It's actually not all that hard to dry herbs in the oven. Depending on what type of oven you have, you should have to supervise the drying. You might even be able to just pop it in there and forget about it till morning!
The first few steps are the same for any type of oven. Pick your herbs early in the morning when their oil content is the highest. This gives the best flavor. Rinse the dirt off your herbs and pat lightly with a lint free towel to dry. Remove any damaged, brown or withered leaves. Cut a piece of parchment paper the size of your baking sheet and use it to line the baking sheet. Arrange your herbs on the baking sheet. Leave room between sprigs (don't pull leaves off the stems yet, It'll be much easier later!) Spread out flowers, sprigs or cut chives leaving room for air circulation. Stick that bad boy in the oven and choose your oven method below.
Gas oven with interior pilot light: When I had one of these it was always warm and dry in there. I could simply put the herbs in and shut the door then leave it overnight. Even though the oven was off they were always perfectly dry by morning.
Oven with convection feature: This is the one I currently use. I turn the oven on 170 and convect. Leave herbs for about 20 minutes then turn, flip, toss.....whichever, just get them flipped over so the part that was on the baking sheet is now in the air. Let it convect for about 20 more minutes then turn oven off. Check for even dryness. If not, stir flip or turn again and place back in oven for 20 more minutes. When done turn oven off and leave in warm oven till cool.
Regular oven (no convect, no interior pilot light): This is the trickiest since there is no air flow and you'll be using high temperatures. Set oven to 170. You'll need a wooden spoon to prop the oven door open just a bit to help with airflow. This will take longer then a convection oven. I stir, toss or flip the herbs about every 20 minutes. The opening and closing of the oven adds some airflow and lets some of the moist air out of the oven. It will probably take close to 2 hours to completely dry your herbs. Keep checking and flipping every 20 minutes. When done just turn oven off and leave till cool.
Once dry you can strip the leaves from the stems of most herbs by running your fingers down the stems. They should pull right off. Crumble one between your fingers. If it turns to powder, they're done. If they are still a little soft then they'll need more drying time. Once completely dry I store them in clean dry mason jars. (ok...recycled pasta sauce jars, they look the same!) I leave the lid off the jar for the first day or 2 just to keep them exposed to air a little longer. If you live in a humid area, I would skip this step and put the lids on right away.
Things to consider:
- If the herbs were still a bit wet when placed in the oven they will need a longer time to dry.
- Some herbs have more oils then others. The more oil content they have, the longer they will take to dry.
- Drying several types of herbs in the same oven at the same time makes sense, but more pungent herbs might lend their flavors to more delicate herbs. For instance I wont dry my chamomile with the oregano or chives ever again!
- When drying several types of herbs at once some will be done sooner then others, remove them as soon as they're dry and let the pans sit on top of the oven to cool.
- Use a separate lined baking tray for each herb unless you really do want them mixed when they're finished. Picking dill out of your sage is no fun!
- Never use a temperature over 200! It will bake the herbs not dry them causing many types to blacken and lose all flavor.
- If your oven does not go as low as 170 you can put the herbs in and turn it on and get it as close to 170 as possible. Then turn it off and let it slowly cool down to room temperature. Toss the herbs around to see if they're thoroughly dry. If not repeat the process, turning each time the oven cools down until dry.
- The faster the herbs dry, the better the flavor will be. Even if you do have that first oven with pilot light...if you have the time you might want to try the other methods instead.