Posted: 26/03/2014 at 10:27
Sarah, the email function has not worked for about a year; just keep checking 'followed threads'.
You could also try Hollyhocks for height, though it is difficult to get the single variety except in almost black; I find the doubles look rather like pom-poms. Cosmos also grows pretty tall also Verbena Bonarienses.
Good luck with it and post some pics later in the season