How to Determine Sunlight Levels for Houseplants

Tips on Bright, Indirect, Low Light, and Other Factors

Potted aloe vera plant on windowsill

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Too much or too little light can quickly stress a plant, which makes them more prone to disease, pests, and premature death. Fortunately, most plants come labeled with information about their sunlight preferences. However, finding optimal lighting for your plant can take some trial and error, so you'll have to monitor it closely.

It's often easier to determine the amount of sun in your yard as opposed to inside. Outdoors you can clearly see where it's shady and where the sun is hitting directly. Light is more subtle indoors. To figure out if a houseplant will be happy in your space, it's helpful to know the different types of light you have in your home.

Determining Indoor Plant Lighting

There are three main types of interior plant lighting:

  1. Bright Light: Bright light means a sunny southern or western facing window that receives direct light all day long. It should get a minimum of five to six hours of sunlight each day, preferably more. This can be hard to accomplish during the winter but resist the temptation to move your plant closer to the window. Most plants that need bright light will not be able to handle the cold draft that increases the closer you move toward a window.
  2. Indirect Light: Indirect light can be found in places with an east-facing window, or in an interior of a room that receives full light from a south- or west-facing window.
  3. Low Light: Many rooms qualify as low light, especially in winter. Rooms with north-facing or partially shaded windows would qualify as low light situations. If you can't easily read a newspaper, it's probably low light.

Other Indoor Plant Needs

When you're determining how much light your houseplant will require, you'll also need to consider the rest of the environment. Finding the right lighting level for houseplants is not an exact science, but keep these factors in mind when choosing a spot to place your plant.

  • Temperature: Plants positioned near a source of heat, such as a heating vent, may not be able to handle as much bright light as a similar plant in a cooler spot. If your plant often looks like it's wilting, even though you give it regular water, the heat source may be part of the issue.
  • Humidity: As with temperature, a low level or lack of moisture in the air can cause plants to wilt and stress. If that happens, you can usually leave the plant in its optimum light conditions if you also mist the plant regularly or provide a nearby humidifier.
  • Duration of Sunlight: Most plants need a full day's worth of sunlight. Luckily many plants go dormant during the winter—including most houseplants. However, you may still need to provide some supplemental lamp lighting, especially if you can't offer a spot with ideal light conditions for your plant.
  • Seasonal Changes: It's not just day length that varies as the seasons change. The angle of the sun is also different. When the days are long and the sun is high in the sky, your western facing window may get full sun for the entire day. When the days shorten, and the low sun only comes in at an angle, even a western facing window will not be enough light for a plant that craves full sun.

Remember, if your plant seems happy and healthy, let it be. If not, try another spot.