Useful in Gertrude Jekyll-type border planting schemes. Dahlia imperialis, the tree dahlia. Growing up to 12ft tall, it looks perfect in a hot, tropical border and there’s no need to stake, as the ...

coccinea and D. sorensenii. The genus also includes the spectacular Bell Tree Dahlia (Dahlia imperialis), which grows over 20 feet tall in my garden and can reach greater heights in its natural ...