Tuberous Begonias, like our Santa Cruz Sunset, REQUIRES winter dormancy. This means you need to begin in fall by reducing the water to the plants until the tops have died back and the soil is completely dry.
Here is my shortcut: Forget to bring in the basket on the night of the first freeze! See the results in the photo below.
Once the plant has gone completely dormant most gardeners remove the tuber from the soil. The tuber is usually found where the stems meet the ground. Carefully clean off the tuber of soil and old roots and store in a warm dry location over the winter. Some gardeners swear by a fungicide powder to control diseases on the dormant tuber, this can be applied before storing the tubers.
In early spring the tubers may be replanted in fresh soil and given a head start on the season in a bright windowsill where they do not become chilled. The tuber should be planted so that the upper surface is at the surface of the soil, no deeper. When planting the tubers, water them well with a light fertilizer and do not water again until either the soil dries or you begin to see new stems emerging from the soil. Most gardeners start their tubers in small pots 4”-5” this way they can be transplanted into larger pot later but they do not become too wet during the crucial period where they waking up and beginning to grow.
New growth means your tubers are beginning to grow new roots and need to given fertilizer and water on a regular basis. Never allow tuberous begonias to become soggy, they are very sensitive to root rot if they stay too moist. Examples of Tuberous type Begonias include the following: Santa Cruz, Illumination, Non-Stop, On Top, Ornament, Panorama, Pin Ups, and Charisma series.
As with all garden plants brought indoors for the winter, you may have good luck and you may not. Remember that if all of this seems like too much work you can simply buy new plants in spring and start clean. Also Begonias can be prone to a variety of bacterial and fungal problems, especially under indoor conditions, so if you see problems of this type showing up during the winter, contact your local garden center for advice on how to control any problems.
Date Moved Outdoors: March 1 2017
First Leaves: April 1 2017
First Flower: May 2 2017