As a begonia, my life is a cycle of vibrant growth and essential rest. The question of dormancy is not a simple yes or no, for my extensive family has diverse habits. However, for many of my tuberous and some of my rhizomatous cousins, the answer is a definitive yes. It is our way of surviving the cooler, darker days when the sun’s energy is too scarce to sustain our beautiful foliage and flowers.
We do not follow a human calendar. Instead, we are exquisitely tuned into our environment. The primary signals that trigger our dormancy are the decreasing hours of daylight and the gradual drop in temperature. As autumn progresses, the weaker sunlight means our photosynthesis process becomes less efficient. Simultaneously, cooler air and soil temperatures signal to us that a challenging period is approaching. In response, we begin a deliberate process of shutting down. We stop producing new flowers and slowly halt leaf growth. Our goal is to conserve every bit of energy we have stored in our specialized parts—tubers underground or tough rhizomes at the soil surface—for our rebirth in the spring.
From your perspective, it may look like we are dying, but please understand this is a natural and necessary slumber. You will first notice our flowering cease. Then, our leaves will begin to yellow and brown. This is not a cause for alarm; it is us actively drawing valuable nutrients back from our leaves into our storage organs for safekeeping. The leaves will eventually wither and drop. For tuberous begonias, the entire above-ground structure will die back completely. For rhizomatous types, like the Rex begonias, we may retain our rhizomes but our foliage will often die back significantly or completely.
This is the most critical time for you to understand our needs. If you leave us outside in freezing temperatures, we will perish. For those of us with tubers, once our foliage has yellowed, you should carefully lift our tubers from the soil. Brush off the dirt, let us dry in a cool, airy place for a week or two, and then store us in a box of dry peat moss or vermiculite in a dark, cool (around 45-55°F or 7-13°C), and dry location for the winter. For my rhizomatous family, you can either keep our pot in a cool, dark place and water very sparingly (just enough to prevent the rhizomes from completely desiccating), or you can lift and store our rhizomes similarly to tubers. We require almost no water during this time—too much will cause us to rot.
It is important to mention that not all begonias experience a deep dormancy. Many fibrous-rooted begonias, such as the wax begonias (Begonia semperflorens), are often grown as annuals and are discarded after the season. However, if kept indoors as houseplants in a consistently warm and bright location, we can continue to grow year-round, though our growth will likely slow during the winter months due to lower light levels. We appreciate reduced watering and no fertilizer during this slower period until the stronger light of spring returns.
