Answer: Seed grown dahlias are often sold as bedding annuals in the spring. Over the summer they usually mature and develop tubers that can be handled the same as any other dahlia. So the propagation method would be the same. Lift and store the clusters of tubers, then divide them carefully so that each individual tuber has a bit of stem attached to it. Without a bit of stem, the tuber will not grow.
Q&A Library Searching Tips