It all depends upon the material you are drying and the climate you are in. If you are in a dry location like Arizona, you live in a natural dehydrator. If you live if a moist place like me, a food dehydrator is required for drying some things. I have found it is impossible for me to dry these without a food dehydrator: parsley, basil, ragweed, chives, leeks, chilis, and I'm sure I'm forgetting others at the moment. It does make quicker work of roots like dandelion and dock. But there are others with I always lay on screens to dry, like lemon balm. I find the dehydrator on the lowest possible setting "bakes" the lemon balm and others too much.

So my suggestion, experiment. Try small amounts in different ways and see how well and fast they dry. See if you are happy with the results. Quick drying without "baking" your herbs is key to preserving their quality.

FataMorgana