This is a close look at a beautiful "Tree Dahlia" species - Dahlia tenuicaulis.  It grows to 15 feet tall, with dramatic, bamboo-like canes topped with purplish-pink blooms.  There are other tree-sized Dahlia species but they only bloom in winter, while this one is ever-blooming, with flowers appearing almost all year long!  The plant comes from southern Mexico, where it is rare and at risk of becoming extinct.  It is rarely seen for sale.

 Dahlia tenuicaulis (pronounced "ten-yoo-ee-KAW-liss") is unusual in that it has perennial canes that tend to stay evergreen in frost-free areas (including indoors).  The canes grow about 1 to 3 inches thick, and the plant has a bushier shape than my other Tree Dahlia, Dahlia imperialis.  Here in San Francisco it grows to about 15 feet tall and 8 feet wide, although you may prune it to any size that is convenient.  The blossoms are 3 inches wide and are lightly fragrant.  They appear from spring through late winter, with the heaviest show in autumn.

Dahlia tenuicaulis comes from mountain cloud forests, where the temperature is mild all year and nights are cool.  I don't have much information on its climate tolerances, but it's possible that it may not flower during hot weather with warm nights.  The tubers are probably hardy down to about 20 degrees F (-7 degrees C) if planted deep.  In colder areas, you may grow the plant in a pot and move it indoors for the winter, pruning it to the base if desired.  This Dahlia seems to prefer part sun, and will probably want some protection from strong afternoon sun.  Like most Dahlias, it likes well-draining soil, and adequate watering and feeding.  If the plant goes dormant in cold weather, keep the tubers relatively dry.

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Rooting the cuttings