Lobelia erinus

Growing in Pots, Balconies & Indoors

Trailing lobelia smothers itself in tiny blue, violet or white flowers and is a classic for baskets and window boxes. The grower rates it for containers but not indoors – it needs good outdoor light to flower non-stop.

Quick Details

• Container Size: A basket, window box or trough – superb spilling over the edge
• Indoor Suitability: Not a houseplant (grower); a sun-loving trailer for outdoor baskets and boxes
• Best Spot: Full sun to partial shade; a bright spot with some direct sun is ideal.
• Soil & Drainage: Aerated, organic-rich mix (quality potting mix, or peat/coir with perlite or vermiculite); it must drain freely.
• Watering in Pots: Keep the mix evenly moist, letting the surface dry slightly between waterings; pots dry faster than open ground.

Indoors & On the Windowsill

• Not a houseplant: The grower marks it unsuitable indoors; in weak room light it stretches and stops flowering. It is bred for outdoor baskets and edging.
• Season only: Usually grown as an annual – resow or replant each season rather than overwintering.

On a Balcony or Patio

• Light & exposure: Full sun to part shade suits it; in very hot climates a little afternoon shade keeps it flowering longer. Cascading stems look wonderful from railings and hanging baskets.
• Watering: Keep the mix evenly moist – baskets dry quickly in wind and reflected heat, and lobelia sulks if it dries out.

Choosing the Pot, Soil & Long-Term Care

• Pot & drainage: A basket, box or pot with free drainage; keep the shallow mix from drying out.
• Potting mix: Use a well-aerated, organic-rich mix – quality potting mix, or peat/coir blended with perlite or vermiculite.
• Feeding: Baskets leach fast – feed regularly with a dilute balanced fertiliser for continuous bloom.
• Repotting: Grown as an annual; start with fresh mix each planting.

Bloom & Flower Guide

Quick Details

• Bloom Season: Spring through autumn
• Flower Appearance: Tiny two-lipped flowers that resemble a little winged insect
• Edibility: Not edible — grown purely as an ornamental; all parts are toxic if eaten

Detailed Blooming Overview

Trailing lobelia smothers itself in small, jewel-toned flowers from spring through autumn, making it a favourite for edging, baskets, and tumbling over walls. The flowers draw in pollinators and keep coming through the season with light care.

Flower Characteristics

• Colours include blue, purple, white, and pink.
• Each flower has one petal split into lobes — three below and two above — giving it the look of a tiny flying insect.

Bloom Care & Thinning

• Encouraging bloom: Trimming spent flowers and leggy growth refreshes the plant and keeps it flowering.
• Safety: Lobelia erinus is toxic if ingested — keep it away from children and pets and treat it strictly as an ornamental.
• Light and water: Full sun to half shade with even, average watering suits flowering.