Non-tuberous Begonias

All non-tuberous begonias are frost-tender. For optimal growth, temperatures between 54°F (12°C) and 76°F (24°C) are required. Although they like good ventilation (which helps prevent mildew), they do not like cold winds. Fortunately, there are many that grow well indoors and some that are suited to container culture only, so even growers in cooler areas can enjoy these plants year-round as houseplants, and in conservatories or terrariums.

Wherever they are grown, good light is essential. Morning and afternoon sun will help give good foliage color, prevent legginess, and improve the quality and quantity of the flowers. For best results avoid dark corners.

Humid conditions of around 40-60 percent are ideal. In the house as container plants, the humidity can be increased by setting the container over, but not in, water, e.g., by placing the pot on some pebbles in a saucer. This is particularly useful in the winter if the heating system is drying out the atmosphere.

All begonias prefer free-draining soil and, if grown in containers, a free-draining open mix. Beware of over-watering container-grown plants. Water should be given only when the mix is dry to the touch, but then it is important to add enough water to thoroughly moisten the mix. Care should be taken, however, to avoid watering the leaves.

Every few weeks during the growing season, a weak liquid fertilizer may be applied, but only when the mix is damp, or the roots will burn. Such applications should cease during the dormant period (winter).

Pinching out improves branching and bushiness, and pruning improves the shape. Damaged or aging leaves and spent flowers should be removed.

In general, these plants are remarkably free of disease. Attention to the above requirements will go a long way toward preventing mildew, the main problem that can occur.

Non-tuberous begonias by type

All begonias, mentioned below, are suitable for container culture and may be grown as houseplants.

Cane-like

Today, over 200 species and cultivars are known in this group, so named because of their stiff cane-like stems. Many of the Cane-like species grown, nowa-days originated in Brazil, with most of the plants in this group having been discovered in the 19th century. They are deservedly popular for their graceful, pendulous clusters of flowers, which last for long periods in the warmer areas, and range in flower color from white through pink to salmon-orange. The leaves, which vary considerably in shape, often have attractive silver or white dots and markings.
Plants can vary in size from a mere 12 in (30 cm) tall to in excess of 15 ft (4.6 m) high when grown outdoors in warmer climates. The Superba types are the tallest growing and generally have spotted leaves, while the Mallet types are squatter, not growing much above 24 in (60 cm). These mostly have lovely mahogany-red foliage covered in red hairs. In addition, there are many other types generally grouped under the description of low-, medium- and tall- growing. A number are popularly known as "Angel Wing" begonias, and others as "Tree" begonias.
Canes do well in both containers and open ground but, as these plants are deep-rooted, containers should be large enough to accommodate a fairly large root system. Repotting from time to time is desirable, particularly in spring.
Propagation by cuttings is relatively easy, and the best results will be achieved using tip cuttings taken from growing shoots. These should be cut to a length that includes three nodes, cutting just below the lower node. Leaves are stripped from the bottom of the stem, leaving only two or three, and the lower portion of the stem is inserted into the rooting medium. Roots will appear in three to four weeks. Leaf cuttings are not recommended.

Shrub-like

The second largest begonia group is the Shrub-like, which now numbers about 300 species and hybrids. Apart from a small number that have their origin in Asia and Africa, Central and South America were the source. As early as 1688 in Jamaica, the physician and naturalist Hans Sloane discovered Begonia acutifolia, which is still grown today.
Plants in this group have woody stems and excellent foliage, which ranges from being extremely hairy to totally bare. Leaves are quite varied in shape, size, and texture. The plants flower really well if a good general fertilizer is applied regularly. Flower colors are generally in the range of white, cream or pink, although a few are available in other shades such as yellow and salmon. As their name would suggest, they tend to be bushy plants, producing shoots at the base. They often have dense growth and make good container specimens.
When grown outdoors, the bare-leaved varieties are able to tolerate more direct sunlight than their hairy counterparts, due to the reflective nature of the leaf surface.
The preferred method of propagation is by taking cuttings, using the tips removed when pruning. The shoots are cut 2-3 in (5-7 cm), leaving two or three leaves, and the lower half of the stem is inserted into the rooting medium. Roots will appear in three to four weeks.

