You know that plants need a certain amount of light to survive. Light is necessary for photosynthesis, which is how they get most of their nutrition.
Even though light is necessary for plants, they can get too much. Too much sunlight can lead to problems like yellowing and browning leaves, sun scorch and several other things.
In this guide we’ll take a look at the signs your plant is getting too much light, and what you can do about it.
- What is Too Much Light?
- Measuring Intensity and Duration
- 8 Signs of Too Much Light On Your Plant
- Adjusting Light
- Summing It Up
What is Too Much Light?
First, let’s look at what constitutes too much light. How much light a plant needs can vary greatly from plant to plant. However, there are two main components of light that are universal. These are duration and intensity.
If you’ve ever gotten a sunburn, you may be more aware of these two components then you think. You are more likely to get sunburn if you spend a lot of time out in the sun, which is duration. If the light is very strong, known as intensity, this also increases your risk of sunburn.
When combined, you have a high duration and intensity. This poses the greatest risk of sunburn and will cause a more severe burn than either factor on its own.
Light duration is easy to understand. It’s simply how long your plant is exposed to light in a day. However, the duration of light your plant needs isn’t always so simple.
It’s easy to assume that plants need light throughout the daylight hours to be their healthiest. After all, more light allows for more photosynthesis, which helps the plant grow.
However, many plants also require periods of darkness. Christmas cacti and chrysanthemums, for example, will only flower if they get periods of darkness that last for 12 hours or more. These plants are known as short-day plants, because they need a shorter light duration.
Other plants, including lettuce and spinach, need longer days to flower. These are known as long-day plants.
Other plants, like tomatoes, aren’t affected by light duration. They are known as neutral-day plants.
Light intensity is also important. You’ve probably experienced this yourself. When you are in the sun, you’ve probably noticed that there are times the sun feels hotter or stronger than others. You may also notice that the light from the sun seems brighter.
Light intensity can actually affect your plant more than duration. One reason for this is that higher light intensity also raises the temperature. Your plant must use water to cool itself, similar to a person sweating. This leaves less water for photosynthesis.
The strong light and higher temperatures also evaporate water from the soil. This can further dehydrate the plant.
High-intensity or bright light can also cause leaf scorch, which is essentially the plant version of sunburn.
Just like duration, the needs of your plant will depend on the species. Some plants require intense light, while others can die from too much intense sun.
Measuring Intensity and Duration
If you want to get technical and precise, you can purchase a light meter to determine exactly how much light your plant will receive in a given area.
However, this isn’t really necessary. All you really need to do is think, and see, like a plant. Get on the level your plant would be in the area, and take a look at the quality of light.
Types of Light Intensity
There are three basic types of light intensity. Type 1 is direct sun. This is preferred by some plants, including those native to deserts. Other plants can’t tolerate a lot of direct sunlight.
If the plant is outdoors in full sun, or the light is streaming in from a window, this is likely direct light. In simple terms, if your plant has a direct line of sight of the sun, it’s considered direct sunlight.
Type 2 includes filtered or reflected sun. Filtered or diffuse sunlight means that the sun is partially obstructed. Trees and sheer curtains provide this type of light.
Reflected sun is when the sun is reflecting off an object. If your plant sees the sun in a mirror or shiny surface, this is reflected sun.
Type 3 is skylight. This means your plant doesn’t have a view of the sun, but they do see the sky.
Most houseplants do well with bright indirect light. This means the area will be well lit, but without your plant receiving direct sunlight. Type 2 and 3 light can qualify as bright indirect light.
Measuring Light Duration
Measuring light duration is fairly straightforward. You’ll simply need to monitor the area for a day or two, and note how long the plant is exposed to light.
If you want to be specific, you can break it down into types of light as well. A houseplant may receive two hours of type 1 sunlight, and 4 hours of type 2 light, for example.
In most cases, you don’t need to be this specific. Just ensure that the overall duration of light is within your plant’s needs.
When determining how much light your plant is getting, remember that these measurements will change over time. Your plant will get much more light in July than in December. You may need to adjust where your plant is to give it optimal light all year round.
8 Signs of Too Much Light On Your Plant
Now that we understand the two components of light, let’s take a look at the signs your plant is getting too much.
1. Yellow Leaves
The first sign of a plant getting too much light is often yellowing of the leaves. Typically, this begins with yellow patches on the leaves. The leaf margins will also turn yellow. Eventually, the entire leaf will turn yellow.
This can look similar to other issues, including nitrogen deficiency. However, there are some noticeable differences. First, if leaves turn yellow due to nitrogen deficiency, the leaves will usually pull off easily. Leaves that yellow due to too much sun will not be easily removed.
