He must have had the Sunflower stalk tied to a sturdy pole or stake. Mature Sunflowers tend to droop and lean because they’re top-heavy.
He also must have had some protective mesh covering the plant.
The Red Winged Crow and the Sparrows would love to have at all those seeds.
Inscect spay would be need against the Beetles, but probably nothing as potent as Round Up, which would kill the Sunflower too.
Yes, it was tied to a wooden scaffold.................