What Is the Minimum Temperature for Star Jasmine?

Outdoors

• The star jasmine is an evergreen plant that can reach a height of 20 to 40 feet when grown under ideal conditions, although many plants are only about 6 feet high. Although a member of a different genus than other plants called jasmine, the star jasmine has exceptionally fragrant, five-petaled white flowers that cover its vines in May and June. The coldest portion of its normal range, USDA zone 8, has winters with temperatures as low as 10 or 15 degrees Fahrenheit. Star jasmine can withstand these low temperatures for periods of time, although it may lose some leaves or young shoots when extreme cold lasts for more than a few days.

Protection

• Choosing the best site for a star jasmine plant can help it survive cold spells. For example, siting it against a warm, west- or south-facing wall of a building can help protect it from freezing air. Planting a jasmine on a hillside, where cold air drains away to lower portions of the slope, can also help lessen the risk of damage caused by cold. Cycles of freezing and thawing during winter can leave a jasmine plant partially out of the ground, but adding a thick layer of mulch in fall shades its roots, preventing thawing on warm days and minimizing this problem.

Extra-Hardy Types

• One cultivar of star jasmine called "Madison" (Trachelospermum jasminoides "Madison") is extra-hardy. A 5- to 10-foot-tall plant that blooms in spring, earlier than most varieties, it grows in zones 7 through 11. Another species called Asian star jasmine (Trachelospermum asiaticum) is also hardier than the common type. The cultivar called "Red Top" (Trachelospermum asiaticum "Red Top") has leaves that are red when young, while leaves on "Shirofu Chirimin" (Trachelospermum asiaticum "Shirofu Chirimin") are marbled pink, white and green on a short, 3-foot-tall plant. Asian varieties grow in USDA zones 7 through 11.

Growing Indoors

• Star jasmine does well in a container, either potted with a trellis or other support, or allowed to cascade over the edge of a hanging pot or basket. You can grow a potted jasmine outdoors during the warm months of spring, summer and early fall, moving it indoors to a bright spot near a south- or west-facing window when temperatures drop below freezing. Indoor temperatures of 50 to 55 degrees at night and 68 to 72 degrees during the day are ideal. In spring, after danger of frost has passed, you can move the plant outdoors. To prevent scorching of its leaves and new growth, expose the plant to sunlight gradually, adding an hour or two of sun each day.