How do you divide Dahlias?
If you have a dahlia plant in the garden that is looking a bit overgrown and untidy then you can rejuvenate it by the simple process of division.
Dahlias grow from tuberous roots that are very like sweet potatoes. Each torpedo-like swollen root has a number of buds at its top end. A large dahlia clump will consist of many of these tuberous roots, groups of which can be split off to form a new plant.
Once the plant yellows off in autumn, then cut it back. Leave till mid winter to divide. Use a garden fork to get underneath the clump and lift it, shake off the excess soil and separate the smaller clumps of roots from each other by gently pulling them apart. The process will multiply the number of plants you have so if you do not wish to increase the area planted to dahlias in your garden then the excess can be given away. It is an ideal time to fertilize the growing area once the clump has been lifted, by digging a complete garden food into the soil into which you are replanting.