Dahlia imperialis

The impressive Dahlia imperialis reaches heights often in excess of 250cm—in a single season! In their native environment (Mexico, Central America and Colombia), they can even grow to 8-10 metres tall. For this reason, it goes by several common names, including bell tree dahlia, giant dahlia or just tree dahlia. Its long, thick, bamboo-like stems are clothed in large, elder-like, fresh green leaves, making it a fine and splendid foliage plant. To ensure flowering, it needs to be grown in a frost-free situation. A warm autumn is when you are most likely to get the best flowering. When they come, the single blooms are of a gorgeous soft pink-purple, with orange centres.

Grow Dahlia imperialis in a moist but well-drained soil, in a sheltered spot in full sun. It is an ideal dahlia for a tropical border in the garden, or you can grow it in a large greenhouse or conservatory, where its chances of flowering are greatly increased. Its stems are so sturdy, there is usually no need to stake. As with all dahlias, lift the tubers of the bell tree dahlias and store them frost-free over winter.