The String of Pearls plant (Senecio rowleyanus) is a popular trailing succulent prized for its unique, pea-shaped foliage. While commonly grown as an indoor houseplant, its native environment in arid southwestern Africa suggests potential for outdoor growth. Moving this plant outside is possible and can promote vigorous growth, but success depends entirely on specific climate conditions and modified care routines. Survival requires careful attention to temperature, light exposure, watering frequency, and seasonal adjustments.
Determining Climate Suitability
The decision to place a String of Pearls plant outdoors hinges on local temperature and climate, as this succulent is highly sensitive to cold. Senecio rowleyanus is not frost-tolerant and cannot survive freezing temperatures. The minimum temperature it can withstand is around 40°F (4°C).
For year-round outdoor cultivation, the plant is best suited to USDA Hardiness Zones 9 through 12. These zones experience mild winters where the temperature rarely drops below the plant’s survival threshold. In these frost-free areas, the String of Pearls can be grown in containers or as a ground cover.
In all other regions, outdoor placement must be temporary, lasting only through the warm months. Move the plant outside only after all danger of frost has passed, and nighttime temperatures are consistently above 50°F (10°C). Ignoring this requirement results in rapid decline, typically manifesting as mushy, discolored foliage due to cold damage.
Outdoor Care Requirements
Once climate conditions are met, the outdoor environment demands specific adjustments to the plant’s care regimen, especially concerning light. Outdoors, the String of Pearls requires bright, indirect sunlight for optimal health, often needing six to eight hours of light daily. Placing the plant in a location that receives the gentler morning sun is ideal, as this intensity is less likely to damage the foliage.
The spherical leaves, which store water, are susceptible to sun-scald from harsh, direct afternoon sun. This intense exposure can cause the pearls to blister, scorch, and turn brown, indicating irreversible damage. Positioning the plant under a covered patio, a porch, or in the dappled shade of a tree provides necessary protection from powerful midday rays.
Outdoor watering must follow the succulent principle of allowing the soil to dry out completely between waterings. Hanging baskets outdoors, particularly those with good airflow, will dry significantly faster than indoor pots. This requires more frequent observation, though the plant remains susceptible to root rot if overwatered.
Soil and Pests
Well-draining soil remains paramount when the plant is outside, as outdoor containers are exposed to rain. A specialized cactus or succulent potting mix, amended with materials like perlite or pumice, ensures rapid drainage. Containers must have functional drainage holes to prevent water from pooling, which is the primary cause of root rot. Increased exposure also means greater risk from common garden pests like aphids, mealybugs, and slugs, necessitating regular inspections.
Seasonal Acclimation and Winter Preparation
Plants that spent the winter indoors must undergo a gradual process of acclimation, known as hardening off, before being left outside full-time. This slow introduction prevents shock from sudden changes in light intensity, temperature, and wind exposure. The process should take seven to ten days, beginning with placing the plant in a fully shaded, sheltered location for just a few hours.
Each day, the exposure is increased by an hour or two, and the plant is moved into slightly brighter light, such as morning sun. This methodical transition allows the plant’s tissues to adjust to stronger ultraviolet radiation and fluctuating outdoor temperatures, preventing leaf burn and stress. Watering should be consistent during this period, avoiding fertilization until the plant is settled in its outdoor spot.
Bringing the Plant Indoors
The reverse transition is required when temperatures begin to drop in the autumn, usually when nighttime lows consistently fall below 50°F (10°C). Before moving the String of Pearls back inside, a thorough pest inspection is crucial to prevent introducing garden pests to the indoor environment. This involves closely examining the soil surface, the underside of the leaves, and the stems for any signs of insects.
Cleaning the plant with a gentle spray of water or an insecticidal soap solution helps eliminate any lingering pests or eggs. Once cleaned, the plant should be placed in a separate area, away from other houseplants, for a one-to-two-week quarantine period. This isolation allows for the observation of any newly hatched or missed pests before the plant is safely integrated with the rest of the indoor collection.