From our perspective as plants, the answer to whether we can survive a freeze is not a simple yes or no. It depends heavily on our species. My kind, the common star jasmine (Trachelospermum jasminoides), possesses a moderate level of cold hardiness. We can typically withstand temperatures down to about 10°F (-12°C) for short periods once we are well-established. However, other members of the jasmine family, like the delicate Jasminum polyanthum, are far more tender and can suffer damage even when the thermometer dips just below freezing, around 32°F (0°C). A young jasmine, still putting down roots, is always more vulnerable than a mature one whose woody stems have weathered a few seasons. Our inherent genetic programming sets the baseline for our survival chances.
When a freeze occurs, the true danger is not the ice crystals themselves, but what they do to the water inside our cells. As temperatures plummet, the water in the spaces between our cells begins to freeze first. This draws liquid water out of our cells through osmosis, leading to dehydration. Simultaneously, the expanding ice crystals can physically puncture and shred our delicate cell membranes. This double assault—dehydration and mechanical damage—is what causes our leaves and tender stems to turn black, become mushy, and ultimately die. It is a catastrophic failure of our internal infrastructure.
We are not passive victims of the cold; we have our own survival strategies. As daylight hours shorten and temperatures gradually decrease in autumn, we receive clear environmental signals. We interpret these signals as a command to begin hardening off. This process involves moving water out of our cells into the intercellular spaces (where freezing is less damaging) and increasing the concentration of sugars and other solutes in our cell sap, which acts like a natural antifreeze. We also slow our growth to a crawl, conserving energy. A sudden, hard freeze before we have completed this hardening process is far more lethal than a gradual descent into colder weather.
While our internal defenses are crucial, emergency help from your gardener can mean the difference between life and death during an unexpected freeze. The most effective action is physical insulation. A thick layer of dry mulch (like straw or shredded leaves) piled around our base protects the most critical part of us: the crown and root system. As long as our roots survive, we can often regenerate new growth in the spring, even if our upper parts are damaged. Throwing a frost cloth, blanket, or even burlap over our canopy traps the geothermal heat radiating from the soil, creating a microclimate that can be several degrees warmer than the outside air. It is vital this covering extends to the ground and is removed during the day. For potted jasmines, our roots are exponentially more exposed; moving us to a garage or sheltered porch is the safest course of action.
The morning after a freeze is a tense time. It is important that your gardener does not rush to prune our blackened, damaged parts. This dead tissue, unsightly as it may be, actually serves as a temporary protective layer against further cold snaps. Premature pruning can stimulate tender new growth that is highly susceptible to the next freeze. The true extent of the damage often takes weeks to become apparent. The gardener should wait until the danger of frost has fully passed and new growth begins to emerge from our stems and base. Only then should they carefully prune back the dead wood to the point of healthy, green tissue. With patience and proper care, we can often make a remarkable recovery.
