Tuberous Begonia’s have a reputation of being a challenge to grow and that reputation is somewhat well deserved. I’ve grown them myself and I’ll admit to having mixed results with them. I think these results are more about my growing conditions rather than the Begonia’s themselves but the more I learn about these beautiful flowers the more I’m convinced that they belong in my garden plans. Hopefully, after reading this article it will give you the confidence to try them yourself!
There are over 1,000 varieties of Tuberous Begonia’s which can really be divided into 2 different categories; upright vs. hanging. Upright varieties can grow up to 3 feet tall and hanging varieties are good choices for containers. This plant is native to the Andes Mountains of South America where they thrive in an environment that is very humid but also has cool night temperatures. It is sometimes challenging to match such conditions here in the United States but Tuberous Begonia’s seem to do best in shady conditions where they get bright but not direct sunlight such as would be associated with exposure to morning or late afternoon sun. The hotter the conditions the more shade the plants will need and if a hanging Begonia starts to grow upright that is a sign it isn’t getting enough sunlight.
The tuber for this flower is about the size of a potato but it is flat. The bottom of the tuber is rounded and the top is flat with the exception of a depression in the middle of the tuber. When they start to sprout they have what look like white to pink nubs that appear on the top side and this is a signal that the tuber is ready to be planted. The tuber should be planted with the sprouts covered by about ¼” to ½” of soil. It can take up to 3 months for the Begonia’s to bloom but you can get a jump on the season by starting them indoors up to 6 weeks before you would plant the tuber. These are very frost sensitive plants so in many garden zones you’ll have to wait until Mother’s Day to plant them. This means if you wanted to start them indoors you would do so in late March.
Tuberous Begonia’s will tolerate a variety of soil conditions but it is important that the soil drain well as too much moisture in the soil will rot the tuber. Upright varieties are subject to wind damage and will benefit from stakes or supports which I would insert at the time you plant the tuber or you’ll risk damaging it if you try to install them later in the season. You can fertilize them monthly throughout the growing season. Removing the spent flowers will help the plant continue flowering all summer long. When watering the plants you’ll want to try not to water the leaves as this can lead to diseases such as powdery mildew. The blooms can be single, double or ruffled and the flowers come in a variety of colors including white, red, yellow, orange and picotee which have contrasting colors on the petal edges.
Unless you live in garden zones 9 or higher you’ll need to lift these tubers and store them over the winter if you wish to grow them again the following year. Once the first light frost has killed the foliage you take the tuber out of its container or the flower bed it was growing in and place it in the sun for 4 to 5 days to dry the tuber out. You’ll then brush the dry dirt off and let the tuber sit for another day or two to make sure it is totally dry. You can then take the tuber and cover it with Sulphur powder or baking soda to help prevent the growth of diseases and place it in a container or box lined with peat moss or even shredded paper. The container or box should then be placed in an unheated basement or corner of the garage where temperatures won’t go below 45 to 50 degrees and in the spring, you can start the process all over again.
Tuberous Begonias are very beautiful and the blooms can be floated in a container with water for an exotic looking table centerpiece. While they may be somewhat challenging to grow I think their beauty makes them worth the effort and hopefully, once you’ve tried them out you’ll agree with me!