Begonia ‘Sparks will fly’ and Begonia b.’Bonfire’ (boliviensis)
These are cultivars of begonia boliviensis. This was originally found in the Andes mountains of Bolivia (hence the name boliviensis) and used to hybridize many of the tuberous begonias we have today. The bright flower and contrast of red leaf and heavy veining on ‘Sparks will Fly’ leaves makes for a powerful combination. Mine stayed in a black metal pot on the walkway all summer with very little additional water. I occasionally watered the pot but it mostly received moisture from a sprinkler that was watering the rest of the beds nearby. I also love Begonia b. ‘Glowing Embers’ with a darker foliage and apricot flowers. Begonia b. ‘Bonfire’ glows in the shade with solid green leaves and bright red orange flowers held well above the foliage.
Overwintering
This begonia should be kept in a container for the winter. I remove them from the outdoor pot after a light frost and divide them back into grower’s pots. At this point you can either keep them in the greenhouse (heated) for the winter and enjoy the flower and foliage as a houseplant or help them into dormancy for the winter. If you want to keep them dormant you should start withholding water and cut them back. They may die back after the first frost naturally. You will see a little bit of a tuber in the soil. This little tuber should stay firm in a dark place in the garage or cool dry space with only occasional water to keep it from shriveling. It is important for it not to let it freeze and to bring it back into light in the spring to begin to grow again. Water it more frequently but not soaking while it begins to grow. When there are a couple of leaves you can add a little weak fertilizer to the water and it should start really producing leaves. Harden off in a protected area and move into good warm place with good sun.
Begonia ‘Sensation Apricot, ‘Sensation Red’, and ‘Illumination Orange’
Overwintering
These are super simple too. Again, after the first frost is the time to dig them up. Note not the first freeze, the first frost. If you wait for them to freeze they will die. These will not overwinter in the ground in my zone 7 garden. Cut the tops back to about 1 inch above the tuber. Brush excess dirt off with your fingers and place on newspaper or shredded paper on a plant tray to dry out. Place them in a cool DRY place while they continue to go dormant. Don’t stack them and don’t let them touch. Check them every week and when they are very dry take off the dried stalk and brush soil off more vigorously. Make sure there is no soil in the hollow of the tuber. Store in a cool dry place until spring. At this point you can place them in a box with shredded newspaper left open or with air holes punched in it. Do not let this freeze either. The garage is the best place if it doesn’t freeze.