Yellow leaves high light orchid
Updated: March 16, 2021

Symptoms of excess sunlight on indoor plants

  • Some plants grow best in partial sun or shade. When shade-loving plants are exposed to full sun, leaf scorch or sunburn can occur. 

  • Strong sun and heat cause the breakdown of chlorophyll in the leaf. Damage appears as pale, bleached or faded areas. These areas eventually become brown and brittle.

  • Symptoms are more severe when strong sun is combined with dry soil conditions.

  • Indoor Plants can be classified according to their light requirements: low, medium, or high.

  • Important aspects of indoor light are intensity, duration, and quality. Light intensity depends on the distance of the light source from the plant.

  • The brightest light is found in a south facing window, bay window or sun room. The duration is the length of time the plant receives light.

  • Most flowering indoor plants are indifferent to duration. However, some indoor plants such as poinsettia, kalanchoe and Christmas cactus only flower when day length is short, 11 hours or less. Plants need some period of darkness to develop properly; so do not expose them to more than 16 hours of light.

  • Artificial lighting can improve the quality of light the plant receives. Red, far-red and blue wavelengths are most important for plant development. Incandescent plus fluorescent light sources or horticultural grow lights best mimic natural sunlight.

Moving indoor plants outside

  • Sunburn may also occur on indoor plants that are adapted to low light conditions and moved directly outdoors without a "hardening off" period. To avoid sun scorch on indoor plants, place plants in full sun for 2 hours per day initially and gradually increase the length of sun exposure.