Star Jasmine (Trachelospermum jasminoides) is a popular, fragrant vine known for its glossy evergreen foliage and intensely scented white flowers. Understanding its temperature tolerance is important for maintaining its health and promoting vigorous growth. While this plant shows adaptability across various climates, extreme temperatures, both cold and hot, necessitate specific care to ensure its survival and ornamental appeal.
Understanding Star Jasmine’s Temperature Range
Star Jasmine thrives within a specific temperature range, generally preferring environments between 60-75°F (15-24°C) for optimal growth and blooming. It is relatively cold-hardy, typically growing as a perennial in USDA hardiness zones 8-10, and sometimes in protected areas of zone 7. A more cold-tolerant variety, ‘Madison’, is hardy in zones 7-10.
Temperature tolerance refers to a plant’s ability to survive and function outside its ideal range. Star Jasmine can tolerate brief dips to temperatures as low as 10°F (-12°C), and some sources indicate it can withstand short periods down to 5°F (-15°C). However, prolonged exposure to temperatures below 59°F (15°C) in winter or above 100°F (38°C) in summer can cause stress or damage. The plant’s ability to tolerate these extremes is often influenced by factors like duration of exposure, plant maturity, and overall health.
Protecting Against Cold Temperatures
Frost and freezing temperatures can cause significant damage to Star Jasmine, leading to leaf discoloration and stem dieback. Young plants are particularly susceptible to cold winds and frost. If temperatures are expected to drop below 23°F (-5°C), protective measures become important.
For winter protection, apply a layer of mulch (straw, shredded hardwood, or leaves) around the base of the plant. This insulates roots and helps retain soil moisture. For prolonged cold snaps, covering the plant with frost cloth or burlap can shield it from harsh temperatures and drying winds.
Container-grown plants should be brought indoors to a bright, frost-free location where temperatures remain between 37-64°F (3-18°C). Ensuring the soil is adequately moist before a freeze can also help protect the roots. Choosing sheltered planting locations, such as near south-facing walls, can provide additional warmth and protection from cold winds. After cold damage, pruning affected parts in spring can aid recovery.
Caring for Star Jasmine in Heat
Star Jasmine exhibits good general heat tolerance and can thrive in warm climates. However, extreme or prolonged heat can still cause stress, particularly when temperatures exceed 86°F (30°C) or reach above 100°F (38°C). Symptoms of heat stress include wilting, reduced flowering, yellowing leaves, curled leaf tips, slowed growth, and sunburn (whitish or silver patches on the leaves).
Adequate watering is crucial during hot periods to prevent dehydration. Watering deeply helps establish a strong root system and keeps the soil moist. Applying a layer of mulch around the plant’s base helps retain soil moisture and keeps the roots cooler.
In regions with intense afternoon sun or during peak heat, providing partial shade can mitigate stress, either by planting location or using shade cloth. Fertilization should be avoided during extreme heat to prevent encouraging new, tender growth that could be damaged.