Morning glories are popular, fast-growing vining plants, known for their beautiful, trumpet-shaped flowers. Successful growth and abundant flowering depend significantly on understanding their temperature tolerance. This article explores the range of temperatures these plants can withstand, from optimal conditions to extreme cold and heat.
Optimal Temperature Range for Morning Glories
Morning glories thrive within a warm temperature range, typically between 68 to 95 degrees Fahrenheit (20 to 35 degrees Celsius). For optimal growth and prolific flowering, temperatures between 70 to 80 degrees Fahrenheit (21 to 27 degrees Celsius) are particularly conducive. These plants, with their tropical origins, benefit from consistent warmth.
Morning glory seeds germinate best when soil temperatures are consistently between 65 to 85 degrees Fahrenheit (18 to 29 degrees Celsius). This consistent warmth helps ensure robust seedling development and vigorous vine growth.
Morning Glories and Cold Temperatures
Morning glories are sensitive to cold temperatures, particularly frost. Most varieties are cultivated as annuals in temperate climates, meaning they complete their life cycle within one growing season and die back with the first hard frost. While they can tolerate temperatures dropping below 45 degrees Fahrenheit (7 degrees Celsius) for brief periods, prolonged cold or freezing conditions are detrimental.
When temperatures fall below freezing, morning glories show signs of damage. Leaves may first lighten in color, then progressively turn brown or black, often accompanied by wilting and drooping. Immature seeds on the vine can also be compromised by frost. For successful outdoor planting, it is best to wait until all danger of frost has passed and the soil temperature has warmed to at least 64-65 degrees Fahrenheit (18 degrees Celsius).
Morning Glories and Hot Temperatures
Morning glories are generally heat-loving plants and perform well in warm conditions. However, there are upper limits to their temperature tolerance. When temperatures consistently exceed 95 degrees Fahrenheit (35 degrees Celsius), the plants can experience stress. Some varieties might tolerate up to 105.8 degrees Fahrenheit (41 degrees Celsius), but signs of distress may appear.
Signs of heat stress include lighter leaves with dry or withered tips, indicating increased susceptibility to sunburn. Even with adequate moisture, wilting can occur, and the plant may exhibit reduced flowering or produce smaller blooms. Extreme and prolonged heat can negatively impact their health and flowering.
Protecting Morning Glories from Temperature Fluctuations
Protecting morning glories from temperature extremes involves proactive measures. For cold temperatures, plant seeds after the last frost date, when soil temperatures consistently reach 64-65 degrees Fahrenheit (18 degrees Celsius). Applying mulch around the base can help retain soil moisture and provide some insulation. In regions with early frosts, container-grown morning glories can be moved indoors to extend their growing season, ideally kept above 45 degrees Fahrenheit (7 degrees Celsius). For short cold snaps, covering vines with blankets or cloches offers temporary protection.
Addressing high temperatures focuses on moisture management and strategic shading. Consistent watering is essential, especially during dry, hot periods; plants typically need about one inch of water per week. Watering in the morning or evening helps maximize water absorption and reduces evaporation. In areas with prolonged summer heat, providing partial afternoon shade can prevent leaf scorching and reduce heat stress. While morning glories thrive in full sun, afternoon relief can maintain their vigor and bloom production.