5-10 deg C/41-50 deg F
This is an important family for house-plants; there are numerous very beautiful species forand foliage. They have widespread origins throughout the sub-tropics and tropics. The tuberous make splendid pot plants for the summer and autumn months, bearing large, showy and handsome foliage. There are also types with smaller and more pendent or tassel-like flowers, which are excellent for hanging or baskets. All these tuberous kinds have been derived from several species and were introduced by James Veitch and Sons from 1865 to 1868. but have now been greatly developed.
Named cultivars of giant double-flowered begonias can be bought from specialists, but are expensive and better suited for exhibitions or for growing in greenhouses or conservatories. For the home, it is better to buy tubers offered by well-known nurserymen. Start the tubers into growth from February onwards. by immersing them in a pan of moist peat placed on a warm window-sill. As soon as the shoots appear, pot them into any good.
setting one tuber to each pot. Large-flowered begonias need at least 13cm (5in) pots. The same applies to multi-flowered sorts that produce a large number of smaller blooms. The pendulous kinds are best grouped three or more in larger pots or baskets and planted near the edge, so that thecan hang over. Set them so that the top of the tuber is level with the ’s surface. If there is any doubt, the concave side of the tuber should face upwards. The large-flowered begonias will need a cane for support as they grow, and it is best to remove the female flower buds -which have winged capsules attached – as soon as they can be picked off without damage. This allows the large, showy male flowers to develop fully. Keep the plants in good light, but not in a window receiving direct sunlight, which will scorch the foliage and bleach the blooms. At the end of the year, reduce the amount of water given and let the soil become dry. Place the dry pots in a frost-free place or remove the tubers and store them in clean, dry sand during winter. The tubers can then be repotted when it is time to start them into growth. The evergreen begonias, which have fibrous or rhizome-like , are prized for their very beautiful foliage which has attractive flowers too, but these generally take second place. A species that deserves to be grown more extensively is B. corallina, together with its hybrids such as ‘Lucerna’. This has impressive silver-spotted foliage, purple-red below. and bears enormous clusters of glorious pink flowers from summer to autumn. If allowed, the plant will reach more than 90cm (3ft) in height, but small plants also flower well. It will survive very cool rooms in winter, but may then deteriorate. New growth quickly resumes in spring.
A great favourite is B. rex with arrow-shaped foliage of various tints marked with silver. It makes a neat pot plant. There are numerous named hybrids with different colouring. Similar in habit and very striking is B. masoniana, popularly called the iron-crossbecause of a very bold chocolate-brown marking on each . Also popular are B. metallica, so-called because of the metallic sheen of its , which have purplish veins too, and B. boweri. The latter has the common name eyelash begonia, since its leaves have a border of long lash-like hairs and are prettily coloured with brownish streaks. It bears pinkish flowers in spring. B. manicata shows its pink flowers during winter and again has charming foliage having red hairs below and a reddish border. B. coccinea is similar to B. corallina and is
usually seen as the hybrid ‘President Carnot’. B. scharffii (syn. B. laageana), elephant’s ear, has dark green hairy leaves tinted red below, and attractive pale pink flowers.
Fibrous-rooted cultivars of B, semper-jlorens and various hybrids, extensively used for garden bedding, make splendid houseplants. Sometimes, they can be lifted and potted in autumn, but it is better to start from seed sown in early summer. Given a bright window-sill, the plants will often flower during winter. Their foliage is pleasing, being glossy and often having dark, bronzy or reddish tints, against which the flowers show up particularly well. The habit is very neat and compact, and 10cm (4in) pots are adequate. Some recommended cultivars are ‘Muse’ (large-flowered). ‘Colour Queen’ (with cream-variegated foliage), and ‘Devon Gems’ (mixed coloured foliage), easy vigorous growth, and very free-flowering.
The Flatior hybrids produce small clusters of long-lasting flowers, and these make very good houseplants. ‘Elfe’ is a delicate pink with deeper shading. ‘Nixie’ a deep red. ‘Ballerina’ has slightly larger flowers of a lovely orange, while ‘Balalaika’ is an attractive yellow. Quite new is ‘Emerald Isle’, a houseplant to grow from seed on a window-sill. It forms a neat group of shiny, oval leaves with pointed tips borne on short, strong stems, and has pale pink flowers. All the foliage begonias do best in winter if the temperature is not allowed to fall below about 10 deg C (50 deg F). as then they are liable to lose their foliage, or it may turn brownish. In summer,can be generous and spraying the foliage with a mist of water from time to time will encourage new growth. Any or division of for should be done in spring. Many of the foliage begonias can be propagated from leaf . Although most of the types used as houseplants will tolerate fair shade, they usually only develop the best leaf colours in good light. However, this does not mean exposure to direct sunlight, which could scorch and bleach the leaves. Fibrous begonias of the B. semperflorens type are exceptions in that they will often withstand even direct sunlight on a window-sill. These certainly need all the winter sun they can get to encourage winter flowers and good foliage colour.
Generally, begonias are remarkably free from pest or disease troubles. Yellowing of foliage is generally due to overwater-ing or letting the plants go dry. Low temperatures will cause this too, as well as leaf drop.