Lavender is a favored garden addition, known for its fragrance and beauty. Successful cultivation requires understanding its temperature preferences for optimal health and flowering.
Optimal Temperature for Growth
Lavender thrives in warm, moderately dry climates, mimicking its Mediterranean origins. An ideal daytime temperature range for active growth and flowering is 68°F to 86°F (20-30°C). Consistent temperatures within this range during spring and early summer encourage robust development and prolific blooming. Soil temperatures above 65°F (18°C) also promote vigorous growth and regeneration after harvesting.
These moderate temperatures allow the plant to efficiently photosynthesize and direct energy towards flower and essential oil production. High humidity can hinder growth and increase susceptibility to fungal diseases. Extreme heat during summer can also negatively affect the quality of floral stems and essential oils.
Lavender’s Cold Tolerance and Winter Care
Lavender exhibits resilience to cold, with many varieties, especially English Lavender (Lavandula angustifolia), hardy down to USDA Zones 5-9. Some cultivars can survive in USDA Zone 3 or 4 with protection. During winter, lavender enters dormancy, its leaves changing to a silvery-sage hue. This period allows the plant to conserve energy for new spring growth.
To protect lavender from freezing temperatures, especially in colder zones, apply a 2-3 inch layer of mulch, such as wood chips, fallen leaves, or straw, to insulate the roots. Keep this mulch a few inches away from the plant’s crown to prevent moisture buildup and rot. For container-grown lavender, move pots to a sheltered location like an unheated garage or covered patio, where temperatures remain consistently above freezing (35-45°F or 2-7°C). In very cold climates (Zone 5 and below), covering plants with burlap or frost cloth during extreme weather shields them from harsh winds and prolonged freezes.
Lavender’s Heat Tolerance and Summer Care
Lavender is well-adapted to warm, dry conditions and full sun exposure, requiring at least 6-8 hours of direct sunlight daily. It prefers dry, well-draining soil and dislikes “wet feet,” especially in hot weather. Overwatering is a common issue that can lead to root rot, particularly when coupled with heat.
During hot spells, established lavender plants are drought-tolerant due to their deep root systems. Newly planted lavender requires regular watering to establish itself. For mature plants, water deeply but infrequently, allowing the soil to dry out completely between waterings.
Good air circulation around plants helps prevent fungal issues in warm, potentially humid conditions. Planting in sandy or gravelly soil, or amending heavy clay soil with grit, improves drainage and helps lavender thrive in heat. Some varieties, like Spanish Lavender (Lavandula stoechas) and French Lavender (Lavandula dentata), are well-suited for hot climates.