Drying Basil, Oregano and Rosemary
Answered by: Conrad Richter
Question from: Pat Cabana
Posted on: August 3, 1998

I have a lot of basil, oregano and rosemary growing in my garden. How can I dry these herbs to have all year?

It is often recommended that herbs be picked just as the herbs begin to flower. This is the optimum time when the eseential oils that give the herbs their characteristic flavour and aroma are at their maximum levels. However, rosemary is not likely to be in bloom in your garden if you are in the temperate climate zone, so you will pick it when not blooming. Even basil and oregano are quite alright to pick when not blooming as you will know anytime you squeeze a leaf and smell the burst of aroma.

It is also suggested that herbs be picked in the late morning on a sunny day, after the dew has evaporated and before the hot sun drives out the essential oils.

The trick to drying herbs is to get the water out without losing the essential oils. But the essential oils are more volatile (escape into the air) more easily than water, which presents the challenge. Fortunately, it is relatively easy to dry herbs as long as you remember that essential oils can escape if you are not careful.

We like to strip the leaves off the stems before drying. This cuts off the source of water from the stems and promotes faster drying. We like to lay the leaves on a screen. The screen is elevated so that there is ventilation above and below the herbs. The herbs should not be too crowded that the leaves overlap while drying. Any warm, dry, well-ventilated and shaded location will work. Sun can cause herbs to fade, and too much humidity can slow drying to the point that the herbs become mouldy.

Applying heat is useful but you must take care not to turn the heat up too high. High heat (over 35 degrees Celsius or 90 degrees Fahrenheit) will expel the water quickly – which is good – but it will also expell the essential oils leaving you will tasteless herbs. Drying in the oven has to be done very carefully; set the temperature at the lowest setting and leave the door ajar. If your oven is too hot your house will smell great but your herbs will be insipid. Some people have success using a microwave, but we find that the results are often inconsistent and the quality is poor.

Herbs must be dried to completion before storing. If the herbs feel leathery instead of crisp then they are not ready and will go mouldy if stored in this condition. If the leaves crumble easily when squeezed then they are ready. Finishing off herbs in an oven is a good idea to make sure that there is no excess moisture present in the leaves that would promote moulds from growing.

Herbs should not be powdered before storage; you should crumble herbs just prior to use. The reason is that whole herbs lock in the essential oils better than powdered herbs. Store herbs in airtight containers keep in a cool, dry, dark location.

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