Ever since I posted about this unusual Bidens almost exactly a year ago, I have noticed that it keeps showing up in the ‘top posts & pages’ so readers are obviously interested in it and how it performs. I thought it was late to flower last year because I had grown it from seed in March and it was going to need several months to attain it’s height and maturity. When it did flower it was stunning in it’s simplicity. Dainty and delicate white tipped canary yellow flowers on tall wiry stems. Frankly, when it died away last winter I didn’t expect it to re-appear, and so I was delighted when it did. Bidens is not generally considered to be hardy but this variety is reckoned to be hardier than most.
Bidens aurea 21 May
It was probably due to the very cold and wet spring this year but it took forever to appear and it was the end of May before I noticed any new growth. However, I was delighted to see far more growth than just the three plants from 2012. It had spread several feet and now covered an area 1 metre across. This fresh young growth sat reluctantly through spring and didn’t do very much until the end of July when it suddenly took off and the first flowers finally appeared at the end of August, exactly the same as last year!
If anything, I think it might be slightly shorter this year which may be due to the horrible clay soil it sits in and the corresponding lack of nutrients but the foliage colour is a good dark green and it looks very healthy. The flowers, three or four at the top of each stem, open successively and seem to last a week or so before the next bud opens. 
If it spreads again next year I may have to re-classify it as invasive because, as much as I like it, I don’t want it to take over the border. It is already swamping a few things so a bit of division is called for next year. A number of visitors from our horticultural society have asked for a piece so it will end up in several more gardens.
A plant I can heartily recommend. If only it was scented!
Davids Garden Diary 
Highly invasive! And very persistent. The roots run in amongst everything else in the border, and it regenerates from the smallest piece. I made the mistake of planting it in two customers’ gardens as well as my own 3 years ago, and still haven’t managed to get rid of it. Pretty as it is it’s a menace.
Hi Alex and thanks for your comment. I agree it runs a bit but I don’t agree that it’s highly invasive. It is nothing like ground elder!. I have a bigger problem with the white sterile form of willowherb which runs for miles! I have found that this Bidens loses vigour after a few years and is now shorter and less floriferous so, who knows, it might just give up!
I made the mistake of planting this lovely plant bringing it from a deep clay area where it didn’t run so much to a agricultural clay/green sand area in pewsey wilts and within 2 years it’s become very troublesome. It disappears in winter this is the time it spreads from its underground pinky root system . Only to start popping up in May. Like acanthus if dug up it splinters leaving small roots to carry on . I doubt I will ever be rid of it as it travels underneath other perennial plants in winter. And would have to dig up my large newly planted garden of 2 years
to try to get rid of it It reminds me also of field bindweed in the way that it digging it up just seems to promote the problem. I dug out a problematic square metre of it in May sieving all the little pieces of root took me about 4 hours only to find the same area re- sprouting within 2 weeks. I would beg anyone that doesn’t know what they are doing like me not to plant this. If you look on American web sites you will see bidens is an invasive plant. Maybe with the u.k. warming it has acclimatised in winter and is not killed off in winter?
Hi Alistair and thanks for your comment. My Bidens disappeared after a few years. It began to get shorter and sparser and then finally died out. Mind you, it was in clay, probably not ideal for a running plant. Invasive in the right conditions but still a pretty flower!