How to Grow and Care for Begonias

Begonias are fairly low maintenance and can provide long periods of bloom. Some varieties have less showy flowers but are prized for their attractive foliage. In summer they can bloom for weeks at a time, from summer through late autumn. When kept indoors, they're capable of blooming non-stop, depending on variety. Tuberous begonias do go through a period of dormancy when flowers and foliage die back for a few weeks. But other types of begonia can bloom constantly all year long. Be sure you're following care instructions for the specific type of begonia you have.

In cooler climates, these tropical plants are mainly grown as indoor houseplants or as annuals outdoors in summer. With their richly-colored blooms and foliage, they're commonly used by landscapers in outdoor container arrangements.

How to Care for Begonias

Begonias are generally not difficult to grow or maintain, but it's important to know what type you have so you can care for it properly. In general, begonias like indirect sunlight or shade, regular watering, and well-drained soil that is rich in organic matter. They need regular deadheading to clear away spent flowers.

Light

Tuberous begonias in containers need a bit of sun but partial sun is fine. Indoors, begonias do best in indirect light. Fibrous or wax begonias planted in the garden will flower consistently in shade or partial shade. Too much bright sun might wilt the delicate petals or cause the colors to fade.

Soil

Begonias enjoy a porous, rich soil that is slightly acidic. Peat-based soils with plenty of organic matter including leaf mold are good for begonias. Good drainage is essential. A basic potting mix such as that used for African violets will also suffice.

Water

Water your begonia thoroughly about once a week, and wait until the top half inch of the soil is dry before watering. It's very important to avoid overwatering begonias, as this can lead to root rot.

Temperature and Humidity

Begonias grown indoors grow best with a consistent temperature range of 65 to 70 degrees Fahrenheit. Fibrous begonias planted in the garden should be all right with cool late summer evenings, but will begin to go dormant once the nights and days turn colder. Being a tropical plant, begonias like some humidity (just under 50%). In houses that tend to have dry air from winter heat, placing a saucer of water near your begonia, or using a humidifier in the room, can help the plant stay healthy and hydrated.

Fertilizer

Fertilizer needs can vary slightly depending on the cultivar of your begonia. For rhizomatous begonias grown indoors, a basic water-soluble fertilizer mixed to quarter or half strength, applied to moistened soil in spring, will help promote blooms. Tuberous begonias are somewhat more hearty feeders, and like a 5-1-1 fertilizer (such as fish emulsion) applied twice a month during the blooming season. For hardy begonias, mix a bit of diluted fertilizer with some compost or peat moss and apply sparingly (too much fertilizer may harm the leaves).

Types of Begonias

The begonia is a large and varied genus with hundreds of cultivars. There are four basic types based upon the shape of their roots: tuberous, fibrous, hardy and rhizomatous.

Tuberous Begonias

The "roots" of these begonias are fleshy round tubers. In colder climates, they're planted as annuals in containers in early spring, then lifted and stored for the winter. The color range of these fluffy flowers includes many brights and pastels (red, yellow, orange, pink and white), as well as the dramatic 'Picotee' variety which have petals that are delicately edged with red.

Fibrous Begonias

This large category includes some of the most commonly grown begonias, including cane begonias (known as angel-wing or dragon-wing begonias) and the well-loved wax begonias (also known as strawberry begonias). They have rounded, shiny, waxy green leaves and the flowers are usually red, pink or white.

Hardy Begonias

These perennial begonias are similar to tuberous begonias but they self-propagate from small bulblets that form on the tubers. They grow up to 2 feet tall and are much more cold hardy than other tuberous begonias, surviving in USDA Zones 6-9.

Rhizomatous Begonias

These begonias have a shallow root system made up of creeping rhizomes. The foliage has large serrated leaves that are often very colorful.

Begonias as Houseplants

Begonias are well-loved as houseplants because most varieties (apart from tuberous begonias) will bloom year round. Fibrous and rhizomatous begonias are the most suitable types for growing indoors. They benefit from frequent deadheading to keep them looking neat and to encourage blooms. Some of the most popular begonias grown as houseplants include:

• Polka Dot Begonia (Begonia maculata): This angel-wing begonia cultivar has gorgeous narrow deep green leaves with silver spots and pale pink flowers.
• Painted Leaf Begonia (Begonia rex): Also known as the king begonia, this is a sub-type of rhizomatous begonia also known for its dramatic foliage. The leaves are deep or silvery green with attractive accents of burgundy or pink.
• Eyelash Begonia (Begonia bowerae): Named for the black edges on its teardrop shaped leaves, this rhizomatous begonia is prized for its vibrant foliage.
  

Pruning Begonias

In addition to deadheading, begonias may occasionally need light pruning to remove any dead or damaged stems or leaves.

Propagating Begonias

Begonias may be propagated from leaf cuttings, rhizomes or tubers. Simply place the leaf cutting in water in indirect sunlight until roots form, then plant in potting soil. Rhizomes and tubers can be pressed gently into moist potting soil and should begin to sprout new growth in a few weeks.

Growing Begonias in Pots

Begonias grow very well in pots, indoors and outdoors. Outdoors, a terra cotta pot with good drainage works well. Indoor containers should also have excellent drainage. As the tubers or rhizomes grow, the begonia will occasionally need to be repotted to give it more room. Just gently lift the roots or tubers and place in a new pot with fresh potting soil, then water lightly.

Common Pests and Plant Diseases

Generally speaking, begonias are not bothered by many pests or diseases. Root rot can occur as a result of overwatering, as can stem rot or powdery mildew. The main pests that can affect begonias include mealy bugs, spider mites, snails and slugs (the latter two enjoy munching the leaves and are easy to remove by hand).

How to Get Begonias to Bloom

Using fertilizer regularly can help keep begonias blooming. The trick is to apply with a light touch, using diluted liquid fertilizer. Never apply fertilizer when soil is dry. Regular deadheading is also essential to keep the plant in tip-top shape and promote maximum blooms. If the flowers seem to be wilting or turning brown, your begonia may be getting a bit too much bright sunlight.