Read through all the instructions first before starting this craft, there are three processes that need to happen concurrently.
Wait till your flowers have had their day and are about to fall off their stem. On a hot and dry day pick your petals. Any flowers will work, but roses are the easiest as their petals are big and don´t shrink away to nothing.
In a nice dry warm room that you are not going to need for a while, lay a big sheet of newspaper or brown paper down onto a table. The paper helps speed up the drying process and makes sure your table does not get damaged in the process. Tip: Make sure you spread the petals out well.

Leave the petals on the newspaper for a few days, tossing the petals once a day to help them dry, and make sure there are no bugs eating your petals!

Iris plants should be divided every 3-4 years otherwise the clumps will become woody and produce fewer flower spikes. Splitting the clump is best done straight after flowering, or in late August - September. As you do this you will notice that the youngest and healthiest rhizomes are on the outside of the clump. These are the pieces to replant. The old pieces of rhizome can be used for your fixative.
Don´t worry too much about destroying the plant as they are pretty hardy and don´t mind being handled.
Grate the roots with the fine end of your grater. Place on brown paper away from your petals that are drying.
After two weeks, when the petals and root are properly dry, place them in a bowl with salt and mix it all up. At this point you can add some pencil sharpenings and some small bits of bark. Add a small bottle of aromatherapy oil to the mixture and mix it all again.
Cut out a piece of fabric to 40 cm x 20 cm
Fold the fabric length-ways in half, right sides in.
Sew along the long side.
Sew along the bottom.
Turn the bag the right way out.
Tuck half the fabric back into the bag with the right side showing. Tip: this is done so that there is a double layer of fabric, the inner layer of fabric will help to soak up the oils from the content of the bag and prevent the outer layer of fabric becoming spoiled.
Fill the bag with the potpourri mixture to about 5cm from the top of the bag
Tie a ribbon around the top of the bag to close it, tie it so that you can re-open the bag and re-do the potpourri after a few months when the smell dissipates.

Hang your bag of potpourri in your closet, or place them on a door handle around the house to make the house smell nice. Remember that lavender is a wonderful deterant for moths, so make a bag or two with lavender chopped in and you wont have any need for moth balls. Place one or two in book shelves to save your books from getting eaten.