|Hello from the Critique Club.
As has been pointed out, your resizing has left your image very pixilated. It is especially visable on the leaf stem and around the edge of the pot. I can't offer advice on how to upload. I use Photoshop "Save for Web". There is a tutorial which might help you. Many people with your camera upload very crisp pictures so I can only suggest that you need to do more research.
Probably the low resolution issues hurt your score more than anything else. I suspect it cost you a whole point. I think your focus is right on the leaf where the stem joins and the rest of the image is out of focus. So as a DOF exercise you were successful. The focus on the jagged edges of the leaf is nice.
Your composition leaves a lot to be desired. Composition is a large part of photography. Is the image pleasing to the viewer or if not, does it catch his interst in another way. Whatever can make the viewer look at your image longer, especially here where the voting can be done so quickly, increases the chance that he will see what you were trying to portray. What were you trying to tell the viewer here? Why should I look at this image any longer than to determine that it is a young plant in a pot?
Leading lines is one design element that is effective in catching the viewers eye. Unfotunately all your leading lines lead the viewer OUT of the image and in the DPC voters mind this means "Done, next picture". See how each of your leaves points out like an arrow, and the leaf at the bottom with the nice curve also points out,
You have placed your center of focus at one of the rule of thirds points, but the rest of the plant makes it dead center in the frame. A centered image, for some reason probably biologically rooted, is less interesting to the human mind than an off center image. You background is uninteresting to the point of being unattractive. Perhaps a tighter crop would eliminate some of the brown dirt.
In summary, as a homework assignment on Shallow DOF you have been very successful, in a class you would get a good grade. As a contest entry where the whole image as important as the challenge topic you have recieved a lowish score, but not a failing one. Better luck next time.