Begonia is succulent flowering perennials belonging to the largest flowering plant genus of the Begoniaceae family, consisting of more than 2,000 diverse species. These plants are indigenous to humid subtropical and tropical environments of Asia, Africa, and South America.
Some species are popularly cultivated indoors as ornamental plants in temperate climates, with some species cultivated outdoors in summer for their colorful flowers.
These plants are terrestrial (some epiphytic) herbs or shrubs and are usually classified as fibrous, rhizomatous, or tuberous.
These plants are monoecious dicots, producing male and female blooms, with the male flowers containing several stamens while the female flowers have large inferior ovaries and 2 to 4 stigmas. Most species produce fruits in winged capsules that contain several tiny seeds, although some produce baccate fruits. The asymmetric leaves are often variegated or marked.
Many begonias produce flowers throughout the year except tuberous begonias, who go through a dormant period. Tubers should be stored in cool, dry places during dormancy. Attractive wax begonias are often cultivated outdoors as bedding plants and can adapt to growing indoors during winter, living for 4-5 years.
A group of hybrids with larger leaves and flowers were derived recently and sold as “Dragonwing” begonias. Tuberous begonias are often cultivated in containers. While most Begonia varieties originate from tropical or subtropical climates, one species, Begonia grandis, originates from China and can tolerate low temperatures of 0 to -10°F and is popularly called the “hardy begonia”.
Culturally, these plants denote caution, consideration, and good communication between people. They are commonly given as gifts to repay favors – these meanings/interpretations are largely associated with Michel Bégon, a French politician and diplomat in the 1600’s. The plant was named in honor of him by Charles Plumier, a noted French botanist.
These begonias grow from tubers and are popular flower bed plants due to the rapid growth of their attractive blooms. Their heights range from a few inches to more than a foot, and flowers in single or double blooms—some reaching 6 inches in width.
Although some varieties do flower, most varieties are better known for their striking foliage rather than flowers. These begonias are characterized by their roots that resemble knotty, horizontal stems that spread along with the soil. These types of begonia have colorful leaves, varying from white and yellow to purple, red, and green, often with striking patterns and combinations.
These begonias have roots like most plants that grow down into the soil. They are attractive flowering plants and also have a wide variety of colors and are cultivated in flower beds or containers, their long stems and flowers look very attractive when grown in window boxes and hanging baskets.
Begonias mostly grow as understory plants in forests and need bright shade. Just a handful tolerate full sun, especially in warmer climates. They need light to maintain their coloring, but indirect bright light works best for most varieties. Avoid growing them in direct sunlight.
In dense shade, however, fibrous and tuberous begonias will develop more leaves than flowers, while rhizomatous begonias will flourish as they are mainly grown for their foliage.
Water these plants only when the topsoil becomes dry. Ideally, the soil must be kept slightly moist, but not too saturated because they are very intolerant of over-watering and easily develop root rot or leaf drop. Watering can be reduced in winter.
Achieving the right balance caring for begonias with watering is a big challenge – a good practice is to wait for the leaves to slightly wilt, indicating that the plant needs water. Always keep the leaves dry when watering.
These plants do need high humidity levels of 50% or higher. Misting the leaves could lead to leaf spots. It would be advisable to use a humidifier, particularly in winter, to maintain proper humidity. Growing plants closer to each other will also help since they will increase humidity levels.
The various begonia species have diverse temperature requirements, but since almost all species originate from the tropics, they more or less require warm temperatures.
They are intolerant of temperature fluctuations and, except Begonia grandis, will not tolerate low temperatures below 60°F. Tuberous begonias can be kept in dry conditions over winter.
Generally, begonias need well-drained soil that is not consistently wet yet not completely dry. The soil can be amended with organic compost or moss to provide nutrients. Potted plants should have several drainage holes.
They don’t like damp soil that can make their roots rot. They need just enough watering to lightly moisten the soil but not saturate it.
Repotting begonias every year will help ensure that they have fresh well-drained soil to grow in, although they prefer to get a little pot bound. Larger plants can be pruned and cut down instead of repotting.
Almost all begonias are propagated from stem cuttings or division, you can use the leaf-cutting method for rhizomatous varieties.
Propagating from stem cuttings is simple – take a 4-inch long stem cutting and insert it directly into moist soil. Water as recommended and provide it with indirect bright light.
Fibrous begonias are perhaps the easiest of the three types of begonia to propagate from cuttings, but you can also succeed in rooting cuttings with most of the other two types of begonias.
Propagating by division involves splitting the plant (better when repotting) into several sections, each having stems and roots. Insert each section into well-drained soil and care for them as usual.
You can feed begonias monthly with 10-10-10 liquid fertilizer – equal parts of phosphorus, nitrogen, and potassium every 3 to 4 weeks diluted in a ratio of 3:1 water and fertilizer, too much feeding will result in an untidy plant, so monitor and adjust the fertilizer to suit the variety of begonia. Do not feed the plant in winter.
Begonias respond well to fertilizer being poured around the base of the plants rather than foliar sprays as the stems and leaves of some varieties can be damaged with direct contact with fertilizer sprays.
Pruning is only necessary to control unruly stems to maintain the plant – these can be used to propagate new plants. Remove dead or yellowed leaves and spent flowers/stalks.
Bacterial leaf spot, botrytis blight, and mildew could occur if the leaves are wet for extended periods. Remove affected leaves and stems immediately. Root rot can also be a problem with over-saturated soil. Begonias should be grown in well-draining soil and water properly to avoid these problems.
Aphids, mealybugs, and caterpillars can also infect these plants. Generally, repeated applications of a neem oil spray will deal with these pests.