Native to the tropical climates of Central and Southern America, Indonesia and Southeast Asia, begonias are tender annuals in all but the warmest regions of the U.S. Grown successfully outside during the summer months, they require over-wintering inside the home and make a delightful houseplant. Although there are over 1000 species of begonias, wax begonias are the most common begonias grown inside. Not only do they bloom profusely throughout the year, their attractive foliage ranges from glossy green to rich bronze, creating a colorful display even when not in bloom.
Plant begonias in a soilless potting mixture. Mix two parts peat moss to one part perlite to create a lightweight porous mixture. Although begonias will survive in all-purpose potting soil, according to the American Begonia Society a soilless mix or straight peat moss is a better choice, as it holds the right amount of moisture and prevents damage from over-watering.
Keep begonias in pots that are slightly larger than their root ball. Begonias planted in pots that are too large for their root system suffer from soil that remains moist for too long. Repot to the next size pot when roots fill the pot.
Water when the surface of the soil dries. Allow water to drain freely through the bottom of the pot. Empty the saucer and allow begonias to dry before watering again.
Mist daily to raise the humidity level near begonias. Begonias thrive in high humidity and suffer if humidity levels are too low. Pebble trays or humidifiers placed near begonias improve their health.
Fertilize with water-soluble fertilizer mixed to ¼ strength once a week during periods of active growth. Reduce to once a month during winter months when new growth slows.
Place in bright filtered light. Those with bronze or red leaves can tolerate more light than green foliage. If leaves show signs of burning or growth is stunted, move to an area with less light. Plants that stretch toward the light and become leggy require more light. The amount of light required depends on the particular species. Most can be grown successfully in all but north windows and will thrive under artificial light.
Pinch out center leaves regularly to encourage a compact plant with lush foliage. Overgrown plants can be trimmed back to several inches high. Root stem cuttings in a jar or vase of water to create new plants.