Plant light requirements: What does full sun, part sun, and shade mean?

You’ve seen it on plant tags and signs: full sun, part sun, part shade, and shade. And often, you’ll see more than one listed for the same plant. So what do these light requirements actually mean? Let’s break it down so you’ll never have to guess if a plant will work in your garden again. 

First, a bit of background: Plants have different light needs based on their natural growing habits. Going back to biology class, you may remember that all plants need light in order to grow. That’s because they use light as energy through photosynthesis. Some plants need more energy than others to thrive. Typically, plants with lots of flowers or fruits need as much sun as they can get because putting on blooms or fruit requires a lot of energy. That’s also why you may notice most plants that do well in shade tend to have more interesting foliage and less significant blooms.    

“Full Sun” Light Requirements

A plant with full sun light requirement needs 6 or more hours of direct sun a day. These plants are sun lovers. They usually can’t get enough sun and will not produce blooms or new growth if they are in the shade. 

Southern & Western Exposure: 

The area of your garden that will likely get the most sun is your southern-facing side. Southern exposure gets the most intense, direct light. Western exposed areas can also work for full sun plants because the western-facing area of your garden will get the most intense, afternoon sun. 

Special Care: 

You will need to keep an eye on your full sun plants for water and fertilizer needs. Because they are basking in the heat, they tend to dry up and lack nutrients far faster than shade plants. In the summer heat, make sure you are checking your outdoor plants daily and indoor plants weekly for additional water or fertilizer needs. 

Signs your plant may not have enough sun: 

• Failure to Bloom: If the plant is a flowering variety, it might produce fewer flowers or none at all due to inadequate light.
• Leggy Growth: The plant may become tall and spindly with long internodes (the spaces between leaves), as it stretches towards the light source.
• Leaning Towards Light: The plant may lean or grow towards the nearest light source, indicating it’s trying to get more light.
• Slow Growth: The plant's overall growth rate may slow down significantly due to insufficient light for photosynthesis.
• Pale or Yellowing Leaves: Lack of light can cause leaves to lose their vibrant green color, turning pale green or yellow.
• Small Leaves: New leaves may grow smaller than usual and can be fewer in number.

If you notice any of these signs, consider moving your plant to a different spot with more sun. Or trying again with a plant that has lower sunlight requirements. 

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“Part Sun” Light (and “Part Shade”) Requirements

A plant with part sun light requirements needs 3-6 hours of direct sun. These plants typically prefer direct, morning light and like some but not all the sun through the day. Think of these as the goldilocks of the plant world. 

Eastern (And Sometimes Western) Sun Exposure: 

The area of your garden that will work best for part-shade plants is the Eastern side. That’s because this side will get morning sun, which is less intense than afternoon sun. As mentioned above, if you have bright Western exposure, that may be too intense for part-sun plants, but it depends on the plant’s heat and direct sun tolerance. 

Special Care: 

You’ll want to keep an eye out for signs that your plants are getting too much direct sun. Depending on the plant, it may look like wilting or browning and dropping leaves. 

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“Shade” Light Requirements

A plant with a shade light requirement needs less than 3 hours of sun per day. 

Northern Sun Exposure: 

Plants with shade light requirements will do best on the Northern area of your house. The absolute shadiest spot in terms of sun exposure will be the Northeast corner – which will only get a bit of indirect, morning sun. 

Signs your plant may be getting too much sun: 

• Leaf Scorching: This is one of the most common signs. The leaves may develop brown, crispy edges or spots, particularly on the side of the plant facing the sun.

• Wilting: While wilting can also be a sign of under-watering, in the context of excessive sunlight, it indicates that the plant is losing water faster than it can absorb, even if the soil is moist.
• Leaf Color Changes: The leaves might turn yellow or develop a bleached appearance, indicating they are stressed by too much light.
• Faded Colors: The vibrant green color of the leaves may fade, making them appear washed out.
• Dropping Leaves: Excess sunlight can cause shade plants to shed leaves prematurely.
• Slow Growth: Overexposure to sunlight can stress the plant, slowing down its growth or even causing it to stop growing altogether.

If you observe any of these signs, consider moving your plant to a location with less direct sunlight or providing additional shade – with more plants! 

It’s important to understand the light needs of your plants to give them the best chance for success in your garden. Keep in mind, you’ll also want to look at structures like fences, walls, trees, and anything else you have around your garden that may affect the amount of sun that reaches your plants. 

Although sunlight isn’t the only variable to a thriving garden, it is certainly one of the most important. Good luck in the garden!

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