Chamomile, a popular herb known for its delicate, daisy-like flowers and calming properties, is widely used in herbal teas and medicinal applications. For gardeners, understanding temperature’s role in its cultivation is crucial for healthy, productive plants. Temperature influences chamomile from seed sprouting to the development of its aromatic qualities.
Optimal Temperatures for Chamomile Growth
Chamomile thrives within specific temperature ranges throughout its life cycle, contributing to its overall vigor and bloom production. For successful seed germination, soil temperatures between 59°F and 85°F (15°C and 29°C) are optimal, with 65°F (18.3°C) often cited as ideal. Germination can begin within 3 to 5 days if temperatures are between 63°F and 80°F (17°C and 27°C).
Once past germination, chamomile prefers moderate air temperatures for robust vegetative growth. A daytime range of 60°F to 68°F (15°C to 20°C) is ideal for active growth, supporting lush foliage and strong stems. For flowering, continuous optimal temperatures, often within 60°F to 70°F (15.5°C to 21°C), encourage abundant blooms. Maintaining these conditions ensures a prolonged flowering period and a higher yield.
Chamomile’s Tolerance to Temperature Extremes
Chamomile exhibits resilience to temperatures outside its optimal range, though prolonged exposure to extremes impacts its health. Roman chamomile, a perennial, is hardy and can survive winters in USDA zones as low as 4, tolerating subzero climates. Young seedlings withstand light frosts. However, heavy freezes or prolonged cold can be detrimental, especially for German chamomile (an annual). Signs of cold stress include decreased or no sprouting if temperatures fall significantly below freezing.
Chamomile tolerates higher temperatures, thriving in summer weather up to 100°F (38°C). However, sustained heatwaves or temperatures consistently above 70°F (21°C) can cause heat stress. Symptoms include wilting, reduced flowering, and a general decline in plant vigor. In hot climates, partial shade during the hottest parts of the day helps mitigate these effects and prevents bloom burning.
How Temperature Influences Chamomile Qualities
Temperature significantly shapes chamomile quality, particularly its beneficial compounds and flavor. Temperature affects the concentration and composition of essential oils like chamazulene and bisabolol, which contribute to chamomile’s aroma and medicinal value. Studies suggest temperatures around 68°F (20°C) lead to the highest chamazulene content. While low temperatures can increase essential oil percentage and yield, high temperatures decrease plant characteristics and essential oil content.
Temperature also influences the overall yield and flavor profile of chamomile flowers. Sustained optimal temperatures lead to a longer flowering period and a higher yield of usable flowers. Conversely, temperature stress can impact flavor, potentially leading to a more bitter taste, especially in Roman chamomile. Maintaining suitable temperatures supports both plant growth and the desired characteristics of harvested chamomile.
Managing Chamomile Temperature for Success
Strategic temperature management is important for cultivating healthy chamomile. Proper site selection is a primary step; chamomile benefits from full sun for optimal flowering, but in hotter climates, partial afternoon shade protects plants from intense heat. Adequate air circulation also prevents issues like powdery mildew, which can arise in humid conditions.
Planting time should align with local temperature patterns to ensure seedlings establish during favorable conditions. In regions with cold winters, start seeds indoors 4-6 weeks before the last frost for transplanting outdoors when frost risk has passed. For outdoor sowing, wait until mid-spring when soil temperatures are warmer.
Mulching with materials like chopped leaves or straw helps regulate soil temperature, keeping roots cooler in summer and providing insulation during cold snaps. Row covers or frost blankets offer additional protection for young plants from early cold spells. Consistent watering, especially during dry periods or heat, helps plants cope with temperature fluctuations by keeping the soil moist.