You CAN dry dill in a dehydrator.
If you are pressed for time, a food dehydrator is a fast and efficient method of drying dill. The disadvantage to using a dehydrator on herbs rather than allowing them to air-dry naturally is that they will lose some of their flavor during the process.
How to Dry Dill in a Dehydrator
As the dehydrator method is already the quick route to drying your dill, set your dehydrator on the lowest setting to allow the herb to dry more slowly. Don't try to hasten the process by cramming dill bunches one on top of another. In order for it to dry consistently, place individual sprigs on your tray in a single layer. This method can take several hours to a full day to process.
Be available to check on the drying process every several hours. The dill will be completely dry when it crumbles easily.
Harvest Timing Is Essential to Dry Herb Quality
To preserve as much of the fresh dill flavor as possible, the main objective is to harvest it while its essential oils are at their most pungent. During the day the plant's essential oils evaporate. The oils will replenish overnight so the best time to harvest would be early in the morning.
Dry Dill Shelf Life
Your dry dill should retain its flavor for up to one year if you store it in an airtight container away from humidity and light. The more it is exposed to the elements the faster it will degrade and lose its flavor.