Remove the extra mulch in spring. The flowers - although beautiful - are just an added bonus. This is a plant that can grow quite large and will always be at its best in a sheltered spot where it can grow while being protected from wind. Dahlia imperialis is a fast-growing, tuberous, herbaceous perennial up to 33 feet (10 m) tall, rapidly growing from the base after a dormant winter period, developing brittle, cane-like, 4-angled stems with swollen nodes and large tripinnate leaves, those near the ground soon being shed. It’s a great choice for a tropical border but may also be grown in a large greenhouse or conservatory, where its chances of flowering are greatly increased. Grow Dahlia imperialis in moist but well-drained soil in a sheltered spot in full sun. Dahlia excelsa, found in the valley of Mexico in 1834, is fifteen to thirty feet in height, like D. imperialis, but produces flowers of a pale rose purple. It has very tall, bamboo-like stems, large mid green bipinnate leaves and large, open faced seven petalled, star shaped flowers in pinky mauve with a yellow centre. [4], Some Dahlia species were brought from Mexico to Europe in the 16th century. That could be a mixed blessing, as tree dahlias are sensitive to frost. Avoid windy locations that could break the stems of your dahlia imperialis. Hardiness to freezing – 23°F (-5°C). Don Mahoney, curator at the San Francisco Botanical Garden, routinely cuts up long trunks into twelve- to eighteen-inch segments with one or two nodes and sticks them upright in a gallon can of potting mix. [4], Some Dahlia species were brought from Mexico to Europe in the 16th century. A leggy and open plant it does however produce extremely pretty flowers. Photographs by RGT. Dahlia imperialis, or bell tree dahlia, is an 8-10 metre tall member of flowering plant in the family Asteraceae. Exposure – full sun, part sun D. imperialis was first described in 1863 by Benedikt Roezl (1823–1885), the great Czech orchid collector and traveller, who, ten years later in 1872–73, went on his odyssey through the Americas. Remove wilted flowers regularly (deadheading). Dig up the tubers and use a sharp knife to cut into sections, making sure each section has at least one eye. The fleshy stems grow singly or in clumps, starting out vertical, but eventually bend in a gentle arc by flowering time. A blend of flower plant soil mix and garden soil is ideal for planting. Name – Dahlia imperialis Family – Asteraceae Type – bulb plant Height – 6 to 13 feet (2 to 4 meters) Exposure – full sun, part sun Soil – enriched ordinary soil Flowering – September to November Hardiness to freezing – 23°F (-5°C) 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. The San Francisco Botanical Garden has grown tree dahlias since 1969. If I should lose this one, I shall try again; fortunately, they are fast growers. All content is made possible by the generous gifts of our supporters. – Discounted admission to select partner events. Dahlia imperialis is a huge dahlia from Mexico that can grow upto 5-8m tall the largest of all dahlias but not quite that tall in the UK. A second tree met the same fate, even though I took more care to protect it. It is also called Imperial Dahlia, tree dahlia, Lehmann dahlia or Bamboo dahlia because of the strong resemblance of its stem with bamboo. We had some exceptionally cold nights this past winter, but my tree dahlia survived and is thriving. Your email address will not be published. Allow tubers to dry overnight before replanting. You must thus first check that your climate allows for planting before purchasing it. The stems are thick and become woody at the base they hold divided velvety dark green leaves this clone also has a touch of purple on the leave and stem. There’s usually no need to stake. It makes a fantastic foliage plant in its own right, however, if grown in a sheltered spot in a mild region, it may bear single, pink-purple blooms with orange-centres, from late October onwards. As with all dahlias, lift the tubers and store over winter. Mahoney has developed a new clone that flowers earlier and continues for a longer period than its parents. No, i did not feed them steroids. Native to Mexico, Central America, and Colombia. In colder climates, dig up and store the tubers in a basement or garage, then divide and replant them in the spring. Dahlia imperialis is a fast-growing, tuberous, herbaceous perennial up to 33 feet (10 m) tall, rapidly growing from the base after a dormant winter period, developing brittle, cane-like, 4-angled stems with swollen nodes and large tripinnate leaves, those near the ground soon being shed. It has very tall, bamboo-like stems, large mid green bipinnate leaves and large, open faced seven petalled, star shaped flowers in pinky mauve with a yellow centre. Mary Wilbur, a native of Wales, worked in the field of psychiatric care, and has gardened in England and New…, Tree dahlia (Dahlia imperialis) flowering in November in a San Francisco garden. How to Plant and Care for the Dahlia imperialis or “Tree Dahlia” To all the lovely people, I had never seen or heard of a “Tree Dahlia”until I enrolled in the Master Gardener class in 2004. It is a plant of the uplands and mountains, occurring at elevations of 1,500–1,700 metres (4,900–5,600 ft), and its leaves are used as a dietary supplement by the Q'eqchi' people of San Pedro Carchá in Alta Verapaz, Guatemala. From November on, I anxiously watch the weather and look for rime on the grass each morning.