Yes, from a botanical perspective, rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) is classified as a perennial plant. This means it is a woody plant that has a life cycle spanning more than two years, designed to regrow from its root system each spring to flower and set seed repeatedly throughout its lifetime.
Rosemary is an evergreen woody perennial shrub. Its stems lignify, meaning they develop a hard, woody texture, which provides the structural strength necessary for the plant to survive for many years. Unlike annuals, which complete their entire life cycle in one season and die, or biennials which take two years, a perennial like rosemary invests energy in establishing a robust root system and framework that allows it to persist and produce new, softer herbaceous growth each year from the established woody base.
The lifecycle begins with seed germination, a process that can be slow and erratic for rosemary. Once established, the plant enters a prolonged vegetative stage, producing its characteristic aromatic, needle-like leaves. As a perennial, it will not typically flower in its first year. Upon reaching maturity, which can be in its second or third year, it enters a recurring reproductive phase. It produces small blue, purple, pink, or white flowers, which are highly attractive to pollinators. After pollination, it sets seed, but it also continues to vegetatively expand its woody structure. This cycle of flowering and seed production repeats annually for the remainder of the plant's life.
While rosemary is genetically a perennial, its ability to express this perennial nature outdoors is entirely dependent on climate, specifically winter temperatures. In the United States, the plant is winter-hardy perennially in USDA Plant Hardiness Zones 7 through 10. In these zones, winter minimum temperatures typically do not fall below 0°F to 10°F (-18°C to -12°C), allowing the plant's woody structures and root system to survive the dormant winter season. In these favorable climates, a rosemary plant can live for a decade or more, often becoming a large, sprawling shrub.
In regions colder than Zone 7 (e.g., Zones 6 and below), rosemary behaves as a tender perennial. Its tissues are not cold-hardy enough to survive freezing temperatures and prolonged ground frost, which will kill the woody stems and roots. In these areas, the plant is often grown as an annual for one season or must be provided significant winter protection, such as heavy mulching, or be grown in containers that can be brought indoors to a cool, bright location to survive the winter. In this scenario, it is the environmental conditions, not the plant's innate genetics, that prevent it from fulfilling its perennial lifecycle.
