I like the composition, with the subject being in the bottom right third of the frame. I think you took this at the wrong time of day, the shadows are strong and some detail is lost in them.
Excellent concept. Definitely a mundane subject made extraordinary. The red of the concrete is a great contrast to the green of the weed and makes it pop out of the shot. Love the leading lines that the concrete , makes you eyes focus on the weed itself. The white of the weed gives an extra touch of beauty to the ordinary weed. From a "9" to a "10".
Good job making a plain old weed look interesting. This is a perfect example of how a Levels layer adjustment could make this look better. Good job anyway!
Typically i like shots like this a lot, but there's something about the color and the darkness of the exposire that throws me off... it also seems a bit soft.