Lavender, known for its fragrance and beauty, is a popular choice for many gardens. While generally robust, its successful growth depends on understanding and managing its temperature requirements. Proper thermal conditions ensure a thriving plant with abundant blooms.
Understanding Lavender’s Ideal Temperature Range
Lavender flourishes within specific temperatures. Optimal daytime temperatures are 68 to 95°F (20-35°C), which encourages active growth and blooming. Soil temperatures above 65°F (18°C) also promote regeneration after harvesting.
The plant’s hardiness is described by USDA Plant Hardiness Zones, indicating average annual extreme minimum winter temperatures. Most lavender varieties are hardy in zones 5 through 9, tolerating lows of -20°F to -10°F (-29°C to -23°C). Some varieties exhibit greater cold tolerance, while others are more sensitive, requiring warmer conditions.
Lavender Varieties and Their Temperature Adaptations
Not all lavender varieties share the same temperature tolerance, so selection is important for specific climates. English lavender (Lavandula angustifolia), despite its name, originates from the Mediterranean and is a cold-hardy type, thriving in USDA Zones 5-9. Cultivars like ‘Munstead’ and ‘Hidcote Blue’ are resilient, surviving winter temperatures down to -10°F to -20°F (-23°C to -29°C). This variety also tolerates summer heat up to 95°F (35°C).
French lavender (Lavandula dentata) and Spanish lavender (Lavandula stoechas) are less cold-tolerant, hardy in USDA Zones 7-11 only. Spanish lavender thrives in hot, dry conditions and tolerates temperatures up to 90°F (32°C), but struggles below 10-15°F (-12°C to -9°C). French lavender is also heat-tolerant, favoring warm, dry climates but may not survive freezing temperatures. These varieties are better suited for warmer regions or for container growing where they can be moved indoors for winter. Lavandin hybrids (Lavandula x intermedia), like ‘Grosso’ and ‘Provence’, are hardy in zones 5-8 and prefer a temperature range of 41 to 95°F (5 to 35°C).
Protecting Lavender from Extreme Cold
Safeguarding lavender plants from harsh winter conditions is important in colder climates. Mulching provides insulation for the roots; a 2-3 inch layer of organic materials like wood chips, straw, or shredded bark applied after the ground freezes protects roots from freezing and thawing cycles. Keep mulch a few inches away from the plant’s crown to prevent moisture buildup and potential rot.
Wind protection is beneficial, as strong winter winds can dry out the plant. Placing lavender near a stone or brick wall offers warmth and protection. Creating a temporary barrier with burlap or frost cloth around the plants shields them from harsh winds while allowing air circulation. For container-grown lavender, moving pots to a sheltered location like a covered porch, an unheated garage, or indoors to a cool, bright room prevents cold damage.
Protecting Lavender from Extreme Heat
While lavender thrives in sunny, warm conditions, extreme heat can be challenging. During prolonged periods of high temperatures, particularly above 95-100°F (35-38°C), supplemental watering is important. Deep watering in the morning or evening helps the plant absorb moisture before the hottest part of the day.
Ensuring good air circulation around lavender plants benefits hot, humid environments to prevent fungal issues. While full sun is preferred, providing partial shade during the hottest part of the day, especially in climates with temperatures consistently exceeding 95°F (35°C), reduces heat stress. This is achieved with a shade cloth or by planting them where they receive afternoon shade.
Signs of Temperature Stress and Recovery
Lavender plants exhibit temperature stress. In cold conditions, symptoms include browning, wilting foliage, or stunted appearance. During recovery from cold stress, prune away any parts that failed to sprout new growth in spring.
Conversely, extreme heat causes leaves to lighten, curl, or scorch. Severe cases lead to wilting and drying. If observed, trim sunburned or dried parts and move the plant to a shadier location or provide temporary shade. Watering in the morning and evening helps keep the soil moist and supports recovery.