Lobelia valida L. Bolus
Common names: limestone lobelia, galjoen flower (Eng.); galjoenblom (Afr.)
True blue flowers are always special. Worldwide they are sought after, a rare colour to find in a flower. The colour is striking by itself, breathtaking in mass and always a wonderful contrast to most other colours.
Branching from the base, the long branches stand proud with their blue flowers densely packed at the top of the stems. The plants grow to about 40 to 60 cm. in height. The light green leaves, scattered along the branches, are flat and soft with coarsely toothed edges.
Lobelia valida has deep blue flowers throughout summer. It is a superb perennial for the garden. The blue flowers, crowded at the tops of the branches, are typical of lobelia. Looking closely, one will see the flowers are two-lipped. The upper lip has two small petals split to the base at the back, and the lower lip has three larger petals. The lower petals are marked with white and a blotch of bright yellow at the centre, clearly guiding the nectar-feeding fly, which pollinates the flowers. These long tongued flies are specially adapted with long sucking mouthparts to collect nectar hidden at the base of a deep tube.
Lobelia valida is assessed as Vulnerable (VU) on the Red List of South African Plants. Its wild population is declining and it is known from fewer than 10 sites which are threatened by alien plant invasion and coastal development.
Distribution and habitat
Lobelia valida grows on limestone hills and coastal dunes from Bredasdorp to Riversdale in the Southern Cape.
Derivation of name and historical aspects
In its natural habitat the local people maintain that the flowering time coincides with the galjoen fishing season (Nov to April), hence the common name, Galjoenblom.
The best time to find this lobelia in the wild is after fires when they flower most conspicuously.
The lower petals are marked with white and a blotch of bright yellow at the centre, clearly guiding the nectar-feeding fly, which pollinates the flowers. These long tongued flies are specially adapted with long sucking mouthparts to collect nectar hidden at the base of a deep tube.
Growing Lobelia valida
Lobelia valida grows easily in the garden given a sunny position with light well- drained soil, enriched with compost. It is ideal for coastal gardens. Flowering abundantly throughout summer it is best to replace plants regularly, as the stems tend to get untidy and woody at the base after a year's vigorous growth. Plants live for about 3-4 years, but one might wish to replace them sooner in the garden. For the best display, the plants should be planted 15cm apart. Lobelia also looks beautiful mixed with other summer flowering perennials such as Pelargonium peltatum ( Ivy leaf pelargonium), Geranium incanum (carpet geranium) and Diascia integerrima.
Lobelia valida can be propagated by seed or cuttings. The plants set seed freely, producing small little black seeds. The seed can be sown any time of the year into seedtrays filled with a well-drained medium. Sow the seeds thinly as the germination is usually good and cover lightly with sifted soil or white sand. Place the trays in the shade and keep moist. Germination takes about a month, with the young seedlings grow very slowly in the beginning. Prick out the seedlings as soon as they are large enough to handle and grown on in bags until they are big and strong before planting out into the garden.
Strong tip cuttings are best taken in spring ans summer when they are less inclined to rot. The young plants respond well to fertilizer feeding and by pinching the tips, the plants are encouraged to grow bushier. Lobelia valida prefers a slightly alkaline soil.
Liesl van der Walt
Kirstenbosch National Botanical Garden
conservation information updated August 2016
Plant Type: Perennial
SA Distribution: Western Cape
Soil type: Sandy, Loam
Flowering season: Early Summer, Late Summer
PH: Alkaline, Neutral
Flower colour: Blue
Aspect: Full Sun, Afternoon Sun (Semi Shade)
Gardening skill: Average