When is bloom period for lady slipper

Early June is the best time to see them flowered. We were there on June 7 and some had already gone by

I did not see any this July.

I was just walking through the area and saw several clumps of them on the Maine woods trails. They were just starting to grow the bud of the flower. I heard from others that day that a few were in bloom but I never saw any personally. I'd say May 28th-31st would be safe dates to see them starting to be in bloom.