46+ Begonia Flowers Turning Brown. I have several begonia plants.they were all planted at the same time,but in the last few months i have noticed that some of the plants are turning brown and some are looking really good,nice and green and lots of flowers.about 4 months ago i repotted them into larger containers with fresh. Watery brown lesions on a begonia's flowers, leaves or injured tissues typically signal a botrytis infection.
The leaves and flowers of begonia plants grow out of these joints.
Lacecaps also brown in too much sun, but even in shade these types of flowers might not last as long as other varieties. Cool nights and hot humid days will cause pm among other things. This is in response to a couple of questions i've gotten about bromeliad flowers turning brown. Powdery mildew can cause leaves and flowers to turn black.