Rosemary is one of the largest of the culinary herbs, growing into a shrub about 1-1.2 m in height. Hailing from the Mediterranean, it requires sun, good drainage and a dryish soil to do well. It has pale blue flowers in spring. Its leaves are fine, aromatic needles and it has plenty of uses in the kitchen, having a particular affinity with lamb. It is often used in Italian cooking with roasted potatoes, focaccia and olives, for example. The shrub can get a bit leggy so regular light pruning (particularly after flowering) will keep it looking shapely, rather than a savage pruning once in a blue moon: from which it may not recover! It can be used to form a low hedge or grown as a small standardised plant. It can be grown in a container - especially the more compact varieties.
There are a number of different named cultivars of Rosmarinus officinalis, including the dark blue-flowered 'Tuscan Blue', white-flowered and pink-flowered cultivars, and one with yellow-marked foliage. There are also low-growing types, such as the cultivar 'Prostratus', useful for compact places or on top of walls. The upright cultivar 'Mozart' is said to have very deep blue flowers (ht 70 cm). Propagation is via cuttings taken in spring or autumn. I have also found they can strike roots in a glass of water on a windowsill in late summer! Old plants may decline after about 10 years but it is worth cutting them back by half in spring to try to rejuvenate them. Rosemary belongs to the Lamiaceae family of plants and is frost hardy.
Good companions for rosemary are some of the other sun-loving Mediterranean plants that do well in Sydney's climate: lavender, marguerite daisies, perennial wallflowers, perennial statice and tall bearded irises, as well as other robust perennial herbs such as thyme, sage and oregano. Rosemary also looks good with succulents growing nearby, which provide a foliage contrast to its needled texture.