By Flamingo
Cornwall,
United Kingdom 
My daughter gave me this plant at Christmas. It was a single stalk about 18" high but has grown beautifully through the summer, even though it was late being planted out, to its current height of 5 ft. (I don't garden when it's cold and wet!) She said it was a Bidens but it doesn't look like any Bidens I've seen on the internet.
Can anyone help with its identification, please?
18 Sep, 2013
Answers
Looking around the 'web' I'd say you're spot on. Many thanks.
22 Sep, 2013
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« When do the red leaves form on my red robin tree. gardenjoe
I'd say it was Helianthus decapetalus. Can be a bit invasive, so check where the new growth comes from next year, and if it's spread too much, dig it out before it gets tall. Cut to the ground when flowering is finished.
18 Sep, 2013