Lobelia erinus is a classic summer plant, the star of many traditional bedding displays, and in window boxes, hanging baskets and pots, often combined with pure white Alyssum. Flowers in shades of blue, red, violet, white or purple, sometimes with a white eye, on delicate green or bronze foliage, make it a perfect foil for larger flowered annuals, such as petunias or salvias.
A favourite of parks departments' mass carpet bedding schemes in the past, it is more usually seen in part of mixed arrangements in modern gardens. It is a low growing, bushy or half hardy trailing perennial which is usually grown as a half-hardy annual. Read more
How to grow Lobelia
Sow indoors from January-March, thinly, in trays of good-quality seed compost, gently pressing the seeds into the surface. Lobelia needs light to germinate, so don’t cover the fine seeds with soil. Keep the soil damp by using a fine hand sprayer. Germination takes between 7-14 days.
Maintain a temperature of 15-20°C/60-68°F in a propagator. After germination, thin out into clumps when large enough to handle to 2.5cm/1in apart. Harden plants off and plant out from late May after the last frost.
The key to getting the rounded dense clumps packed with flowers is to plant Lobelia in clumps, not singly, unlike most other annuals. Space clumps of plants 10-15cm/4-6in apart and they will knit together to form a continuous mat of colour.
Lobelia likes moist, but well-drained soil or potting compost in a sunny site. Without enough light, plants will struggle and produce fewer flowers. Hanging baskets dry out very quickly in dry weather and require daily watering to keep plants blooming.
Feed with a high-potassium fertiliser (a tomato fertiliser is ideal) every 14 days until the end of September to ensure plants flower until the first frosts.
Did You Know?
The dwarf bedding strains of Lobelia (L. erinus) have been cultivated since the seventeenth century. It is native to Southern Africa, where plants can be found mostly on lower mountain slopes and coastal flats. It can be seen in the wild from the Bokkeveld Mountains to tropical Africa. Show less