The genus Salvia, commonly known as sage, is one of the largest and most diverse groups in the plant kingdom, encompassing approximately 900 to 1,000 species of shrubs, herbaceous plants, and annuals within the mint family (Lamiaceae). These plants are valued for their aromatic foliage, medicinal properties, and vibrant ornamental blooms that attract pollinators. Whether a Salvia is a perennial or an annual depends entirely on the specific species and the local growing environment. Different types of sage have evolved in climates ranging from tropical jungles to arid deserts, resulting in varying degrees of cold tolerance and life spans.
Understanding Plant Life Cycles
To classify any plant, including Salvia, gardeners rely on four distinct life cycle categories.
An annual plant completes its entire life cycle—germination, growth, flowering, seed production, and death—within a single growing season, typically less than one year. These plants are grown for their season-long display of color and must be replanted annually.
A perennial plant lives for more than two years, returning from the same root system year after year. Herbaceous perennials die back in winter and regrow in spring, while woody perennials, like shrubs, maintain above-ground stems. A biennial plant requires two full years to complete its cycle, focusing on foliage growth in the first year before flowering and setting seed in the second year and then dying.
A fourth category, the tender perennial, is particularly relevant to the Salvia genus. This describes a plant that is genetically a perennial, capable of living for many years in its native, warm climate. When grown in regions with cold winters, however, it cannot survive low temperatures and must be treated as a seasonal annual.
Common Salvias Grown as Annuals
Many popular and brightly colored Salvias sold in garden centers are tender perennials that function as annuals in temperate climates. Salvia splendens, commonly known as Scarlet Sage, is a prime example, originally hailing from Brazil. This species is known for its dense, fiery scarlet flower spikes that provide consistent color until the first hard frost kills the plant.
Another widely used annual Salvia is Salvia farinacea, or Mealycup Sage, which produces spikes of true-blue, violet, or white flowers. While genetically a short-lived perennial hardy in USDA Zones 7 or 8 and warmer, its roots cannot withstand freezing temperatures in colder regions. Both S. splendens and S. farinacea grow quickly and flower profusely in their first year, so they are cultivated as seasonal bedding plants. Gardeners must replant them every spring for a continuous show of color.
Hardy Salvias That Return Yearly
The genus also includes many species that are reliably cold-hardy, returning each spring in temperate regions. These true perennial Salvias form the backbone of many mixed borders, surviving winter dormancy for multiple seasons.
One of the hardiest is Salvia nemorosa, often called Woodland Sage, which is reliably perennial in zones as cold as USDA Zone 3 or 4.
Salvia officinalis, or Common Garden Sage, is the culinary variety and is a woody perennial shrublet with silvery-green, aromatic leaves. This species is generally hardy in Zones 5 through 8 and is valued for its texture and flavor.
For gardeners in warmer temperate zones, Salvia greggii, or Autumn Sage, is a popular choice, typically hardy from Zone 6 or 7 through 9. This species is known for its shrubby habit and long-lasting display of flowers in shades of red, pink, or purple from spring until fall. These hardy varieties benefit from being cut back after flowering to encourage a second flush of blooms and maintain a tidy habit.
How Hardiness Zones Affect Salvia Classification
The distinction between a Salvia acting as an annual or a perennial is directly tied to the local climate, specifically the average minimum winter temperatures defined by the USDA Plant Hardiness Zone system. This system outlines geographical areas based on the lowest temperature a plant can survive. The same species of Salvia can behave differently depending on its zone.
For instance, Mealycup Sage (S. farinacea) is a true perennial in Zone 8, where winter lows rarely drop below 10°F. If a gardener plants that same variety in Zone 4, where winter temperatures routinely fall to -30°F, the plant will not survive and is classified as an annual for that location.
Gardeners must check the cold tolerance rating of the specific Salvia species against their own hardiness zone to determine if it will return yearly.