Garden and Flowers

GARDEN LOBELIA

The ancestor of our garden lobelias was a South African plant about 10 in tall, but nurserymen nowadays would be mortified if their labours produced a plant that high. In fact, this rarely happens, since lobelias grown for gardens are very compact or have a trailing habit. The first group is referred to as compacta or ‘Compacta,’ but more precisely as the Lobelia erinus Compacta Group. The plants have a compact upright habit and form green tufts 4-6 in high. They are highly suitable for flower-beds, containers, and edging purposes, but may also be planted in the center of a hanging basket.

The second group, Lobelia erinus Pendula Group, often referred to as pendula or ‘Pen-dulas,’ ultimately acquire a trailing habit. As young plants, trailing and upright lobelias are almost indistinguishable from one another. It is not until they start growing vigorously that trailing lobelias reveal their true nature by arching over the rims of window-boxes, pots, and hanging baskets and concealing them with a mass of green-leafed stems and numerous small flowers, usually colored blue, pink, or white.

Trailing lobelias are, in fact, also suitable for flower-beds and borders, where they will cover the soil with their creeping stems. Large quantities of both groups of plants are always on sale in May and June, having been grown on, usually from seed, in large greenhouse complexes during the preceding two or three months.

Several cultivars that do not remain true to type when grown from seed are propagated by cuttings. In South Africa, lobelias are perennials growing along watercourses and in the shade of bushes where the soil dries up less quickly. In our part of the world, the plant is susceptible to frost and is therefore cultivated as an annual. Put bought plants in a very light and preferably sunny spot out-of-doors after the last night frost. Make sure the soil does not dry out, because lobelias do not recover well from lack of moisture, however temporary the condition may be. Also make sure the soil is well drained, and do not add much fertilizer. Excessive feeding stimulates leaf formation at the expense of flowers. The flowering season may last from May until September.

Few people sow lobelias themselves, but here are a few tips for those who like a challenge. Sow indoors from February to April at a temperature of just over 68 °F. The very fine seed should not be covered, because it can germinate only in light conditions. It must not dry out either. The seedlings grow on well at 50-59 °F. After hardening off in April-May, they may be planted out-of-doors after the last night frost.
Cultivars belonging to the Compacta Group include Lobelia erinus ‘Half Moon’ (blue with a definite white center, early flowering); Lobelia erinus ‘Kaiser Wilhelm’ (gentian-blue flowers); Lobelia erinus ‘Riviera Lilac’ (a lilac-pink newcomer); and Lobelia erinus ‘Riviera Sky Blue’ Improved, a somewhat taller gentian-blue plant, very suitable for containers.

The trailing lobelias include: Lobelia erinus ‘Regatta Rose,’ an initially very compact cultivar with crimson-pink flowers; and Lobelia erinus ‘Regatta Sky Blue,’ comparable to the previous plant, but bearing sky-blue flowers.