Sage is a perennial. It lives through the winter down to temperatures of 12 degrees F and blossoms again in the spring. Every summer sage is harvested by twisting the leaves from a newly grown branch, as harvesting from the main stem slows down the growth of the plant. At the end of the summer, the plant is cut back. Protect the plant for the winter by only harvesting 1/3 of the top layer of leaves.
Once sufficient leaves have been harvested, soak them in lightly salted, cold water. This cleans the leaves and removes bugs that may have attached themselves to the leaves. Remove the leaves from the cold water and pat dry with a tea towel or paper towel. You can use a salad spinner to dry the leaves, but use it gently so the leaves do not break.
Since sage is tolerant to cold, it stores well in the refrigerator. Stack the leaves in a plastic container using a paper towel or parchment paper to separate the layers. This allows air to flow around the leaves. Close the lid tightly and store in the refrigerator. If you have harvested only a few leaves, you can use a plastic bag for storage.
Prepare the sage as you would for refrigeration, but it's not necessary to use the paper towels for layering. Ensure the leaves are completely dry before putting them into the containers. Seal the containers very tightly to prevent freezer burn. Sage can be frozen and still maintain its flavor for up to four months.
Like the herbs found in jars at the grocery store, sage can be dried for storage. Bunch several stems of the leaves together and tie them with kitchen string. Let them hang upside down in a cool, dry place for three weeks. You can also put cleaned sage into a gas oven for four days; the heat from the pilot light dries them. They still have their bright color and full flavor after drying. With either method, after drying, put the leaves in a glass jar and store.