Thick-stemmed

This is a relatively small group of 70 or so different species and hybrids not widely known or popular, being grown by collectors mainly for their curiosity value. As their name would suggest, they have thick stems from base to tip. They do make good container plants, but are fussy about good light. Some varieties can grow to 6 ft (1.8 m) in height even in containers. Therefore, care is needed when selecting which ones to grow. Almost all have large- to medium-sized leaves.
When propagating, the best results are obtained from leaf cuttings because of the thickness of the stems and the position of the leaves at the extremities of these.

Trailing-scandents

Although there is not a wide selection in this group, they are well worth growing, particularly the fragrant types. Most of them originate from South America. The stems are long, and the leaves small. Some of the newer hybrids have attractively marked and colored leaves. They bloom in various seasons, and most have clusters of flowers. The Trailing scandents often make good hanging basket plants, while others can be trained as climbers in and around the garden, depending on climatic conditions. They also make good houseplants. These begonias propagate very easily from tip and stem cuttings taken during pruning. Treat the cuttings as for Shrub-like.

Rhizomatous

Many hundreds of species and hybrids make this by far the largest group, Rhizomatous begonias, are grown mainly for their attractive leaves and foliage. Mexico is the source of most, and quite a number of the early discoveries (before 1850) are still popular today, together with the many hybrids that have been developed.
Leaf colors, textures, patterns and size are highly varied, which is why they are so popular as houseplants. However, some varieties grow quite large, with leaves exceeding 18 in (45 cm), so are suitable only for the outdoors. Most of the flowers are insignificant and grow on long stems above the plant foliage. However, these can add to the beauty of the whole plant, especially as most flower in late winter and early spring when other plants are less obliging.
The characteristic rhizome of the species is a procumbent or subterranean, root like stem, which produces roots from its lower surface and leaves and shoots from the upper. The group is subdivided into those with erect and those with creeping rhizomes, the latter type tending to look both bushy and compact.
Over-watering these plants, especially during the winter months, tends to produce rot in the rhizome. The group prefers humidity at the higher end of the recommended scale for begonias (60-70 percent). A small amount of fertilizer can be given during active growth. Repotting is advisable only in the springtime.

Rex Cultorum

In the 19th century, B. rex plants, grown solely for their foliage, were very highly sought after and were hybridized in the hundreds. Today's hybrids contain the genes of as many as 15 other species of begonias and the group, now consisting solely of hybrids, is known as Rex Cultorum. In the main, Rex Cultorum are rhizomatous, although some that were developed by crosses with tuberous and semi-tuberous begonias are not strictly so.
Because today's hybrids come from such a broad breeding spectrum, they are highly varied. These plants are grown solely for their foliage, which is truly magnificent. The colors of the leaves can range through green, red, pink and lavender to silver and even black. Although leaf size and growth habit is so diverse, they can be easily identified as a Rex by their distinctive leaf shape.
Rex begonias enjoy slightly warmer conditions, around 75°F (24°C); they do not like hot temperatures, but will survive down to 50°F (10°C) or lower, as long as they are not frosted. Their main love is humidity-generally around 60 percent is ideal, but some varieties like it even higher. They also prefer high light levels but not direct sunlight. Good ventilation is essential to prevent attacks of mildew, and care when watering, to avoid wetting the leaves, will also help.
These plants do have a dormant period over the cooler winter months, when they prefer to be kept on the dry side and not given any supplementary food, but even at this time the humidity must be maintained. In the spring, plants should be repotted into a free-draining open mix; some coarse grit or charcoal added to the mix will be helpful. Do not compress the mix with the fingers when repotting, but leave it light and fluffy.
In spring, biweekly feeds of a 20-20-20 NPK fertilizer at half strength may be given, but high nitrogen fertilizers should be avoided so the plant stays tight and compact. As the summer progresses, the feeding should be reduced.
Pruning in the winter will keep the plants tidy. If the rhizome becomes dry and gnarled, it is best to replace the plant with one that is younger and more vigorous.
Plants can be propagated very easily by leaf cut- tings or by stem cuttings from sections of the rhizome. Most growers prefer the leaf cutting, which, although somewhat slower, produces new plants in larger numbers.
Various methods can be used for taking the leaf cuttings:

