Put the blossoms still attached to their stems and leaves into a large bowl filled with clean cold water. Swish, let the dirt settle, lift up the calendula, and empty the water. Repeat this step at least one more time or until the water runs clean.
Place the calendula on a towel to dry. Cover with a second towel and gently blot.
Cut off the blossoms near the base and arrange them single layer on your dehydrator's shelves. Leave a bit of space in between each blossom.Arrange the stems/leaves single layer on separate shelves. Turn your dehydrator on. If there is a thermostat, set it to 125ºF.Please note that other websites suggest setting the thermostat to 95ºF; however, I find that it takes approximately 24 hours for the base of the blossoms to completely dry at that temperature. At 125ºF, the blossoms will dry in 8 to 10 hours, and the petals do not become "cooked." Rotate the trays periodically from top to bottom. When rotating, also turn the trays around since the back of the dehydrator may be hotter than the front.If your dehydrator doesn't have a thermostat or circulating fan, you will have to be vigilant and rotate the trays more often. The leaves will dry before the blossoms. Once the leaves are brittle, remove their trays from the dehydrator and let them cool down completely.Once cooled, garble the leaves from the stems and put them into tightly capped glass jars such as mason jars (you will not be using the stems; they can be added to your compost pile).
It may take several more hours for the blossoms to completely dry. The petals will be dried before the base on the underside. Be patient and wait until the entire blossom is dry. When ready, remove the trays and allow the blossoms to cool down completely before putting them into the jars with the dried leaves. Store out of direct sunlight while the herb conditions.
Shake the jars daily to separate the pieces and also to check for moisture and mold. If condensation develops in a jar, return the calendula to the dehydrator.
After you have conditioned in this way for 7 to 10 days, you can pack the jars more tightly; store them in a cool, dry, dark location.