Dahlias are bulbous plants. The older the dahlias are, the larger the tubers are and the more they occur on the same plant. Since dahlias are not hardy and therefore have to be dug up for the winter, you can see at first glance how big the tubers have become.
The bigger, the bushier the individual plant. However, if there are too many bulbs, then you do something good for the plant if you divide it. So you save yourself the purchase of new tubers and can dahlias self multiply.
Dahlias should be divided in spring before being planted in the ground. You can either simply pull the tubers apart. If these have grown together too tightly, the tubers can also be cut off with a knife.
Disinfect the interfaces with charcoal powder
Make sure that the interfaces, i.e. the wounds, are kept as small as possible. If you want to be on the safe side, you can disinfect them with charcoal powder.
Pay attention to individual shoots
You should also make sure that there are always one, better two or three shoots per tuber. This is easy to recognize because they can already be seen in spring.
Re-plant the divided dahlia bulbs and enjoy flowers that are getting bigger and bigger. Because you can share again just two or three years later.