Quick off the mark with a 10ft 6in whopper is Yvonne Light of Aston Road, Southsea.
Yvonne, 50, and husband Ronald are seasoned sunflower growers, and every year they have their own competition with all the family getting involved to see who can grow the most impressive bloom.
This year the couple have outgrown their five grandchildren with their flowers.
Yvonne said: 'We grow them every year and all the family love getting involved – the kids think it's great fun.'
If you think you have a flower to rival Yvonne's monster bloom, we want to hear from you.
Remember, to qualify your flower needs to be in full bloom and we will come out and measure it with our special sunstick. The winner will receive £300 worth of vouchers from Garsons garden centre in Titchfield.
The closing date is August 25.
To enter, e-mail alex.forsyth@thenews.co.uk giving your name, address, daytime phone number and e-mail address and the height of your sunflower.