Posted: 16/07/2016 at 13:51
Unlikely to work but a tall support cane in addition to the tape may help.
however, wakeshine, I would cut off the broken stem and hopefully encourage further growth from intact stems. Apply a balanced fertiliser too if you do this. .....oh! And stake the remaining stems now with soft twine and do so in several places. I grow pretty tall delphiniums that cope well with winds .....they are supported throughout the stems.