Bright Indirect Light: This is direct sunlight that is filtered or diffused either through a translucent blind or a sheer curtain. Think of this light as being outside on a cloudy day... there is still light, but it's not harsh. Basically, every plant will thrive in this light.
In general, the sunlight coming through a glass window is good for plants. A couple of things to watch for - if the plant leaves are resting against the glass, the sunlight may be hot enough there to burn the plant leaves. This doesn't actually hurt the plant, just makes a brown spot in the leaf that it hits.
Direct sunlight and high temperatures should be avoided as much as possible. This may sound contradictory, because light and heat are essential for the growth of plants, so-called photosynthesis. For an optimal growth there should be a good balance in climate between temperature, light and humidity.
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. East and west-facing windows provide some direct light up to 3 feet and indirect light up to 5 feet away.
Does light through a window count as direct or indirect? The light that passes through a window is considered indirect, as the rays will be diffused and won't have the same intensity. However, it depends on the window. If your window is south facing and there are no obstructions, it can be considered direct light.
Better Health
When we have access to natural light throughout the day—even sun through a window—we're also more likely to be healthier. According to research from Cornell University, people living and working in an environment that provides window sunlight have fewer headaches and blurred vision issues.
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.
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.
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. In gardening, sunlight falling directly on the plant is direct sunlight, while indirect sunlight refers to shaded areas.
Many full sun plants thrive under sunny skies from dawn to dusk, but others may need a bit of a break. If a plant is labeled heat or drought tolerant and full sun, it is a good bet it will tolerate even the most intense summer sun day in and day out.
Any amount of sun greater than six hours is considered full sun. What is Part Sun? Part sun is defined as four to six hours of direct sun per day. Not all those hours need to be accrued consecutively—it could mean a few hours of morning sun plus a few more in the afternoon.
Leaves are supposed to be a rich green color, but if there is not enough light, they will turn pale green, yellow, and then eventually drop off. For plants with variegated leaves, instead of being colorful, they will revert to an all green color in order to absorb enough sunlight as possible.
Direct sunlight refers to sunlight in which the path of light from the sun to the plant is a straight line. For example, most windowsills provide direct sunlight. You can also create direct light with LED grow lights if your home doesn't get enough direct sunlight to support your plant collection.
Since clouds block sunlight, they do affect the process in both plants growing on the land and aquatic plants. Photosynthesis is also limited when daylight hours are fewer in winter. The photosynthesis of aquatic plants can also be limited by substances in the water.
East and west-facing windows provide something in between. For plants that need lots of light, south-facing is ideal. In the case of shade-loving plants, it is good to place the plant farther away from the window or move it to a place where other objects will hit the light first and have a filtering effect.
Indirect light is sunlight that either passes through a medium—a window shade or the leaves of a tree—or reflects off another surface before reaching a plant. Most indoor settings only provide indirect light.
Most plants need some light in order to grow, but shade-loving plants can easily get by with indirect light, or even artificial light from regular light bulbs.
The Summer season is caused by direct sunlight striking the Earth. It is because of the Earth's axial tilt which is about 23.5 degrees. Due to this tilt, the Sun's angle changes throughout the year which causes the seasons to occur.
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.
Medium-Bright Light
West-facing windows are your best choice here as the afternoon sun is more intense. You could also use a South-facing window so long as you keep the plant several feet back.
The short answer is no. Grow lights are not direct sunlight, but they serve as a suitable alternative for plants when natural sunlight is scarce. While they provide the necessary light spectrum and intensity for photosynthesis, grow lights cannot replicate the full range of benefits that natural sunlight offers.
Southern facing windows will provide the most light (especially during winter). You can place all of your houseplants that love sunlight in windows facing this direction. Just remember that with a lot of sun comes higher temperatures. Be mindful of your plants and if their foliage starts to burn.
The best time to water indoor plants is during the morning hours, before the sunshine is in full force. Watering in the morning is also helpful for plants that do not get as much light as you'd like, because they're not sitting in wet soil for too long.
Sun loving coleus and bronze leafed wax begonias may work. Just keep the soil moist. Purple Heart (Setcreasea purpurea), pentas, and four o'clocks are other annuals to consider. For perennials try dwarf Mexican petunia (Ruellia), lilyturf, daylilies, and speedwell (Veronica).