Boutonnieres are a way to recognize the groom, fathers, grandfathers, and inner circle, and groomsmen at a wedding. Mothers, grandmothers, sisters, and bridesmaids can also wear boutonnieres on their shirts, though those are often called pin-on corsages and are generally a bit bigger in size and include ribbons.
Boutonnieres can either be pinned on or have a magnetic backing for ease in attaching them. I always recommend the magnetic backing for men not wearing a suit coat as it can be difficult and sometimes awkward to pin a boutonniere on a button-up shirt. When pinning a boutonniere, most people will pin the needle through the shirt then through the stems, and then back through the shirt (or suit coat). However, this leaves the sharp end of the needle exposed and the pin visible in photos. A better way to pin on a boutonniere is to start the boutonniere behind the suit coat and pin straight up into the stems on the outside with the first pin, and into the main flower head with the second pin. This makes the pins invisible in pictures and holds the boutonniere more steady without having to worry if someone hugging you could get poked. You can find a tutorial here.
The groom's boutonniere is generally the biggest and has the most variety in it and is a miniature of the bride's bouquet. Often the main wedding color will be used or the groom's favorite flower along with some greenery and filler flowers. Some of the main flowers I use in boutonnieres are spray roses and ranunculus. Every time I put a flower in a boutonniere I wire and tape it completely to protect it from breaking when the men hug others or, as they sometimes do, throw the groom up in the air for pictures and catch him. Or for the groom who doesn't want as 'girly' of a boutonniere I have done all greenery boutonnieres or what I call the 'manly boutonniere' that is made up of just filler flowers, seed pods, grasses, and other quirky flowers, and greenery. Some men just don't want to wear a big bloom. For the flower-loving groom I can also do a bigger boutonniere called a pocket square boutonniere, or as I like to refer to it, a pocket garden boutonniere. These have a magnetic backing and look like a little gathered bouquet sprouting out of the pocket square. I do the magnetic backing as some pocket squares do not actually have a pocket and there may not be a way to slide the flowers into the pocket- fake it til you make it.
The boutonniere gets placed on the left side over the button hole. Boutonnieres are also referred to as 'buttonholes', boutonniere is just the french word for buttonhole.
If you are planning on needing your boutonniere for an extended period of time, for example, if the ceremony is in the morning and the reception is later at night, I would recommend removing your boutonniere and storing it in the fridge during the waiting time. Most refrigerators are the correct temperature to help preserve the boutonnieres and corsages. Especially if it is a hot summer wedding, your boutonniere is out of water and is not guaranteed to last the entire day.
Most boutonniere stems are wrapped in green floral tape, but ribbon can be added to the stems if requested.