Another difference is that the veins in the leaf will remain green, while the rest of the leaf becomes yellow.
2. Droopy Leaves
Droopy leaves are another sign something’s wrong. Leaves droop when they are unhealthy. Dehydration, root rot and overwatering can also cause the leaves to droop.
However, if too much sun is the problem, you may also notice the leaves look dry.
3. Crispy Leaves
Leaves can become crispy if your plants are getting too much light. This can be due to the light itself, or dehydration due to dry soil. In addition to a crispy appearance and texture, they will sometimes curl in on themselves.
4. Brown Patches
Your plant’s leaves may also turn brown. This can include brown patches, or the entire leaf turning brown. This typically occurs if there’s too much light intensity.
It causes burns on the leaves. This kills the cells in the leaf, causing it to turn brown. Unfortunately, these leaves can’t be repaired. However, you can prevent further damage by limiting sun exposure.
The light can also fade the plants’ foliage or blooms.
You may have seen the sun fade clothing or even furniture. The sun’s light can bleach your hair, making it lighter. It can also bleach your plant, causing it to look lighter or not as bright.
6. Feeling Heated
One of the simplest ways to see if your plant is getting too much sun is to feel it. This is best done during the warmer part of the day, when the sun is streaming down on the plants.
Feel the plant’s leaves. Does it feel uncomfortably warm? If the plant is hot, it’s probably getting too much light.
7. Dry Soil
If your plant’s soil is dry, particularly soon after watering, this may be due to the light. As mentioned previously, the sun brings heat. This heat causes the soil to dry out.
Of course,the soil will dry out eventually, no matter the light conditions. However, if you are struggling to keep your plants’ soil moist, it may be getting too much light.
8. Slow or Stunted Growth
If your plant isn’t healthy, its growth will slow or stop completely. It takes energy and nutrients for the plant to grow. If they are experiencing hardship, they will put their energy into surviving instead of growing.
Different plants grow at very different rates. This can make it difficult to determine if your plant’s growth has slowed or stopped, at least in the short term.
However, once you are accustomed to your plant’s regular growth cycle, changes in its growth can clue you into potential problems, including too much light.
Determine How Much Light Your Plant Needs
You know something is wrong with your plant, and you are wondering if too much light is the culprit. The best way to confirm that too much light is the issue is to compare how much light your plant is getting with how much light it actually needs.
Determining how much light your plant needs, and if it’s getting the right amount, can also help you determine if too much light is what’s harming your plant.
Start by learning how much light and the type of light the plant needs. Then, monitor the light conditions where the plant is for a day or two. Most houseplants thrive in bright, indirect sunlight but it will depend on the type of plant you have.
How many hours of daylight are they exposed to? Does the plant get hot to the touch, indicating strong intensity? Are they in a curtained window, which helps to diffuse the light, or directly in sun for the duration of the day?
Putting It All Together
When determining if your plant is getting too much light, it’s important to look at all of these symptoms.
If your plant is doing well, but the plant is hot to the touch, you probably don’t need to give it less light. However, if your plant is struggling, you’ll need to cut down on the amount of light it is getting.
You should also consider how well the plant’s needs line up with its current conditions.
You are now certain your plant is getting too much light. Now what do you do? There are a few ways to decrease the amount of light your plant is getting.
If your plant is in a pot, the easiest way to cut down on sun exposure is typically to change its location. If it’s an outdoor potted plant, find a spot that has shade, particularly in the afternoon when the sun is strongest.
If it’s an indoor plant, consider moving it farther away from the window, or moving it to another window. South-facing windows get the most light, while north-facing windows get the least.
West-facing windows get afternoon sun, and receive the most light after south-facing windows. East-facing windows get a bit more light than north-facing windows.
If moving your plant isn’t an option, or you enjoy your plant where it is, you’ll need to block some light. A shade blanket can be a lifesaver for outdoor plants.
They are netting that blocks about 50% of the light. This allows your plants to get the sun they need, without getting too much light. For indoor plants, a curtain works well.
Sheer curtains work well for diffusing light. If your plant is getting damaged, however, an opaque or thick curtain may be required. You can pull the curtain back, allowing the plant to get the morning sun, and then cover the window in the afternoon.
Shades are another option. Just like curtains, you can leave the window open for part of the day, and then pull down the shade. Some shades will block some light, while others block nearly all light.
Summing It Up
Light is essential for plant life, but too much can harm or even kill them. If your plant is wilting, has yellow or brown leaves, or stunted growth, too much light may be the issue.
If your plant is getting more light than is recommended for them, this can give you confirmation that too much light is the problem.
You may need to move your plant to a new area, put up a curtain, or provide your outdoor plant with shade.