardinal flower, a native wildflower with a spike form.
  • The species Lobelia erinus is native to southern Africa.
  • Beware: If ingested by humans, lobelia foliage may cause serious health problems. Symptoms of Lobelia poisoning include: nausea, vomiting, diarrhea, salivation, exhaustion and weakness, dilation of pupils, convulsions, and coma.
Flowers
About The Author

Tim Goodwin

Tim Goodwin, the associate editor for The Old Farmer's Almanac, has been reading North America's oldest continuously published periodical since he was a young child, growing up just a short drive from the OFA office. Read More from Tim Goodwin
 

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