• Cut a leaf, shorten the stem, and insert it into a small container of sand, pumice or other propagating mix.
• Nick the veins on the underside of a leaf, lay it on damp sand, and weight it down with pebbles to ensure the cuts contact the sand.
• Cut a leaf in "V" sections from the stem to the outer edge and insert these wedges into the propagating mix. In all cases, rooting should take three to four weeks.

Semperflorens (Wax or Bedding begonias)

This group is the most widely known of all begonia types. As well as being popular with the home gardener, they make a wonderful mass display in public gardens and parks. The term Semperflorens aptly means "ever-flowering". Following the original crosses in 1878, hybridizing continued over many years to produce the Semperflorens varieties of today. The name Semperflorens Cultorum was adopted in 1945 for this group.
There are still a number of Semperflorens species obtainable, but, although some are dwarfish, most tend to be taller than the modern hybrids, growing up to 2 ft (60 cm) in some cases. These are grown mainly by people who specialize in original plants.
Semperflorens now come in a range of colors-catalog examples include white, clear pink, rose, white with margin (rose, scarlet, and salmon-red), salmon or salmon-orange. All have attractive foliage, with green, variegated or bronze available. A recent introduction has been a double-flowered variety in pink, red or white. The Semperflorens hybrids generally grow to about 8 in (20 cm), allowing them to be effective as border plants.
As well as being grown en masse, Semperflorens make excellent container plants, either as a border around a large container or even inserted into sphagnum moss around the sides of hanging baskets, where they make an attractive display. They are equally as good in individual containers. So versatile are they, their use is only restricted by the whim of the grower.
Semperflorens must be grown in good light or they will become leggy. They are relatively tolerant of heat, so can be grown in full sun, although it is preferable to accustom them gradually to these conditions.
If planted in groups, a spacing of 8 in (20 cm) is required to allow the plants to spread. Semperflorens are bushy by nature, but pinching out the growing tips of the stems and the buds as they appear will significantly improve the quality of the blooms on each plant and will ensure that it will be very bushy and floriferous. This may be done up to three times, two weeks apart.
Semperflorens are fibrous-rooted, so in the main are treated as annual plants. However, in warmer climates, where there are no frosts, they can be cut back by about two-thirds if they become too tailor leggy, and they will grow again in a very short time. Even in areas where frosts may occur, if grown in the garden, they can be covered with straw, which will give them protection, allowing them to regenerate again in the spring. If they have been grown in containers, they should be moved into shelter for the winter when frosts are anticipated, that is, when the temperature is forecast to drop to 24°F (5°C) and the weather is clear. If a heated greenhouse is available, the plants can be moved there for the winter months, thus ensuring continuous color.
Semperflorens grown in containers in a good potting mix to which sufficient controlled- release fertilizer has been added should require no further fertilizing; likewise in the garden bed, provided it has been well prepared and fertilized. If supplements are considered necessary, a weak dose of fertilizer with a high potassium content may be applied every three weeks.
As a group, they are susceptible to fungal diseases such as mildew and botrytis. A spraying program may be adopted to overcome this problem, particularly where there is a big variation between the day- and night-time temperatures. To further reduce the incidence of these diseases, refrain from overhead watering, which wets the foliage. A trickle or ground-soaking water system is recommended, as this keeps the root structure damp and cool and reduces the danger of fungal problems.
Propagation of the modern hybrid types is done mainly from seed, since they are so easy to grow. Cuttings may also be taken, or, when the plant is of a sufficient size, it may be divided using a sharp spade or knife. With the natural species, plant propagation is from cuttings, either by removing the tips or by taking basal shoots from around the base, with the best results achieved from basal cuttings.

Comments