Bright indirect light falls, usually, between 1,000 and 5,000 lux, which is the general suitability rating for most houseplants. The light of this intensity is always experienced under a shady tree or near a north-facing window.
Light. Household light varies in intensity, depending on the season and the exposure. South-facing windows provide the most light: direct sunlight within 2 to 3 feet of the window; bright, indirect sunlight up to 5 feet from the window; and semi-shade up to 8 feet away from the window.
250 to 1,000 foot-candles: Low to medium light. 1,000 to 2,000 foot-candles: Bright, indirect light. 2,000-5,000 foot-candles: Direct light.
Indirect or dif- fuse UV light is radiation that has been scattered by the clouds and other elements in the atmosphere, and/or bounced back from UV-reflective surfaces like dry sand or concrete. In fact, a large percentage of the UV light we receive while sitting under a tree or an umbrella is indirect.
West Facing Window - Medium bright and indirect light. This window will have direct sunlight in the morning or evening only. The evening sun is usually stronger and hotter in western windows. This window is suitable for most houseplants.
⛅️ Bright, indirect light: Bright, ambient sunlight, but no direct beams. Usually received by a slightly obstructed south/west/east facing window, or 5'+ away from a window that gets direct sunlight.
East-facing windows provide bright, indirect sunlight during the day and throughout the majority of the year. For plant lovers needing indirect sunlight, an east-facing window is your best bet. West-facing windows also provide indirect sunlight in the early morning and afternoon.
Direct sunlight reaches the Earth's surface when there is no cloud cover between the sun and the Earth, while cloud cover causes indirect sunlight to reach the surface.
Indirect UV is UV that bounces off reflective surfaces like water, sand and snow. For example, when you are sitting near water and your face becomes sunburnt, despite wearing a hat.
Part shade is also defined as four to six hours of direct sun per day, but most of that should come in the morning hours when the sun's rays are less intense. We say that plants which prefer part shade enjoy “cool sun”, meaning direct sun in the morning or evening and protection from the hot midday sun.
Plants that need bright, indirect light do well in east-facing windows. West Facing Window (afternoon sun, hot and bright) - Western windows will receive more indirect light in the early morning and early afternoon.
One foot-candle equals one lumen of light density per square foot, while one lux equals 1 lumen per square meter. To better understand lighting levels and what these figures mean, think of some typical natural lighting situations.
Foot-candles and lux measure the same thing—the amount of visible light that falls on a surface. The difference is that the foot-candle uses the Imperial standard measuring system (feet, pounds, etc.), while the lux uses the metric system (meters, grams, etc.).
Types of Indirect Lighting for Plants
Bright indirect light (over 500 ftc) is typically found near a south, east, or west facing window. Houseplants should be shielded from direct sunlight by a sheer curtain or the dappled shade from outdoors.
Bright, Indirect Light: Pothos plants do best in bright, indirect light. Place your Pothos near a window with a sheer curtain, or in a spot that receives bright but filtered light. Avoid placing the plant in direct sunlight, as this can burn the leaves and cause them to wilt.
Light Levels
Medium - Minimum of 75- to 100-foot candles, preferred level of 200- to 500-foot candles. High - Minimum of 200-foot candles, preferred level of 500- to 1,000-foot candles.
Consider Your Lighting Choices
In one study out of Stony Brook University, fluorescent bulbs in particular were proven to have a higher incidence rate of defects that lead to UV radiation emission levels that could burn skin and evoke cell death, leading to premature skin aging and wrinkles.
You need to have some skin exposed, for example, your forearms, hands and lower legs. But you can still make vitamin D even if you sit in the shade. Sitting inside by a sunny window doesn't count because glass filters out the UVB rays – the type of light that is needed to make vitamin D.
Windows in the passenger cabin are generally constructed of three layers of plastic. These materials are highly effective at blocking both UVA and UVB, ensuring passengers are not at risk.
Bright Indirect Light Examples
Here are some examples of bright indirect light: Near a North-Facing Window: North-facing windows receive less direct sunlight, providing more diffused light.
Indirect sunlight is when your plant is in a shady area within an area that receives bright sunlight. It may be behind another plant or a piece of furniture. Partial sunlight is when the light is direct only during certain times of the day, such as in the morning or late afternoon.
If you have larger windows, you can place plants farther away and they will still receive plenty of light, while the smaller windows will only provide a limited range of sunlight. If you can, it's best to place plants directly in the window, especially if there are obstructions or no more than 2-3 feet away.
Indirect lighting is unsuitable for activities that require concentration and high vision. Due to the soft effect of indirect light, it can cause eye fatigue. Therefore, we do not recommend indirect lighting in offices unless there is another bright light source, such as a UGR <19 luminaire.
Morning sun is tends to be superior to afternoon sun because it will dry dew from leaves of the plant, which reduces disease, and it is cooler. Most plants, even those that tolerate full sun, will appreciate even momentary respite from the afternoon sun.
Full sunlight with zenith sun produces an illuminance of about 10 000 foot-candles on a horizontal surface. Full moonlight provides an illuminance of about 0.02 foot-candles. Adequate illumination for reading is taken to be about 10 foot-candles; that for machine shop work is about 40 foot-candles.