Showy, colorful and richly textured, tuberous begonias bloom all summer long in shade or partial shade. If watered and fertilized adequately, tuberous begonias will thrive through the growing season. These shade-loving plants require a dormant period every year but they will not survive sub-freezing temperatures. Tuberous begonias must be dug up and stored in growing regions colder than zone 10. With proper care, they can be dug, stored and replanted every year.
Learn your frost and freeze dates. The foliage and flowers of tuberous begonias will die back in a frost but the tuber will survive. A hard frost, however, will kill the tubers. They must be dug up prior to your freeze date.
Stop fertilizing tuberous begonias in late summer. Throughout the growing season, these plants benefit from regular feeding with a water soluble 10-10-10 fertilizer.
Reduce watering frequency in late summer. Tuberous begonias require regular watering during the growing season, particularly if they are grown in sheltered areas under trees or on covered porches. In late August or early September, gradually reduce watering frequency by half.
Remove flowers buds that form in late summer. In mid-September, pinch any newly formed flower buds to encourage dormancy.
Dig the tubers at least 2 weeks before your freeze date. Cut back the foliage to about 5 inches. Do not shake the excess soil off the tubers. Lay tubers on paper towels or newspapers in a cool, dry area and allow to “cure” for 2 to 3 weeks. After curing, shake off the clinging dirt and cut off the excess roots and stems. Do not wash the tubers.
Fill a perforated plastic bag or box with vermiculite, peat moss or wood shavings. Bury the tubers in the storage medium and keep them in a cool place where temperatures range between 40 and 55 degrees Fahrenheit.