Lobelia

Family Lobeliaceae. Origin - South Africa (Cape Province). Most commonly cultivated.

Perennial herbaceous plant, grown as an annual. Stems thin, strongly branching from the base, densely leafy. Bushes compact, globular, 10-25 cm high. Leaves alternate, small, lanceolate, entire. Flowers up to 2 cm in diameter, two-lipped, on short peduncles, solitary in the axils of the leaves. Color ranges from light blue to deep blue, violet-blue, purple or white, depending on the cultivar. Blooms from June to September. Begins to flower 70-80 days after sowing. The duration and abundance of flowering increase with timely removal of faded stems. Fruits abundantly. The fruit is a many-seeded capsule; seeds are very small (about 50,000 seeds per 1 g) and remain viable for 3 years. In cultivation since 1861.

The main species has three garden forms:

trailing (f. pendula) - with abundantly flowering, drooping shoots 30-35 cm long. Used as an ampelous plant, excellent in hanging pots;

upright (f. erecta) - bush columnar in shape up to 25 cm high;

compact (f. compacta) - bush dense, rounded in shape, 10-15 cm high.

Among cultivars in the Compacta group, attention should be paid to 'Half Moon' (corollas blue with a clearly defined white eye in the center; early flowering), 'Kaiser Wilhelm' (flowers bright blue, similar to gentians), 'Riviera Lilac' (a new variety with lilac-pink flowers), and 'Riviera Sky Blue' (plants tall, suitable for container planting; flowers sky-blue). Among the trailing cultivars notable are 'Reggata Rose' (bushes very compact, flowers raspberry-pink) and 'Reggata Sky Blue' (differs from the previous only by sky-blue flowers).

Site conditions: in its native South Africa, perennial lobelias grow along river banks or under the shade of shrubs, where the soil dries quickly. In temperate countries, especially in northern latitudes, they are cultivated almost exclusively as seasonal annuals. Young plants are planted outdoors after the last spring frosts have passed. Although well-hardened seedlings can withstand frosts down to −1 to −2 °C. They require bright sunlight and constant moisture, since even brief drying of the roots prevents the plants from restoring their original form.

Soil: Lobelia grows well on loose, loamy or sandy-loam soils. The soil should be well-drained so that water does not stagnate in it, and not too fertile. With an excess of nutrients in the soil, lobelias develop mainly leaves and stems at the expense of buds and flowers.

Care: for lush and long-lasting flowering it needs periodic fertilization and abundant watering in dry weather. On soils that are too rich in organic matter, lobelia becomes leggy, produces a mass of leaves and flowers poorly. After the first wave of flowering the plants are cut back to a height of 5 cm. After that they produce shoots again and a second wave of flowering occurs. When caring for lobelia, attention should be paid to watering: if the root ball dries out, its stems bend. Diseases and pests have not been identified.

Propagation: by seedling method. Seeds are sown indoors at an air temperature slightly above 20°C in the period from February to April. They are very small and require bright light for germination, so they are not covered with soil. The substrate must be kept constantly moist. Shoots appear uniformly 10-15 days after sowing. When the seedlings emerge, the temperature is reduced to 10-15°C. The seedlings are so tiny that they should not be pricked out earlier than a month after emergence and several plants are moved together. After 12-15 days the seedlings are fed with a complete fertilizer. Transplant outdoors from mid-May at a distance of 10-15 cm from each other. When the plants reach 2.5 cm in height, the tops can be pinched for better bushiness.

Some cultivars when sown from seed do not retain desired traits, producing segregation. They are propagated vegetatively, primarily by stem cuttings.

Uses: Lobelias of the 'Compacta' series are excellent for flowerbed arrangements, containers and the edges of flower beds and borders. They can also be placed in the center of a hanging basket. Plants from the 'Pendula' series have stems that arch and naturally hang over the edges of window boxes, pots and hanging baskets, draping their sides with green foliage and numerous small flowers that may be blue, pink or white. Trailing lobelias can be planted both in beds and borders, using them as groundcover plants.

Companions: Lobelia pairs well with red pelargoniums, scarlet salvia, and yellow Mimulus. It looks best in close proximity.