The spider plant, Chlorophytum comosum, is a popular and resilient houseplant known for its variegated foliage and ease of care. Originating in tropical and subtropical southern Africa, its ability to survive winter outdoors depends entirely on the local climate and the severity of cold temperatures. Keeping this perennial outside presents a substantial challenge for most gardeners due to its sensitivity to cold.
Defining the Spider Plant’s Cold Tolerance
Plant hardiness classification provides the answer to whether the spider plant can remain outside year-round. This species is suitable for perennial growth in USDA Plant Hardiness Zones 9 through 11, which represent the warmest regions. These zones typically experience average minimum winter temperatures that remain above 20°F to 30°F.
Foliage begins to show signs of stress and damage when temperatures drop below 50°F (10°C). This chill results in slowed growth and leaf discoloration, particularly browning at the tips. The critical threshold occurs around 35°F (-1.7°C), where sustained cold will likely cause significant structural damage.
Spider plants are not tolerant of frost; even brief exposure to freezing temperatures can be lethal. In zones colder than 9, such as Zone 8 or lower, the plant will not survive an entire winter outdoors without substantial protection. Its tropical origins and high water content make the plant highly susceptible to cellular destruction caused by ice formation.
The Effects of Freezing Temperatures on Plant Tissue
When the temperature drops below freezing, water within the plant’s tissues turns to ice, initiating a destructive cellular process. Ice crystals typically form first in the extracellular spaces, drawing water out of the cells. This initial freezing causes the protoplast to shrink and leads to dehydration.
If the temperature continues to fall or cold exposure is prolonged, ice can form directly inside the cells, which is usually fatal. The physical expansion of ice within the cell walls causes them to rupture and destroys the cellular membranes. The visible result of this freeze damage is often mushy, blackened, or limp foliage.
Damaged leaves will not recover, signaling that the plant has sustained cold injury. While the above-ground foliage may be completely destroyed, the plant’s robust, tuberous root system may sometimes survive a short freeze if insulated by the soil. The plant may die back completely but still sprout new growth in the spring.
Practical Strategies for Outdoor Winter Survival
For gardeners in borderline areas, such as the warmer parts of Zone 8 or Zone 9, several measures can be taken to mitigate the risk of cold damage. Utilizing microclimates is an effective strategy, which involves placing the plant in a location that naturally retains more heat. A spot against a south-facing, sunny wall or under a dense evergreen canopy can provide beneficial warmth.
If the spider plant is growing in the ground, applying a thick layer of organic mulch, such as straw or wood chips, is recommended. This insulation helps regulate the soil temperature and protect the sensitive tuberous roots from deep freezes. Even if frost kills the exposed foliage, the protected roots may allow the plant to regrow when warmer weather returns.
The most reliable strategy for outdoor winter survival involves growing the spider plant in a container. This allows the gardener to easily move the plant into a garage, covered porch, or indoors when temperatures dip below 50°F (10°C). For regions experiencing consistent and deep freezing (Zone 7 and colder), bringing the plant indoors remains the only viable method for overwintering.