Pretty and well exposed. To me, low key isn't just having a background that is dark. It's about painting with shadows. This is a pretty picture but is not low key. Crop it down to the actual content & you'll find it's a pretty normal distribution of tone, mostly middle to light.
Sorry but this doesn't work for me for this challenge. Just because there's a black background doesn't make the image low-key. The visible subject (rose) is not low key at all. It is a lovely photo though.
I find the border distracting in this image, if only because it tries to hold me in. In this image, I'd rather believe there is unlimited space around the flower. The colors are well rendered. The composition conforms to the rule of thirds but there is still a static-ness to the image; for me this might be due to the abrupt cutting off of the bottom due to the border. As a low key entry, I think this image misses the challenge. The lighting is quite bright on the subject even if the background is black. Outside the challenge a well taken image for stock type photography. 5