Is the spacing of my grafts too far apart? (Photo)

Crown cases are the most difficult to obtain good density, and it often takes a large amount of grafts. The answer to your question comes back to how much hair was in the grafted area before the transplant. If there was very little hair in your crown I doubt that the grafts in the photo are going to make a big impact.

The grafts seem to be spaced appropriately for the amount of area covered. Use minoxidil topical nightly and be patient for the next several months for the bulbs to sprout.

Although it seems to implanted less than enough in vertex area, remember that the result of the hair restoration surgery  depends on the hair quality (color, color difference between skin/hair,  thickness of the hair, curviness or straightness etc).