Indoor Plants: Know Your Indoor Light Levels
Authored by Leah Chester-Davis
Authored by Leah Chester-Davis
Houseplants bring a bit of nature inside and can lend lovely visual elements to your indoor space. To keep them looking their best, consider the plant’s light requirements. Just like outdoor plants have specific requirements such as shade or sun, indoor plants need different levels of light. They typically fall within low-light, medium-light, or high-light requirements, which refers to the light intensity levels.
Why is light so important? It’s how plants produce food and get their energy to grow and thrive. Without it, they often turn a yellowish or pale color because they can’t produce chlorophyll, which is what makes them look green and healthy. They may become leggy, drop their leaves, and die.
Light levels in the home typically depend on windows or artificial lights. Houseplants can thrive with either, though it’s important to select plants that match the light environment in your home.
Depending on the plant, windows might supply adequate light, but other factors affect both light levels and intensity, such as the proximity of the plant to the window, the direction the window faces, and the window size. Window coverings like curtains or shades, outside overhangs or porches, trees, or even shade from other buildings can affect light levels. The amount of light also changes with the season, so moving houseplants from one window to another, depending on the time of year, may be helpful. Even the color of your walls can affect light intensity. Bright, light-colored walls are more reflective and can increase light intensity. Dark walls and surfaces can decrease it.
When adding indoor plants, consider light levels in various areas of your home and select plants accordingly.
Light duration can make a difference. The longer the period of light doesn’t always equate to what is best for the plant. Some plants are sensitive to day lengths; others are not.
Some plants are considered short-day plants, meaning they need 11 or fewer hours of light during a 24-hour period. In other words, some plants are just like some people. Some need a longer period of darkness to get the best rest so they can end up looking their best. Thanksgiving and Christmas cactus, kalanchoes, and poinsettias are considered short-day plants. Too much light for a period longer than 11 hours may affect reduce blooming. Put them in a spot with the right amount of light and they show off.
On the other hand, some plants are considered long-day plants. To flower, they need light that exceeds the hours of the night period, more than 12 hours each day. Among long-day plants are African violets, gloxinia, and tuberous begonias.
When a plant is called day-neutral, it is insensitive to day-length differences and its flowering cycle will not be affected. Gerbera daisies are an example.
Plants need both red and blue light for photosynthesis. A lot of indoor lighting is from incandescent lights, which provide primarily red light. They also put off a lot of heat, so plants do not need to be placed too close to them.
Fluorescent lighting or special grow lights may supply both red and blue light, which are important energy sources for plants. They are energy efficient and produce little heat. They also are available in many different sizes.
Light-emitting diodes or LEDs are also energy-efficient and can be a good choice for small houseplants.
See our guide on How to Choose Grow Lights for Indoor Plants and Seedlings. When selecting lights, check the manufacturer information for details.