Answer: With patience and proper pinching almost any woody perennial can be trained into a tree shape. Fuchsia, Marguerite, Heather and Rosemary make interesting subjects. But a dahlia grows from a tuber and has soft (herbaceous) tender stems that die back at the end of the season, so training them into trees would be difficult, indeed. Perhaps the dahlia tree you saw was a differnt plant with dahlia-like blossoms. Why not contact the folks at Sunset and ask them for a source? Sunset, 80 Willow Rd., Menlo Park, CA 94024 Phone (800) 777-0117.
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