Nice colors and clarity. Please consider straightening up the verticals, especially with advanced editing. I like the lines, the circle on the left, the arc above (complete would be better), and the bench crowned with the brilliant red bush.
I like the quietness of this. I'd rather you not crop out the top of the arch, though - I keep wanting to scroll up which to me means the picture is unfinished.
I Like the lines but the color scheme and the compostion are not too snappy, certainly not for a postcard. A botanical garden postcard should be a lot more foliage and plants, not 80% brick. I do dig how your eyes are led to the empty bench. Put a person there and you change the whole shot.
This is a good photo. I would have liked to have seen the bench centered and more depth of field. The path leads you to a bench that is out of focus. You also should either capture all fo the arc or none of it.