Many varieties of thyme have been bred to work as groundcovers rather than as culinary herbs, so look for Thymus vularis, also sold as common thyme, if you’re after flavor. The citrusy T. citriodorus ‘Aureus’ is another good choice. Both are hardy to about -15F. They prefer sun but will tolerate light shade, and don’t require much water or rich soil. The tiny leaves of thyme can be stripped off the stem, but in a cocktail, you’re better off just throwing the whole sprig in the shaker. Add thyme to any cocktail that calls for grapefruit–they’re perfect together.