Moving indoor plants outside for the warmer months is a common practice that can significantly accelerate their growth and improve overall health. Houseplants, many of which originate from tropical environments, benefit immensely from the naturally higher light intensity and increased humidity found outdoors. Fresh air and natural rainfall help clean dust from the foliage, allowing for more efficient photosynthesis. However, the transition from a stable indoor setting to the fluctuating outdoor conditions must be done with great care to avoid stressing the plant.
Determining the Right Time for the Move
The timing for moving tropical houseplants outdoors is dictated entirely by temperature, specifically the minimum temperature at night. Most common foliage plants should not be moved outside until the risk of late spring frost has completely passed. A general guideline is to wait until nighttime temperatures are reliably staying above 50°F to 55°F. Exposure to temperatures below 50°F can stunt a plant’s growth for several weeks.
Nighttime lows are a stronger factor than daytime highs because a sudden drop can shock the plant’s system. Temperatures below 35°F can kill the leaves of most houseplants. Keeping a close watch on the local forecast is important, and if an unexpected cold snap is predicted, plants should be temporarily moved into a garage or covered area.
The Gradual Process of Acclimation
The process of adjusting a plant to the harsher outdoor elements is often called hardening off, and it is a necessary step to prevent immediate damage. Indoor plants are accustomed to filtered light and still air, meaning sudden exposure to direct sunlight, wind, and heavy rain can scorch the leaves. This sun damage can occur in just a few hours and may result in permanent white or brown patches on the foliage. The goal is to slowly build the plant’s resilience over a period of about seven to fourteen days.
Begin by placing the plant in a deeply shaded, sheltered location, such as on a covered porch, for just one to two hours a day. Gradually increase the duration the plant spends outside, checking frequently for signs of stress like wilting or discoloration. After about a week, slowly introduce the plant to stronger light, perhaps moving it to a spot that receives bright, dappled shade or gentle morning sun. The increased light, heat, and wind will cause the soil to dry out much faster, so a revised watering schedule is necessary.
Necessary Steps Before Bringing Plants Indoors
The summer vacation must end before the weather turns too cold, generally when minimum nighttime temperatures begin to drop consistently below 60°F, which often occurs around mid-September. Preparing for the return indoors is primarily a matter of pest management, as outdoor conditions allow natural predators to control insect populations that would otherwise thrive inside. A thorough inspection is needed before the move, checking the undersides of leaves, leaf joints, stems, and the top layer of soil for any signs of unwanted hitchhikers.
Common outdoor pests like spider mites, aphids, and scale insects can quickly infest an entire indoor collection if they are not eliminated. To prevent an outbreak, give each plant a shower with a strong stream of water from a hose to physically dislodge any insects. After rinsing, a preventative treatment with an insecticidal soap or horticultural oil can be applied, ensuring the product is labeled for use on houseplants. For hard-bodied pests like scale or mealybugs, wiping them directly with a cotton swab dipped in rubbing alcohol can be an effective, targeted spot treatment. Finally, isolating the returning plants in a separate room for two weeks is a practical measure to catch any pests that were missed.