Hello I am hoping you can help me with my begonia which is about 15 years old. It is 18″ across and about 10″ high and grown in a hanging basket which receives early morning sun under a gazebo. This is the first year I am concerned about it and as you can see a there is something definitely wrong. Can you tell me what it is and what I can do about it. I am also wondering if this will impact its ability to come back next year and if I can over winter it this year. I hope you can advise.
Looking forward to hearing from you
From your photo it is difficult to tell exactly what is wrong with your begonia plant. I see a dried up leaf and brown patches on other leaves. Have you noticed any pests on your plant? Usually, the spots & brown patches on the leaves are indications of inconsistent watering which isn’t surprising given the weather we’ve had this summer. They also hate hot weather which may also be a factor.
You do not mention how often you water your plant or if your plant has been transplanted or divided in the last few years. Have you been feeding your plant regularly?
Tuberous begonias grow best in well-drained soil in an area where they receive good in-direct , dappled light. Even though tuberous begonias prefer well-drained soil they are not drought tolerant. Allow the soil in containers to become slightly dry before watering. Tuberous begonias are fairly heavy “feeders”, so fertilize with a dilute balanced (20-20-20) fertilizer throughout the growing season (April-August) for best bloom and growth.
You might want to consider dividing/propagating or repotting your begonia in the spring. You may want to consider a bigger pot next season since they do better when they are not overcrowded. Begonias tend to perform better in late summer as the weather cools down.
All tuberous begonias enter a dormancy period during the winter. For step by step instructions on prpagating/dividing your begonia see Tuberous Begonias by the University of Minnesota. You may also wish to see some of our archived posts on Tuberous Begonias and our Garden Guide on Growing Begonias Indoors.
Lastly, if you do decide to repot your begonia in the spring check the tubers for rot. Begonias are susceptible to a number of fungal diseases. This link from the Connecticut Agricultural Experiment Station, lists potential fungal diseases for reference: https://portal.ct.gov/CAES/Plant-Pest-Handbook/pphB/Begonia-Begonia
Good Luck with your begonia.