What Can Happen to Your Plants With Too Much Light?

Light serves as food for all plants, and helps them grow – a process referred to as photosynthesis. But what can happen to your plants with too much light? Just like drinking an extreme amount of water can cause hyponatremia, commonly referred to as water intoxication, too much light, as a  life-source needed for all vital plant functions, can be detrimental to your plant’s overall well-being.  

Shedding a considerable amount of light on your plants can cause light burn, and affect them in several ways, most notably when they start to exhibit signs of stress on certain areas of the leaves, causing them to appear burnt. The leaves of the plant when affected by light burn will develop yellow or brown spots with burnt tips, resulting in little or no presence of THC among other issues.

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Key Signs of Light Burn 

When you hear growers speak of “albino cannabis” or “white cannabis,” know that it is not a good thing, but rather means that your plants aren’t in the best of health. It is important to understand the signs of light burn, because some of them can be easily confused for other issues such as a few different nutrient deficiencies such as lack of nitrogen.

Apart from showing change in color in the affected areas, the leaves of cannabis plants can turn yellow and cause the buds to turn white. The difference between light burn and nitrogen deficiency is that the former displays yellow leaves at the top at spots where the foliage is closer to the light. The latter affects the lower, older leaves first and then the newer ones at the top resulting in the shedding of leaves.

When grown outdoors, cannabis plants usually prefer direct sunlight, which is probably the biggest reason why most of plants grow to be healthy in good light light conditions under the correct artificial light.  

How Much Light Can a Cannabis Plant Get Outdoors? 

To harvest a well-nourished yield, farmers through years of trial and error try have tried to create a way that will replicate the sun or better yet – improve on it. This is one of the biggest reasons why indoor growers rely on timers to artificially replicate this light-dark cycle.

Now that you know the consequences of directing too much light on your plants, you’re probably wondering how much light using grow lights do your plants need? To understand better, it is good to understand the amount of light a plant can receive when grown outdoors.

When grown in locations that receive a considerably low level of sunlight, cannabis plants could get a minimum of 30,000 to 35,000 lx on a bright, sunny day. These numbers could plunge to 8,000 lx on overcast days, and contrarily can rise to as high as 80,000+ lx on peak summer days in the desert.

The good news is that with the right soil, temperature, etc., cannabis can usually survive in all the aforementioned scenarios. However, the desirable amount of sunlight for a cannabis plant depends on the type of plant and strain.

But the ideal levels for most cannabis plants is between 30,000 and 75,000 lx for the vegetative stage, and between 50,000 and 90,000 for the flowering stage. When all the needs of a cannabis plant are satisfied, getting a sufficient amount of sunlight means that it will grow well, and won’t be affected by any other factors except its genes.

Cannabis plants that receive lower levels of light than the ideal range will in most cases take longer to develop or grow skinny stems and buds. And plants that receive a higher level than the ideal light range will typically experience light burn, heat burn or nutrient issues.

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How to Set Up Indoor Grow Lights

Plants that gradually get higher levels of light tend to absorb more nutrients via their roots especially in the case of liquid or powdered nutrients. This is mainly because cannabis plants are thirstier when its sunny out or receive the right amount of indoor light, hence tend to drink more water.

And when they do take in more water via the roots, they get more nutrients as a result. It is rare for your plants to experience light burn when outdoors, because they will never be too close to the sunlight.

So, if you think your plants are getting too much light indoors, the best thing to do is move the lights further away from the top of the plants. But you also need to maximize the amount of light your plants receive from the grown lights, so you must keep them as close as possible and just far enough to not cause damage to them, especially from heat if the light source is generating a lot of radiant heat as with HPS light compared to and LED source.

The only and free way to determine the distance to place your grow lights is ask the person or manufacturer who made them. Given that each LED light model is different, they need to be set up at different distances from your plants.

If you can’t get a hold of the manufacturer user guide or the person who made the lights, performing a hand test is another option. Although not accurate, the hand test (only effective on non-LED lights) should give you a pretty good idea of the amount of heat and energy your plant is receiving from the lights.

To get started, place your hand near the plant for roughly 30 seconds, and if it feels extra warm means that the lights need to be moved further away. If you’re aren’t using LED lights, a lux meter can be used to check the level of light in a specific spot to help you determine whether your plants are getting the right amount of light.


Now that you know what can happen to your plants with too much light, you should take the necessary steps to keep them at the right temperature at all times for optimal growth, and the best yield.

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  1. When expanding cannabis with coco, good quality coco coir makes an enormous difference, Primarily relating to root growth. For beginner growers, A 3-to-a person coco to perlite combination is usually recommended as it needs considerably less watering frequency and holds humidity and nutrients much better.

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