Indirect vs Direct Sunlight: What's the Difference? - Backyard Boss
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Indirect vs Direct Sunlight: What’s the Difference?

Sunlight is a constant in our daily lives, but when it comes to gardening and plant development, we have some degree of control over its intensity. This control categorizes sunlight into direct, indirect, and high, low, and medium lighting levels for indoor and outdoor plants.

Continue reading to learn more about the distinctions between direct and indirect sunlight, as well as the various levels of intensity. This will also help you measure light for your plants.

The Sunlight’s Role In Plant Development

Houseplant leaves facing a window with sun streaming in
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Sunlight is an energy source that plays a significant role in plant growth. Without it (or even artificial light), most plants would struggle to grow because they rely on sunlight for photosynthesis. When the sun emits light, it provides energy for photosynthesis.

During photosynthesis, carbon dioxide, water, and light energy are converted into glucose (a type of sugar) and oxygen that plants need for healthy growth. This is the same oxygen that humans breathe in and live!

Types of Lighting

Plants need some degree of sunlight to sustain themselves. However, it’s essential to understand sunlight intensity. Knowing how much sunlight your garden receives will help you grow plants that would best suit those lighting conditions. When keeping track of how much sunlight your garden receives, pay attention to the following:

  • Do you receive more sunlight in the morning or the afternoon?
  • Are you growing fruit and vegetable plants or herbaceous plants?
  • Do you live in the northern or southern hemisphere?
  • What plants (overhanging trees or vines) or structures (a window screen, a gazebo, or a tool shed) do you have in your garden that could block light from reaching your plants outside and inside your house?

What Is Direct Sunlight?

ground cover
Image Credit: Lakeisha Ethans for Backyard Boss

Direct light refers to the placement of indoor and outdoor plants in a way that they receive full sun exposure. For example, houseplants placed in west or south-facing windows or balconies will receive direct sunlight compared to those in the north.

Outdoor plants requiring full sun need at least six hours of sunlight daily. Imagine the vegetation of open fields and pastures. The plants that grow there get full sun exposure.

Cacti and succulents are notorious for thriving under the sun. If they are placed in a location with insufficient light, they are known to grow crookedly in search of more sunlight. Most fruit and vegetable-producing plants require some amount of direct sunlight to produce a yield.

If you live in the northern hemisphere, south-facing windows receive the brightest and most intense light into the home, while west-facing windows permit bright light that peaks in the afternoons but is cool and indirect for the rest of the day.

What Is Indirect Sunlight?

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Indirect sunlight refers to sunlight that has been filtered, reflected, or diffused by an object or surface before it reaches your plants. Indirect sunlight is often softer and less intense than direct sunlight and may produce less heat and brightness.

Plants that require indirect light, like the Snake Plant, Boston Fern, and Golden Pothos, can thrive in partial sun, semi, or full shade. Partial sun refers to a light exposure range of two to four hours, while dense shade provides complete relief from direct sunlight.

Understanding Indirect Sunlight Intensity

Indirect sunlight intensity refers to the amount of sunlight that reaches a surface after it has been filtered, reflected, or diffused by an object or surface. Here’s the difference between various sunlight intensities.

1. Low Light

peace lily
Image Credit: Lakeisha Ethans for Backyard Boss

Low light describes a small degree of sunlight for indoor plants. If no direct sunlight shines into a room and you can still read print with the natural light that filters in your room, then that is considered low light. You can place low light-loving plants, like Peace Lilies, Anthuriums, and Snake Plants, near a north-facing window, as there is ample shade throughout the day. You can also place them by an east-facing window with brighter indirect light and gentle intensity.

2. Light Shade

Flowers on stairs
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Light shade is the first class of shade for outdoor plants. It is usually recommended for sun-loving plants like Azaleas, Rhododendrons, and Macrophylla Hydrangeas, which grow in areas with high temperatures. Regarding sun exposure, plants that prefer light shade receive three to five hours of direct sunlight.

3. Partial Shade

bleeding heart
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If your garden receives two hours of direct sunlight or is shaded for half of the day, then that area is considered partial shade. Other forms of partial shade include the shade under a tree or the reflection of light bouncing off buildings. When it comes to light intensity, the two hours of exposure is usually the gentler morning sun over the hot midday sun. Most partial shade-loving plants, like Bleeding Heart, Japanese Primrose, and Lily of the Valley, blossom at higher rates with little sunlight.

4. Full Shade

Pink, green, and yellow leaves of a coleus plant
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Full shade is characterized by less than an hour of direct sunlight and is demonstrated by stippled sunlight peeking through tree canopies. Buildings, fencing, or climbing structures can cast full shade onto a garden by obstructing the sun’s rays from reaching plants.

Plants that prefer full shade include Coleus, Daffodils, and Yew. Full shade helps retain soil moisture but often affects soil fertility. This is because maintaining adequate levels of nutrients can be challenging due to insufficient heat levels to encourage microorganisms in the soil. Besides that, too much soil moisture can cause root rot.

5. Dense Shade 

close up wild ginger
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Dense shade is the ultimate relief from sunlight, with little to no indirect light reaching the garden. Think of the opaque shade under an evergreen tree or the shade under a deck or a dark corner. The soil under dense shade is usually dry and dark or wet and compacted, both of which are difficult conditions to grow plants. Usually, ground-covering plants, like Wild Ginger, Bishop’s Hat, and Japanese Pachysandra, are best suited to grow in dense shade.

How to Know if Your Plant Is Receiving Enough Light

lots of potted houseplants of different varieties gathered together
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Providing plants with the ideal lighting conditions isn’t simple because of their changing requirements. While it’s essential to consider the light requirement information provided on your plant’s tags or packaging, it’s also worth remembering that some plants can adapt to different lighting conditions.

For instance, some plants that thrive in direct sunlight may become leggy and stretch to reach for more light. Some tags may also provide a range of lighting conditions the plant can tolerate, such as “partial to full shade,” in which case the first option is usually the best.

To ensure your plant gets the right amount of light, it’s best to monitor its growth. Check for foliage coloration, whether the plant uses the water you provide, and the firmness of stems and leaves.

Beaming With Pride!

Direct and indirect light are located on opposite sides of the lighting spectrum. Direct light refers to full sun exposure with medium to high light intensity. Indirect light is divided into partial sun and partial shade, which has medium to low sunlight intensity.

Many plants can grow well under both types of light. However, most plants flourish in a range that falls somewhere between the two extremes of sunlight exposure.

Leave your experiences, thoughts, and questions in the comment section! And share with friends and family who might find this helpful.