How Many Minutes Does It Take to Dry Fresh Herbs in the Oven?

Fresh herbs are dried in about 1-2 hours at the oven's lowest setting (65-90°C / 150-195°F), with the door left slightly ajar. Whether the leaves are thin or thick determines which end of this range the time is closer to. The herbs are dry when the leaves crumble easily into powder when rubbed between your fingers; if they still bend, moisture remains. Why is the oven door left slightly open? Moisture that builds up in a closed oven slows the drying of herbs, and the leaves may look slightly blanched instead of drying. Propping the door open a few centimeters with a spoon handle allows moisture to escape and makes the time more predictable. At this oven temperature of 65-90°C / 150-195°F, thin-leaf herbs can generally dry within 1 hour using this method. Why does drying time differ between thin- and thick-leaf herbs? Thin-leaf herbs such as parsley and dill dry in 1-1.5 hours, while herbs with woodier stems such as thyme and rosemary can stay in the oven for up to 1.5-2 hours. Because mint leaves have a watery structure, they dry closer to the upper end of this range. Spread the herbs in a single layer without overlap when arranging them in the oven; herbs left in a thick layer will not dry evenly. What should you keep in mind before drying herbs? Wash the herbs thoroughly before placing them in the oven and remove most of the moisture with a paper towel; herbs left wet take noticeably longer to dry. For herbs with thick stems, drying is more even if you remove the leaves and discard the stems. Check the oven every 30 minutes, and if the edges of the herbs dry early, rotate the tray to help the whole tray dry evenly. What happens if herbs are over-dried? If the time is too long, the leaves not only dry out but also darken and lose flavor; the herbs become dark crumbs instead of powder. This can happen quickly, especially with thin-leaf herbs, in an oven that is not checked early. If dried herbs are placed in a jar before they have fully cooled after coming out of the oven, remaining moisture can condense and lead to mold; for this reason, they are recommended to rest at room temperature for at least 15-20 minutes before being put in a jar. Can herbs be air-dried instead of oven-dried? Herbs with woody stems, such as thyme and rosemary, can be tied in bundles and hung in a dark, well-ventilated place to dry on their own within 1-2 weeks; because this method does not use an oven, it preserves the aroma a little better. Juicy-leaf herbs such as parsley and dill are more prone to mold when air-dried, so they are not very suitable for this method. Although air-drying is slow, it uses no electricity, so it may be more practical than an oven when drying a large amount of herbs. What ratio of dried herbs should be used in place of fresh herbs? Because herbs lose water and their aroma becomes more concentrated during drying, dried herbs are generally used at about one-third the amount of their fresh form; for example, if a recipe calls for one 15 ml measure of fresh thyme, about one 4 ml measure of dried thyme is enough. This ratio is not an absolute rule; the aroma intensity may vary somewhat depending on how thoroughly the herbs were dried, including if drying was stopped a few minutes earlier or later.