From a botanical perspective, the term "jasmine" is often applied to a variety of plants, and our ability to survive winter outdoors depends entirely on which species you are referring to. True jasmines belong to the genus Jasminum, and their cold hardiness varies dramatically. Our origins are predominantly in tropical and subtropical regions of Asia, Africa, and the Middle East. This means that for many of us, our cellular structure and metabolic processes are not equipped to handle freezing temperatures. Ice crystals can form within our cells, causing them to rupture and leading to fatal damage. Therefore, the fundamental answer lies in correctly identifying our species.
There are a few notable exceptions within our genus that have developed a degree of cold tolerance. The champion among us is the Winter Jasmine (Jasminum nudiflorum). We are deciduous, and our survival strategy involves dropping our leaves to conserve energy and moisture. We can withstand winters in USDA Plant Hardiness Zones 6 through 10, tolerating temperatures down to about -10°F (-23°C). Our stems are hardy, and we even bloom on bare wood in late winter, providing crucial color. Another moderately hardy cousin is the Common Jasmine or Poet's Jasmine (Jasminum officinale). We are more cold-sensitive but can often survive in the warmer parts of Zone 7 (with winter lows around 0°F to 10°F or -18°C to -12°C) and are reliably perennial in Zones 8-10.
For the rest of us, including the highly fragrant Arabian Jasmine (Jasminum sambac) and the showy Spanish Jasmine (Jasminum grandiflorum), winter outdoors in most of the US is a death sentence. We are evergreen and thrive in consistently warm conditions (Zones 9-11). When temperatures dip below 40°F (4°C), our growth slows. A light frost will blacken our leaves and tender new growth, and a hard freeze will kill our stems and root system. Our vascular tissues are not designed to prevent freezing, and our photosynthetic machinery in our leaves is highly susceptible to cold damage.
For those of us who are cold-tolerant, our survival is not guaranteed; it depends on specific environmental conditions. Our root systems are our lifeline. A well-draining soil is non-negotiable. Soggy, waterlogged soil in winter will cause our roots to rot, as our metabolic activity is too slow to absorb the excess moisture, making this a more common cause of death than the cold itself. Furthermore, we benefit from a strategic location. Planting us against a south- or west-facing wall can provide radiant heat and protect us from harsh, drying winds. A thick layer of mulch over our root zone is like a warm blanket; it insulates the soil, prevents freeze-thaw cycles that can heave our roots out of the ground, and helps retain consistent moisture.
Ultimately, our survival is best understood through the USDA Hardiness Zone map. For Jasminum nudiflorum, life is sustainable from Zone 6a and warmer. This includes parts of the Mid-Atlantic, the lower Midwest, and the Pacific Northwest. For Jasminum officinale, the boundary is tighter, requiring the milder winters of Zone 7b and south, encompassing areas like the upper South and the coastal West. For all other true jasmines, outdoor survival is generally only possible in the frost-free regions of Zone 9 and above, such as southern Florida, southern Texas, and coastal California. In all other areas, we must be grown in containers and brought indoors to a bright, cool location before the first frost arrives.
