Do I Need to Protect Begonias from Frost?

Climate Considerations

• Prolonged exposure to temperatures below 40 degrees Fahrenheit kills off the begonia roots, so they can only survive outdoor overwintering in climates that rarely experience winter temperatures lower than 40 degrees. In these warmer climates, a thick 4-inch covering of mulch provides sufficient insulation for the roots. The mulch protects the roots only during short, light frosts, so in colder climates you must dig and overwinter the begonia roots in a protected indoor area.

Digging

• Leave the begonias in the garden bed until the first light frost kills back the foliage. Once the foliage dies, cut the plant back to within an inch of the ground. Dig up the root system but take care not to pierce or damage the roots with the trowel as you dig. You must dry the roots after digging, otherwise they will rot during storage. Dry the roots in a warm, well-ventilated room for two to three weeks. During this time the soil that's still adhered to the roots dries. Brush off the dried soil prior to storage.

Storage

• The begonias are ready for storage once they dry thoroughly. Pack the roots in dry peat moss. The moss absorbs any excess moisture from the roots while still allowing air circulation. You can pack the roots and moss in either perforated bags or shallow boxes. A location that maintains a temperature between 40 and 50 degrees provides the best storage conditions. Avoid warm, moist storage areas or ones that may drop below freezing during the winter months.

Replanting

• Regrow the tubers indoors in early spring or wait until after the last spring frost and replant them outdoors in the garden bed. If you start the roots indoors, plant them in a pot of moist soil about eight weeks before the last spring frost. Set the tubers in the soil so the indented side faces up and plant so the top of the tuber is no more 1/2 inch beneath the soil surface. Keep the soil moist and temperatures near 70 degrees Fahrenheit to encourage new growth on the begonias.