How to grow edging lobelia (Lobelia erinus)

Lobelia erinus · garden lobelia, trailing lobelia

Edging lobelia (Lobelia erinus) — low South African plant grown as an annual, 10–30 cm tall, upright for edging or trailing for baskets, covered in small two-lipped flowers in blue, violet, purple, pink or white, often with a white or yellow eye. Edging lobelia grows best in full sun. Water it about every 3 days while it grows.

Updated: October 28, 2026

When to sow edging lobelia?

Sow for seedlings about 9 weeks before planting out.

Plant out in open ground about a week after your last spring frost, once the soil is warm.

It flowers about 70 days after the shoots appear and keeps flowering for about 120 days.

Frost dates · When to plant

Quick facts

Type	Flower
Latin name	Lobelia erinus
Family	Campanulaceae
Also called	garden lobelia, trailing lobelia
Planted as	seed
How it is started	from seedlings
Life span	grown for one season
Planting season	spring
Light	Full sun
Frost	does not tolerate frost
Soil for sowing	from 10 °C
Germination	14 days
Pricking out	21 days after the shoots appear
Seedlings ready	49 days
First flowers	70 days after the shoots appear
Flowering lasts	120 days
Grown in	Open ground, At home

How long does edging lobelia take from sowing to flowering?

From sowing to the first flowers: about 84 days, or 12 weeks.

Step	Day
Sowing	0
Shoots appear	14
Pricking out	35
Seedlings ready to plant out	63
First flowers	84
End of flowering	204

Days count from the day of sowing or planting, by the figures of the card.

Where does edging lobelia grow?

19,941 records of the plant in gardens, fields and the wild worldwide; most photos come from United Kingdom, South Africa, Norway, United States, and New Zealand.

World map: where edging lobelia has been recorded — Darker green means more records. Photos are real observations from those countries — tap one to see it. Map and records: GBIF.org (2026-10-28), © OpenMapTiles © OpenStreetMap. Photo: lisa laws, Алексей Логинов, Håvard Laukeland, Therese Phillips, boytouchgrass, Артем Картушин, jstarspots, Chardonneret (CC BY / CC0).

Edging lobelia, United Kingdom — Darker green means more records. Photos are real observations from those countries — tap one to see it. Map and records: GBIF.org (2026-10-28), © OpenMapTiles © OpenStreetMap. Photo: lisa laws, Алексей Логинов, Håvard Laukeland, Therese Phillips, boytouchgrass, Артем Картушин, jstarspots, Chardonneret (CC BY / CC0).

Edging lobelia care by growth stage

Open ground

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	—	—
Growth	every 3 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 14 days into the stage
Flowering	every 3 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 14 days into the stage; phosphorus and potassium, 28 days into the stage; phosphorus and potassium, 42 days into the stage; phosphorus and potassium, 56 days into the stage; phosphorus and potassium, 70 days into the stage; phosphorus and potassium, 84 days into the stage; phosphorus and potassium, 98 days into the stage

At home

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	—	—
Growth	every 2 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 14 days into the stage
Flowering	every 2 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 14 days into the stage; phosphorus and potassium, 28 days into the stage; phosphorus and potassium, 42 days into the stage; phosphorus and potassium, 56 days into the stage; phosphorus and potassium, 70 days into the stage; phosphorus and potassium, 84 days into the stage; phosphorus and potassium, 98 days into the stage

Growing notes

Light

Full sun or partial shade; where summers are hot, it does best in partial shade.

Soil

Fertile soil rich in organic matter, reliably moist but well-drained; it does not tolerate drought.

Care

Sow indoors at 13–18 °C in late winter, 8–10 weeks before the last frost; it can be tricky from seed, so many gardeners buy plants in cell packs. Plant out after the frosts. Water consistently — it never copes with drying out — and feed every two weeks, with a balanced fertiliser in spring and early summer and a nitrogen-free one from mid-summer. It loves cool weather and often stops flowering in summer heat; then shear it back, feed and water to get a second flush in autumn. Wet conditions bring damping-off, stem and root rot; slugs and snails may graze it.

Other plants of the Campanulaceae family

Edging lobelia belongs to Campanulaceae; 1 other plant of this family has a guide here.

Carpathian bellflowerCampanula carpatica

Plant lists it is in

What to grow on a windowsill or balcony

Part of: Garden flowers · Annual flowers from seed · Long-flowering plants · Flowers to start from seedlings

Sources

Figures checked against these sources.