I was fortunate enough to hear an impromptu talk last week by Begonia guru Margaret Chedra. Begonia are very worthy garden plants for Sydney, especially for shady spots in our gardens. The so-called cane-stemmed Begonia, for example, are summer stars for foliage and flower power and they are at their very best now, though they bloom for up to nine months of the year. These tough heat and drought tolerant plants can form quite substantial shrubs 1-2 m tall, although there are many cultivars that are more compact. They comprise a thicket of slender, upright bamboo-like stems, clothed with lush, lop-eared leaves that are attractive all year round and are ideal for a tropical-style garden.
Some forms have deeply cut palmate foliage but the majority are known as 'angel-wing begonias' because of the unusual shape of their leaves. Foliage colour varies from fresh green through to bronze or blackish-green in some cultivars. Many varieties are beautifully freckled with silver or white spots or splashes, or veined in a contrasting colour. Others have a dramatic contrasting colour on the underside of their foliage. Blooming can begin in November and extend until August in mild climates, and is probably at its peak in late summer and early autumn.
The thick pendulous trusses of long-lasting waxy flowers make the stems arch over attractively. Flowers come in many shades of pink, as well as red, white and orange. Tall favourites include 'Irene Nuss' with lustrous bronze leaves and salmon pink flowers (ht 1.2 m); 'Sophie Cecile' (ht to 1.5 m) with silver splashed, deeply cut foliage which is mahogany beneath, and rose-pink flowers; 'Esther Albertine' (ht 2 m) with pink flowers; 'President Carnot' (ht to 1.5 m), which has green leaves with a burgundy underside and brilliant red blooms, and Begonia undulata (2m; 3m if left unpruned) which has fresh green leaves and crisp white flowers. They make excellent background plants. On a smaller scale, Begonia 'Just Blush' (ht 1 m) has soft pink flowers; Begonia 'White Cascade' (ht 1 m) has dark green foliage with silvery spots and clean white flowers. There are also various hybrids which grow to less than 50 cm in a range of colours, such as 'Fabulous Tom', with orange flowers.
These plants thrive in a part-shaded position with a couple of hours of morning sun, and are wonderful plants for dry spots, even nearby tall trees, as they dislike being over-watered. They can also survive in sunny spots. Interestingly, pink-flowered varieties will be have darker pink blooms in sun than if grown in shade. Their upright form makes them ideal for narrow spaces such as at the side of the house and they are excellent subjects for large pots. Companion plants can include shade-lovers such as Hydrangea, Plectranthus, summer- and autumn-blooming Justicia and Impatiens. Strap-leaved or bold architectural foliage - such as that of Clivia, Philodendron or taro (Alocasia) - can provide contrast of leaf form. Cane-stemmed Begonia with silver spotted leaves look very effective growing with shade-tolerant silver foliage plants such as Plectranthus argentatus or Helichrysum petiolare. Cane-stemmed types can also be under-planted with any of their attractive cousins, the low-growing rhizomatous Begonia, which have stunning patterned and coloured foliage and form an attractive carpet in dry shady areas. Foliage colour varies from fresh green through to bronze or blackish-green in some cultivars. Many varieties are beautifully freckled with silver or white spots or splashes, or veined in a contrasting colour. Others have a dramatic contrasting colour on the underside of their foliage.
Cane-stemmed Begonia are excellent subjects for large pots, especially in cooler areas with frosty winters, which these semi-tropical plants - originally from Brazil - do not like. The pots can be moved into a sheltered position during the winter months. Add perlite to the potting mix used for the pots, to improve drainage. Don't overwater the pots. Larger cane-stemmed plants need a heavy pot so that the plant doesn't topple over.
To prune, old brown canes can be removed at ground level in late winter (at the end of August - a little later in very cold suburbs) and the rest of the canes trimmed at the same time by one-third to a half to make the plant bushier. Newly emerging canes - which resemble bamboo shoots! - should be left unpruned. The plants can be fertilised with a general-purpose food and given a blanket of mulch after they are pruned. Occasionally liquid feeds during the growing season are beneficial. Plants in pots can be given a slow-release fertiliser. They rarely seem to be bothered by pests or diseases. Eventually, old plants may lose their vigour (after about ten years or so) and then should be replaced by a new specimen. To propagate the plants, take tip cuttings containing two nodes in the warmer months. They strike easily from cuttings: the best months to do this are March, April and November. Cut flowers and foliage of the cane Begonia are excellent for use in vases.
There is usually a Begonia Show on in February at Bloomin' Greenery Nursery at Annangrove, NSW. This year, however, it will be held in November. The date will be advised closer to the time.
Blog originally posted on 2 March 2009; updated 21 February 2021.
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