How do I avoid moths hatching in my homemade potpourri?

I pick flowers from my garden and dry them naturally, without using a microwave or oven. After a few months moths hatch out and start to eat the flowers. I have tried freezing the dried material for a period of time before making the potpourri but still end up with moths.

How do I avoid moths hatching in my homemade potpourri?
I would try a solution of 1/2 water and 1/2 bleach and mist the flowers with a spray bottle and then let them dry out naturally. This should eliminate the moth larvae, and the bleach will degrade on it's own as the flowers dry.
Reply:YOU COULD RINSE THE FLOWERS WELL BEFORE YOU DRY THEM. POSSIBLE WITH VINEGAR WATER RINSE.