The Tree Dahlia

Tree dahlia (Dahlia imperialis) flowering in November in a San Francisco garden. Photographs by RGT

I saw my first tree dahlia a few years ago, as I was walking down a street in the north coastal town of Arcata, California, glancing into gardens on my way. There it was: a multi-stemmed tree in full bloom in mid-November, and close to twenty feet tall. Its light lavender pink, single flowers looked like large, delicate dahlia blossoms. It crossed my mind that someone had given a garden dahlia a dose of Alice’s “eat me” pills for it to develop into this arboreal beauty. I am no lover of the common garden dahlia, but this one captivated me.

My immediate search of local nurseries for a dahlia like this was unsuccessful. Eventually I found a small one at the Farmers Market and planted it with great expectations, only to have it quickly devoured by slugs. A second tree met the same fate, even though I took more care to protect it. I was prepared for failure with the third attempt, but, once started, the tree grew well and flowered in the following November.

When that plant died back after its first flowering...