According to the search results, a boutonniere should be placed on the left lapel of a suit or tuxedo jacket. Specifically, it should be placed on top of the lapel and aligned with the sides of the lapel so it angles in the same direction. The stem of the boutonniere should be aligned with the sides of the lapel so it angles in the same direction. The boutonniere is typically placed lower than the tie, but above the pocket square. If someone else is pinning the boutonniere on you, it should be placed to the right of the tie.