I have to confess beyond the fact I know it is the formula for making perfect spirals I don’t know much more about Mr Fibonacci. Looking up this page helped a little, well the first paragraph did where it explains you just add the two previous numbers together to get the following one. Once those diagrams kicked in I was lost.
Anyhow the point is for the first time in three consecutive years of planting I managed to grow two Giant Russian sunflowers. They were massive, a good two metres tall with thick trunks and flower heads at least 60cm across. I have just picked them and will dry the seeds for planting next year