Rust: the perfect finish
For me, rust provides the perfect organic appearance for an otherwise rather industrial material.
When steel first starts the oxidisation process it's orange, unstable and it will come off on anything it touches. After a while, it gets darker in colour and becomes more stable.
Some more good old English drizzle and it will turn a rich burnt umber colour; this is the final stage and it will no longer come off.
The steel has now formed its own protective coating and because I use heavier steel than garden centre plant supports it will last many, many years.