Here's a great way to have dried flowers last longer, put in a shadow box. You can make your own with any box about 4" deep that is the dimensions of the opening and cover with decorative tissue or handmade paper. There is a bunch of baby roses, blue, lime and peegee hydrangea, yarrow, berries from a palm tree in this arrangement.
Also make a box out of some heavy paper sprayed with gold paint splatter inside the box to hold the flower arrangement. Do the arrangement first then wire the box onto the frame. Hang in an area out of direct sunlight and in a dry area, not in a bathroom and inside of course although I took this picture outside.
This one was done years ago and given as a gift and the flowers inside finally faded. I was asked to redo the arrangement and now it's freshened up and will last for several more years.
This idea was seen in a shop years ago and it was 200.00 so I thought I would make it myself. One of those things I saw that I really did go home and make. One time I saw a sign at a craft fair in a booth and it said "sure you can make it but will you"? So true, I see so many things I could make but never end up doing it.