Classification, origin and description
Common name: Columnea.
Etymology: the name recalls the Neapolitan naturalist Fabio Colonna, who lived between the 16th and 17th centuries.
provenance: Central and South America.
Genre description: the genus, which in America constitutes the correspondent of the Asian Aeschynantus, includes about 200 species of suffruticose, perennial, evergreen, often epiphytic plants suitable for greenhouse and apartment cultivation. They have fleshy leaves, with full margins, opposite, of small or medium size, elliptical-lanceolate, sometimes linear and climbing or falling stems, even if they can be erect in the first stage. The flowers, bilabiate with the trilobed and convex upper lip on the back and the linear lower one take on various shades of red-orange and scarlet and bloom, in winter or summer, depending on the species, at the axil of the leaves, following the growth of the drums.
Columnea x lemonei (Berlin Botanical Garden) (photo website)
Species and varieties
Columnea x banksii: hybrid, suffruticose of horticultural origin, it has pendulous stems, which can reach the length of 60-90 cm. The leaves are shiny, dark green in color. From November to April, 6-8 cm long red-orange flowers bloom with lighter spots on the inside of the corolla. Flowering is sometimes followed by the appearance of white berries with violet undertones.
Columnea crassifolia: this suffruticose species, native to the forests of Guatemala and Mexico, has fleshy and semi-erect stems that bear fleshy leaves and red-orange tubular flowers.
Columnea gloriosa: suffruticose species, it is cultivated for the spectacular flowering that lasts from October to April. It has thin and pendulous stems, which can reach the length of 1.5-2 m. The leaves, light green and tomentose, and the flowers, 5-6 cm long, scarlet in color with a yellow spot inside the corolla take hold on them. The "Purpurea" variety owes its name to the leaves, which have showy dark purple shades.
Columnea microphylla: suffruticose species, it has thin stems, up to 2 m long that bear ovate leaves, light green in color and covered with a light purple-colored hair. The flowers bloom from November until April and are 3-5 cm long and bright red-orange in color.
Columnea schiedeana: hanging or climbing species, it has light green leaves and stems, reaching the length of 0.9-1.2 m, with swollen knots. The flowers, up to 5 cm long, scarlet in color with yellow and brown spots, bloom in summer (from May to July).
Columnea x lemonei
Environmental requirements, substrate, fertilizations and special precautions
Temperature: the minimum winter temperature must remain between 10 and 12 ° C, for summer flowering species, and between 14 and 16 ° C, for winter flowering species. From April to October, if the temperature exceeds 20 ° C, the room must be ventilated. The column does not tolerate air currents.
Light: excellent and widespread, away from direct sunlight.
Watering and environmental humidity: the waterings will have to be abundant in summer, reduced in winter (except for the winter flowering species which will have to be watered abundantly in this period). Spring-summer flowering species require a winter semi-rest period. The environmental humidity must be high, especially with high temperatures, also increased by spraying and spraying the foliage.
Substrate: earth-based mixture of leaves and peat, equal parts, with the addition of sand.
Special fertilizations and tricks: administer liquid fertilizer, every 10 days, in the period between May and September. They are repotted every 2 years in June, for winter flowering species; in September or March, for those with spring-summer flowering.
Multiplication and pruning
Multiplication: they multiply using cuttings, taken from March to May, from non-flowering stems. 7-8 cm long, they must be planted in a mixture of peat and sand and in a multiplication box, under glass or plastic cover, taking care to air from time to time to avoid stagnation of humidity, at a temperature of 18-21 ° C. After rooting, they are transplanted into jars filled with the growing substrate. When the plants have taken root well, they will have to be clipped, in order to favor the development of lateral branches. Usually they are placed in suspended baskets. You can also resort to sowing (in February-March) in a mixture of peat and sand. The substrate must be kept slightly damp, in a shady position and at a temperature of 25-27 ° C. Sprouts will appear in three to four weeks.
Pruning: the Columnea needs a cleaning up of the dried buds and the withered flowers. Any bare stems must be cut at the base. After flowering, the branches can be cut up to half, in order to encourage the development of others.
Diseases, pests and adversities
- Aleurotide or white gnat of greenhouses: it weakens the plant by sucking its sap. It can be seen with the naked eye (touching the plant will raise a cloud of midges) and fight with insecticide products.
- Gray mold: it is a mushroom (Botrytis cinerea) which causes the appearance of dark spots and, subsequently, of gray powdery clusters on leaves and flowers. It is facilitated in its spread by very dense plantations and excessive watering. It is necessary to eliminate the affected parts and any "moldy" soil, as well as treat the plant with an anti-cryptogamic product.
- Elongated and thin stems: the plant has little light.
- Falling leaves: temperature too low.