Gardeners living in regions where begonias will not survive the winter months in the ground must remove them from the soil before the ground freezes in the autumn. Carefully dig up the begonia bulbs and hang them in a warm and dry location for approximately one week. After the begonia bulbs are sufficiently dry, it is safe to store them with peat moss in a cardboard box until it is time to plant them in the spring again.
Dig up the begonia bulbs from the soil in the autumn. Watch the begonia plants for signs it is time to remove them. When the foliage turns yellow and the weather has turned cold enough to frost at night, it is time to dig up the bulbs.
Shake and brush off soil and dirt from around the bulbs. If any of the begonia bulbs appear to be decaying or unhealthy, discard these. Tie twine loosely around the remaining bulbs and hang them from the rafters of a warm basement for approximately one week to dry.
Bring the begonia bulbs down from the rafters after one week and use the garden shears to cut off any remaining foliage down to approximately ½ inch from the top of the bulbs.
Fill the cardboard box about half-full with peat moss and place the dried begonia bulbs onto the peat moss. Ensure that the bulbs are not touching each other in the box.
Place the box in a location with a constant temperature of 35 to 45 degrees.
Check on the begonia bulbs periodically throughout the winter. If you find bulbs with decay, remove these and discard them.