1. Take out a large metal or glass bowl (plastic and wood are too porous, and would absorb the scent of the essential oil), and a metal spoon (again, no wood or plastic). Pour in the Epsom salts and sea salts and mix well.
2. Let the five drops of red and five of blue food coloring fall spread across the surface of the salt mixture. Then do the same with the drops of lavender essential oil. Mix thoroughly. This can take a lot of stirring, since the food coloring and essential oils tend to want to clump together. Be persistent, and try to break up any clumps that you see. Once there are no longer any clumps of food coloring (these are easy to spot) you can generally count on the essential oils being well-mixed too.
3. Now add the cup of baking soda and mix well. The baking soda needs to be added last, because it works much better if the essential oils and food colorings are spread thin first (they would clump much worse if added to a mix with baking soda in it).
4. Finally, mix in the dried lavender blossoms. These are added last so that all of the mixing doesn't beat them up too much.
5. Put the bath salt mixture in an air-tight glass or metal container. You can use a plastic baggy, but be sure to discard it afterwards, because it will have absorbed some of the essential oils.
Directions for Use:
For a standard-sized bathtub, simply add a cup of bath salts to the water and allow to dissolve. Double it for a garden tub. Do not use bath salts with dried flowers in them in a tub with jets (the flowers will clog them).