I bought what I thought was a C. radicans several years ago, hoping that it would grow quickly and covering a fence. I later found label saying 'Μπιγνόνια' which I then learnt was not a Bignonia, but a C. grandiflora. It has barely survived, is till less than one m tall, has never produced any flowers. At least this year it at least looks healthy, but I wonder what I should do to get the strong growth I was hoping for?