Lavender is a highly sought-after perennial, cherished for its intense fragrance and striking purple blooms. Native to the arid Mediterranean, this herb tolerates heat and dry conditions once established. While gardeners seek to replicate these native conditions, the plant’s ability to survive cold winter months is the primary factor determining success. Understanding the appropriate growing zone is the first step toward successfully cultivating this aromatic subshrub. The hardiness zone designation guides selecting a variety that can withstand the lowest temperatures of a specific region.
Deciphering the USDA Plant Hardiness Zone Map
The United States Department of Agriculture (USDA) Plant Hardiness Zone Map is the standard tool for determining if a perennial plant will survive in a given location. This map divides North America into distinct zones based on the average annual extreme minimum winter temperature. Each numbered zone represents a 10-degree Fahrenheit difference, indicating progressively warmer winter lows.
For increased precision, each zone is divided into ‘a’ and ‘b’ subzones, representing a finer 5-degree increment. Gardeners use this system to match the cold tolerance of a plant to their local zone number. If a plant is rated for Zones 5 through 9, it is expected to survive the coldest winter temperatures in Zone 5 but not in the colder Zone 4.
Hardiness Zones for Popular Lavender Types
The hardiness zone for lavender depends on the specific species and cultivar being grown. English Lavender (Lavandula angustifolia) is the most cold-tolerant species, thriving across USDA Zones 5 to 9. Cultivars like ‘Munstead’ and ‘Hidcote’ are recognized for their robust cold resistance, often surviving temperatures as low as -20°F in Zone 5. Gardeners in the cooler parts of Zone 4 can sometimes grow these varieties successfully with added winter protection.
Lavandin (Lavandula x intermedia) is a hybrid that generally exhibits a slightly narrower cold tolerance range than English varieties. This group, including popular cultivars like ‘Grosso’ and ‘Provence,’ is reliably perennial in Zones 6 through 9. Some hybrids, such as ‘Phenomenal,’ demonstrate hardiness extending down into Zone 5, making them suitable for regions with moderate winters. Lavandin plants tend to be larger and produce a more camphor-heavy fragrance.
Spanish Lavender (Lavandula stoechas) is the most tender cultivated type, requiring significantly warmer conditions to survive. This species is generally only hardy in the milder climates of USDA Zones 7 through 10. In these zones, the plant tolerates minimum temperatures down to 0°F to 10°F. Spanish lavender will not survive the deep freezes of colder regions and is often grown as an annual or overwintered indoors in zones colder than Zone 7.
Local Variables That Affect Lavender Survival
While the USDA zone provides a reliable guideline, local conditions significantly influence lavender’s ability to survive. The most important factor is the quality of soil drainage. Lavender is intolerant of “wet feet,” and poor drainage often kills the plant more frequently than extreme cold.
The soil must be well-aerated and fast-draining, ideally amended with grit, coarse sand, or gravel to prevent waterlogging around the root crown. Lavender prefers a lean soil that is not overly rich in nutrients, with a neutral to slightly alkaline pH (6.8 to 7.5). Soil that is too fertile or holds too much moisture will cause the roots to rot, especially during the dormant winter season.
Microclimates within a yard can effectively shift the survival zone for lavender. A sheltered location, such as a raised bed against a south-facing wall, can provide enough reflected heat to move the site into a warmer half-zone. For gardeners in marginal zones (like Zone 5), applying a thick, loose layer of mulch (straw or pine needles) after the ground freezes helps insulate the crown and protect the plant from damaging freeze-thaw cycles.