Data posted in the thread here on increasing herb yields indicates that Croppery does have an impact on shucking herb seeds, at the very least, so the answer appears to be "some, though the full impact is unknown".
Yeah, Croppery 1 will give +1 of the herbs that give 2 with each harvest. So, purple, silvertongue, and yellow crumb will give 3 each harvest instead of 2. The others, that only give 1 with each harvest, won't be affected.