It is possible to shake your silk flowers clean with table salt. Place 1 cup of salt in a large paper bag. Remove a rose from your arrangement and place it into the bag. Holding the end of the bag tightly closed, shake it. The salt particles have a gentle abrasiveness that cleans your flowers. Repeat the process with the next flower until all are clean. Replace flowers in the arrangement. Cornmeal can be substituted for the salt.
This method also requires removing the flowers from your arrangement. Fill one half of a double sink with cool water and add just enough lemon liquid dish detergent to form a few suds. Fill the other half of your sink with clean cool water. You do not want to use warm water because it can loosen glue and cause fading. Taking one stem at a time, swish it in the soapy water. Immediately do the same in the rinse water. It is important to completely rinse the flower, or dust and grime will build up again quickly. Blot the flower with a towel. If no color transfers to the towel, repeat the process with the remaining roses. Replace the flowers in the arrangement once they are completely dry.
Your clothes dryer can do an efficient job cleaning your silk roses. Remove the flowers from your arrangement and place them into your dryer. Set the temperature on cool or no heat and let the dryer run for 10 minutes. The roses come out clean and ready to replace into your arrangement.
This method allows you to keep your arrangement intact while cleaning the flowers. Mix a solution of one part water to one part white vinegar in a spray bottle. Place newspapers or towels under your arrangement holder. Spray your silk roses with the mixture and let them dry. Always test for color-fastness before spraying the entire arrangement.