Available in white, red, purple and pink, calla lilies are delicate cone-shaped flowers that do well as cut flowers. To preserve calla lilies, you may dry or freeze-dry them. Freeze-drying is a complex process, and is usually only done by professionals who own the proper equipment. A freeze drying machine will both lower the temperature and use a vacuum mechanism to remove moisture from the flower. Freeze-dried calla lilies may be used in arrangements and are long-lasting.
Select flowers to be freeze-dried. Cut flowers and place in a container with water for at least 12 hours.
Remove each flower from the water and strip the stem of leaves. Cut the stem to the desired length.
Turn on the freeze drier and vacuum and set it to -5 degrees Fahrenheit. Turn on vacuum for 10 seconds to seal door. Proceed to next step when machine reaches -5.
Turn off the vacuum, open the machine and place the flowers in the chamber, setting them a few inches apart. To load flowers, remove racks from the freeze drier, fill each rack and place it back into the machine.
Close the machine door and turn off the interior light. If there is a window in the door, cover it with blackout fabric. Turn on the vacuum. Leave the flowers in the machine for 24 hours.
After 24 hours, set the machine to 0 degrees Fahrenheit and turn on the vacuum. Leave the flowers in the machine for 48 hours. Repeat this process in 5-degree/48-hour increments until you get to 20 degrees Fahrenheit.
Carefully open the chamber and remove flowers with care. Flowers may now be used in arrangements or for decoration.