Rinse the plums under cool water to remove any dirt or debris.
Slice the plums in half, and carefully remove the pits from each plum using a sharp knife or a pitter.
Depending on the size of your plums, you can keep them in halves or slice into pieces about ¼ to ½ inch thick for optimal drying.
Once the plum slices are ready, you can choose to pre-treat them to prevent browning by dipping in lemon juice. While it's not necessary, pre-treating will help maintain the vibrant color of the plums. I usually skip this step.
Arrange the slices in a single layer on the dehydrator trays or a baking sheet lined with parchment paper. Make sure to leave some space between the slices to allow for proper air circulation.
If using a dehydrator, set the temperature to around 135°F to 140°F (57°C to 60°C) and let the plums dry for approximately 8 to 24 hours.
You'll know the plums are fully dehydrated when they are pliable with no visible moisture. They may feel slightly sticky to the touch, but not moist.
To test their readiness, simply take a slice and let it cool for a few minutes. If it feels dry and leathery, your plums are ready for storage.