Moving your indoor plants outside for the summer, often called “summering,” can provide a significant boost to their health and growth. The natural elements of increased light, better air circulation, and rain offer benefits difficult to replicate indoors. However, a sudden transition to the fluctuating outdoor environment can cause severe shock or damage. Successfully moving houseplants requires careful timing and a gradual acclimatization process to ensure a smooth transition.
Determining the Safe Timing
The most important factor in determining the move-out date is the ambient temperature, specifically the minimum nighttime temperature. Most common tropical houseplants, which make up the majority of indoor foliage, require consistently warm conditions to thrive. Waiting until all danger of frost has definitively passed is the absolute first step.
A general guideline is to wait until nighttime temperatures remain reliably above 50–55°F (10–13°C). Temperatures below this range can cause chilling injury to tropical species, leading to stunted growth or leaf damage. Some highly sensitive tropical varieties, like certain orchids or tender foliage plants, may prefer a slightly higher minimum of 60°F (15°C) before being left outdoors overnight. Checking the average last frost date for your specific region provides a good starting point, but monitoring the current weather forecast for consistent warmth is more reliable than relying on historical averages alone.
The Process of Hardening Off
The transition from indoor to outdoor life requires a methodical acclimatization process known as “hardening off.” This procedure gradually introduces the plant to the increased intensity of natural light, wind, and temperature fluctuations. Skipping this step often results in leaf scorch, a form of sunburn where foliage tissue is damaged by sudden intense ultraviolet light.
The hardening off process should span a minimum of 7 to 14 days, allowing the plant’s waxy cuticle layer to thicken in response to stronger light and wind. Begin by placing the plant in a fully shaded, sheltered spot, such as under a covered porch, for just one to two hours on the first day.
Each subsequent day, increase the duration of outdoor exposure by one to two hours, while slightly increasing the light intensity. After two to three days in full shade, shift the plant to an area that receives a brief period of gentle morning sunlight. Morning sun is significantly less intense than the harsh midday or afternoon rays, which can quickly burn unacclimated leaves.
By the end of the first week, the plant should be spending nearly the entire day outdoors, protected from the most intense afternoon sun. Over the last few days, begin introducing it to its final, brighter light conditions. This slow, incremental exposure builds the plant’s tolerance and prevents growth shock that can halt development for weeks.
Selecting the Optimal Outdoor Location
Once hardening off is complete, place the plant in a permanent outdoor location that matches its indoor light requirements, while accounting for the difference in intensity. Even a bright indoor window provides only a fraction of the light energy found in a shady spot outside. Plants that thrived in bright indirect light indoors will generally do best in a fully shaded or dappled-shade location outdoors.
Avoid placing any houseplant, even sun-loving varieties like cacti, directly into unfiltered midday or afternoon sun. The quality of outdoor sunlight is too harsh and will likely lead to irreversible leaf burn. Additionally, the chosen location must offer protection from sustained high winds, which can rapidly desiccate foliage and physically damage fragile stems.
Drainage is a technical consideration. Potted plants are susceptible to heavy rainfall, so the container must drain completely to prevent waterlogging. If the pot sits in a saucer, empty it immediately after rain to prevent roots from sitting in standing water, which promotes root rot.
Post-Transition Care and Monitoring
After the transition, plants require adjustments to their care routine due to the dynamic outdoor environment. Increased light, higher temperatures, and improved air circulation lead to a higher rate of transpiration, meaning the soil will dry out much faster. You will likely need to increase the frequency of watering, potentially checking the soil daily during hot or windy weather.
The enhanced conditions also stimulate more vigorous growth, which increases the plant’s nutritional demands. If you typically fertilize, transition to a more frequent feeding schedule, often once every two to four weeks. Use a balanced, diluted liquid fertilizer to support this growth spurt.
Continuous monitoring for outdoor pests is necessary throughout the summer. Plants outdoors are exposed to a wider array of insects, including slugs, snails, aphids, and scale. Regularly inspecting the undersides of leaves and the soil surface allows for early detection. Treat any infestations with horticultural soap or neem oil before they become established and are carried back inside in the fall.