Dry your Sage in the oven at the lowest temperature by spreading out on baking trays lined with parchment paper in a single layer.
When dry (couple of hours) crumble the leaves, remove the stems, and save the leaves in an airtight container.
Note that by drying it in the oven, you may lose some of the aromatic oils that give it its flavour. You could freeze it. Rinse the sage in water, pat it dry, then chop it up and place it in small freezer bags. Frozen sage will have a more intense flavour than dried sage, since the aromatic oils won't have had a chance to evaporate.
Hello, I usually put the leaves in small bags in the freezer. The leaves will crumble when I come to use them. Return unwanted leaves to the freezer ready for use at a later date.