More DoF fun!

On my walk today I noticed tulips in bloom in front of a road name plate, I saw that there was just one isolated yellow tulip, the others being pink, as you can see.  So I saw the composition including the road name sign and thought I could use a narrow depth of field to isolate the single yellow tulip. Anyway in theory it sounded good, my 50mm lens was wide open and I moved in close as I could with this lens.  But when I see the image on screen the eye is not drawn to the yellow tulip as I thought it would be - the word Road seems to dominate the image.  So you don't always get it right!