The traditional way to preserve herbs is by air drying or using low heat. Drying concentrates the flavor of herbs so you may need to only use one-third to one-fourth the amount of fresh herbs in recipes.

The process

After harvesting, gently wash the herbs and dry them thoroughly on paper towels. Remove any dead or damaged material. Tie the herbs in loose bunches that allow for good air circulation around each bunch. The bunches could be put into small paper bags with the stem ends sticking out of the top of the bag. Punch holes in the bag to allow for ventilation. The bags help protect the herbs from dust and other contamination while drying. Hang the herb bunches in a warm, dry, well-ventilated area out of the sun. A garage, shed, barn or well ventilated attic work well. It may take up to a month for herbs to dry completely.

• Tray drying is another method that works well with short stemmed herbs or for individual leaves.  A simple frame that has screen wire fastened to the bottom works well.  Put herbs in a single layer across the bottom and place the trays in a warm, well-ventilated area out of the sun.  Leaves may need to be turned to insure even drying.
• Drying with heat can involve the use of conventional ovens, micro-wave ovens or dehydrating ovens.
• Home food dehydrators do an excellent job of drying herbs.  Refer to the owner’s manual for specifics and settings.
• Oven drying works well if the temperatures can be closely monitored.  Oftentimes, oven temperatures cannot be set low enough and the result is loss of flavor and color.  However, if oven temperatures can be held between 90 and 110 degrees that would be the ideal oven drying temperature.  Setting your oven at the lowest temperature and leaving the oven door slightly open often results in temperatures that can be maintained at that level. Check the progress of drying often and turn the herbs if necessary. It may take 3-4 hours to dry herbs using this method.  
• Microwave ovens can also be used to dry small quantities of herbs quickly. Always observe safety precautions when drying herbs in a microwave and check manufacture's recommendations for using their product when drying herbs as the risk of scorching herbs and the possibility of starting fires exists. Prepare herbs by washing and drying very thoroughly. Any excess moisture on herbs leads to them cooking and not drying. Place herbs between two pieces of paper towel and microwave on high for 1-3 minutes. Check the progress every 30 seconds and turn the herbs to insure even drying. After removing from the microwave place herbs on a rack and allow them to cool before storing. 

After herbs are dry remove the leaves from the stems and package in sealed containers in a cool location, out of sunlight. To preserve the full flavor of herbs try to avoid crushing the leaves when packaging. Ideally herbs should be crushed just prior to adding them to recipes. With proper storage, most herbs retain their flavor for about a year. 

Try drying herb seeds

Cut stems with seed heads just as the heads begin to turn brown. Gather them into small bunches and hang the bunches upside down in paper bags that have ventilation holes punched in the sides of the bags. Hang the bags in a warm, well-ventilated area out of the sun to dry. Once dry, the seeds can be shaken from the seed heads. Carefully rub the seeds to separate seed from the capsules. Laying the seeds on a clean flat surface and gently blowing across the seeds will help remove any debris and chaff. Collect the seeds and store in sealed containers. Seeds may take longer to dry than leaves. Make sure the seeds are thoroughly dry before storing to avoid the possibility of the seeds becoming moldy.

Freezing

While freezing herbs is perhaps the easiest method, herbs handled this way are most useful used in the cooking process, as frozen herbs are not suitable for garnish.  Freezing will alter the appearance quality but not the flavor quality. After herbs are washed, they can be coarsely chopped and generous pinches of herbs can be placed in water filled ice cube trays and frozen. The cubes can then be transferred to plastic bags and placed in the freezer.  Individual cubes can be taken out as needed. Herb leaves can also be blanched in boiling water for about one minute and then quickly cooled by plunging them into ice water. The leaves can then be put into tightly seal plastic bags and frozen.