Rosemary is a beloved herb, recognized by its fragrant, needle-like leaves and attractive blue flowers. When searching for varieties, many people wonder exactly how many types exist. The answer is complex because the variations available are not separate species but rather forms of a single plant. The botanical classification of rosemary has recently been updated, adding a layer of complexity to understanding its forms.
The Botanical Reality: One Species, Many Cultivars
Rosemary was traditionally known by the scientific name Rosmarinus officinalis, which translates to “dew of the sea.” This referred to the singular species native to the Mediterranean region. Recent genetic research confirmed that rosemary belongs within the larger Salvia genus, which includes true sages. This reclassification means that botanically, the vast majority of rosemary is considered one species, now formally known as Salvia rosmarinus.
The numerous forms seen in gardens are classified as cultivars, which stands for “cultivated varieties.” A cultivar is a plant selected and bred by humans for a specific desirable trait, such as flower color, cold tolerance, or growth habit. These variations all share the same species DNA but display unique characteristics that make them distinct for gardeners and chefs. This distinction explains why there is no fixed count of rosemary types; new cultivars are continuously being developed.
Defining Types by Growth Habit
The most practical way to categorize the different rosemary cultivars is by their natural growth pattern. These habits primarily determine how a rosemary plant should be used in a landscape or garden. The two main forms are the upright varieties and the trailing, or prostrate, varieties.
Upright rosemary cultivars form sturdy, erect shrubs that can grow quite tall, sometimes reaching six feet or more. This structure makes them suitable for use as fragrant hedges, screens, or formal topiary shapes. The vertical growth habit also allows for easier harvesting.
In contrast, trailing or prostrate types have flexible stems that spread low along the ground or cascade over edges. These varieties are often used as groundcover, especially in sunny, dry areas, or planted in containers to spill over the sides. These spreading forms are typically less vigorous than their upright counterparts.
Essential Cultivars for Home Use
‘Arp’ is one of the most frequently recommended cultivars because it is known for its exceptional cold tolerance, surviving temperatures as low as -10°F in USDA Zone 6. This upright variety features grayish-green foliage and an open, bushy growth habit, making it resilient in cooler climates.
Another popular choice is ‘Tuscan Blue’, a vigorous cultivar with a dense, upright form that can reach up to six feet in height. Prized for its deep, intense blue flowers and highly aromatic, dark green leaves, it is a favorite for culinary applications and formal hedging. Its robust structure and striking appearance make it a common landscape feature.
For those needing a sprawling variety, the ‘Prostratus’ cultivar is a low-growing, creeping form ideal for cascading over walls or filling in rocky terrain. It typically remains under a foot tall but can spread several feet wide, providing a fragrant groundcover.
‘Spice Islands’ is an upright cultivar selected for its culinary excellence, offering a clean, citrusy, and highly potent flavor. Its long internodes make the leaves easy to strip from the stem for cooking and drying. ‘Miss Jessup’s Upright’ is valued for its distinctly vertical and columnar growth habit, which is naturally neat and compact. This variety is an excellent option for gardeners with limited space.