There are many varieties of begonia, and the tuberous begonia is one of the most popular, partly because of its hardiness. When winter temperatures descend, you may think that your begonias are dead. If the weather is warm enough, they're merely gathering the reserves to sprout again as soon as the temperatures climb. When they do, there may be even more begonias than there were the previous season. To stop tuberous begonias from coming back for good, you must dig up their tubers.
Cut the begonia's foliage back to within an inch or so of the ground. This will clear the way for digging and help you spot the tubers more easily.
Dig up the begonia's roots and tubers. Place them in a bag as you pull them out of the ground. If you leave any behind, they may reroot themselves.
Dig up or till the top 4 to 5 inches of the soil. This will reveal any begonia tubers that you may have left behind. Deposit any that you find into your bag, then compost them with the rest of the begonias and tubers.
Pour boiling water over the planting area. Any small tubers or seeds that you may have inadvertently left behind will be cooked to death.
Pull up any begonias that sprout again despite your efforts (some seeds may have escaped the boiling water). There should not be many--if there are some, this will be the last outbreak.