There are more than 2,000 accepted species of Begonia, many from the tropic to subtropic environments of the Southern Hemisphere, but some from ranges extending north through Mexico and Central China. Begonias may be grown for their decorative foliage, for attractive flowers, or both. Plants have both male and female flowers, growing in clusters of one type or the other, from a leaf axil. Male flowers are often more showy and drop off a few days after opening. Female flowers have interesting, three -part ovaries dangling behind the flowers and can last on the plant for weeks. Begonias can make great houseplants and the types grown in the home are generally divided into categories of care based on their root systems: fibrous, rhizomatous or tuberous.
Winter flowering begonias (Begonia × hiemalis) may be sold under the trade names Rieger begonia or Elatior begonia. Those names are associated with 20th century breakthroughs in breeding and have become attached to these plants, though they are no longer considered correct names for the hybrids as a group. Complex hybrids of diverse, tuberous-rooted, plants, these semi-tuberous begonias do not fit neatly into the three growing categories and have inconsistent roots. They captured the hearts of growers for their winter bloom cycle with large, mostly double or semi-double flowers. Plants, including almost 500 cultivars, can be found for sale year round and are typically kept as a temporary decoration and then discarded.
They need bright, filtered light with no direct sunlight. The light near an east-facing window is ideal, or further from a south- or west-facing window.
These begonias grow best at 60 to 65º F. to extend the period of flowering. Avoid hot and cold drafts near heat vents or cold doors and windows. Do not expose to temperature below 50º F.
When the top inch of soil feels dry to the touch, water thoroughly in the morning using tepid water. Discard excess water from the run-off dish after 15 minutes.
A relative humidity above 50% is preferred to successfully grow winter flowering begonias. Provide additional humidity by misting twice daily, standing plants on shallow trays filled with moistened pebbles and/or using a humidifier. A simple hygrometer kept in the area of the plant will help you to monitor air moisture.
Fertilize every two to four weeks when the plant is in active growth with a dilute, water-soluble fertilizer (15-30-15).
Take 3"cuttings after flowering has finished and let them harden off for 10 days before transferring them into a light soil mix.
Pinch above the leaf node to promote bushier growth.
Leaves will yellow and fall off if the plant doesn't have enough light or if it is over- or under-watered.
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