Roots won't dry well if at all in the sixties. I have lots of trouble drying roots in the fall because of cool conditions. I actually dehydrate a lot of my roots in a unit I built. I use an old up right freezer with compartment doors on it and one main door. I built drying racks in it so I could use a 75 to 100 watt light bulb to put warm air in the unit. I put my bulb in the very bottom of the freezer and clsoe all the compartment doors and close the main freezer door to where it has about an inch crack in the door. This lets humidity out of the unit.
Now if I have larger amts. of roots to dry , say 30 -40 lbs of roots , I either put them on screens in a wooden outbuilding that is a 10x16 and close the doors and turn on a fan. Or I put them on tarps outside and let them be in kind of a little shade and a little sun. If you do it that away, be sure to never let it rain on your roots and be sure and bring your roots in at the end of the day. Dew will make your roots look bad.
Never dry your roots in a microwave nor a conventional oven on your stove. To have success you pretty much have got to follow my steps fairly close, unless your lucky.
Always something to worry with , is that not right? Just like fur, ifin you don't know how to do the process, you can sure mess up a bunch of money.
You can also use wood heat in a building and put air on your roots. Have the roots on racks with the air circulating through the building. I like the temps to be no less than 80 and no hotter than 100 and even at 100 it is a little warm. Actually I think best conditions are from about 85 to 95.
Roots won't dry well in a damp basement or a cool basement.