Arp rosemary (Rosmarinus officinalis Arp) is an old favorite with two important characteristics that distinguish it from ordinary rosemary. First, it has a unique, upright growth habit so that it's always neat and second, it's more cold tolerant. There are even accounts of it overwintering successfully in zone 6 with a little protection. Evergreen and deliciously fragrant, rosemary is a great addition to cookery as well making a great hair rinse that makes dark hair extra glossy. And of course, you'll love the sky-blue flowers and the gorgeous evergreen foliage.