The tuberous begonia is regarded as an annual flower, except in the more arid and dry regions (areas where there is no winter frost). It is an indigenous plant to South America and regions in Africa. The flowers of the tuberous begonia come in a wide variety of colors, with the exception of blue and green. They thrive in zones 4 through 6, 15 through 17, 21 through 24 and H1. The tuberous begonias' growth habit varies, with hanging, upright and even trailing varieties.
Growing Begonias From Tubers Indoors
Purchase some begonia tubers in early spring. Typically, dormant begonia tubers are available January through February.
Fill up planting pots with a good quality potting mix to approximately 3/4 full. Water each thoroughly making sure the water flows freely out of their drain holes.
Dig shallow holes for your tuberous begonias to the depth of 1/2 to 1 inch. Place your begonia tubers with the rounded side down, and the indented side up. Cover the tubers up with 1 inch of soil. Water each planted begonia tuber thoroughly.
Place your begonia tubers in an area in your home which is approximately 70 degrees F and has approximately 6 -8 hours of filtered light every day. Water when the soil appears dry, but do not over water; begonia tubers are known to rot if exposed to over-watering.
As soon as your begonia tubers start to sprout (length of time until begonia tubers sprout varies from 7 to 21 days), keep them moist, but not soaked.
Once your begonia tubers have several sets of leaves, and you're certain nighttime temperatures will remain consistently above 50 degrees F, you can move your potted begonia tubers outside. (Please see the Tips section for further information on caring for your begonias.)
Planting Begonia Tubers Outdoors
Choose an area in your garden to plant your tuberous begonias that is well-protected from direct sunlight, and wind. Tuberous begonias prefer filtered light.
Amend the soil in the area where you intend to plant your tuberous begonias, using one part soil to two parts potting mix.
Dig shallow holes for your tuberous begonias to the depth of 1/2 to 1 inch in rows that are approximately 12 to 14 inches apart. Plant your begonia tubers with the rounded side down, and the indented side up. Cover the tubers up with 1 inch of potting mix. Water each planted begonia tuber carefully, don't over-soak them.
Place two planting stakes next to each of your begonia tubers, being careful not to damage the tuber. Stakes will help mark where to water and give the begonia support as it grows. (See Tips for more information on caring for, and maintaining, your tuberous begonia).