weed light burn

Cannabis Light Stress And Light Burn

Dealing with cannabis light stress and cannabis light burn can be very stressful – especially if it’s your first time going through it. However, with the right precautions and growing know-how, it’s possible to identify light stress and bounce back even from the worst cases! Let’s learn how to do it.

What Is Cannabis Light Burn And Light Stress?

Cannabis light burn is the extreme case of cannabis light stress, which occurs when your plant gets more light than it needs for healthy growth. This can lead to bleaching of certain parts of the plant such as the leaves and flowers. However, light stress/burn can manifest itself in many ways, including the browning and drying out of leaves, giving them a dry, crispy texture.

Easy-To-Grow Cannabis

Depending on your light source, there are different levels of associated danger from light and/or heat stress. Depending on how much heat your lights emit, the safe distance to hang them depends partly on the former factor as well as others such as plant maturity, level of airflow and type of light (HPS, CFL, LED, etc.). Before starting any grow, it’s therefore important to ensure you’ll be in a position to provide your plants with exactly the right conditions in which to properly grow.

Dangers Of Cannabis Light Burn At Various Stages Of Lifecycle

Simply put, the dangers of cannabis light burn are loss of potency, a worse appearance due to burning, and loss in quality and depth of terpene profile. Of course, the biggest danger would be a significant reduction in final yield.

The impact of light burn varies depending on the maturity of the plant, but this is the biggest issue for seedlings that can be easily burned by the high intensity of high-power growing lights. Next are plants in the vegetative stage which have established their ground and are self-supporting but are still susceptible to the dangers of powerful lighting. With respect to recovery, the greatest danger is for plants in the flowering stage, where it’s easy to overlook the impact of light stress as your plants change into their fall colors.

Symptoms Of Cannabis Light Stress And Light Burn

The following are symptoms of cannabis light stress and light burn:

  • Bleaching of buds
  • Browning of leaves
  • Leaves curling upward (“taco”-ing)
  • Discoloration of leaves but veins are still green
  • Irregular growth pattern

If your plants are receiving too much light and are under stress, they will exhibit some or all of the symptoms listed above.

Are There Ways To Fix Light Burn?

Unfortunately, if parts of your plant have experienced light stress, especially to the point of light burn, then no amount of TLC will be able to bring them back. However, it’s possible to take remedial action by making changes to the amount of light your plant receives to a safe level and not inducing any further unnecessary stress.

Avoiding Light Stress And Light Burn – Learn How Much Light Is Too Much For Cannabis

If you have the resource to invest in a lux meter, it is highly recommended you do so! Not only is this useful in assessing whether your plants are getting too much light, but it can also identify areas receiving insufficient light. This is particularly important for commercial growers, as it maximizes bud production. Lux meter readings are given in lux/m 2 and should fall in the following ranges based on plant maturity:

  • Vegetative: 30,000 – 70,000 lux/m 2
  • Flowering: 50,000 – 90,000 lux/m 2

Set The Correct Height For Your Lights

Also, if you don’t have a lux meter, but still want to avoid light stress, it’s important to set the correct hanging height for your lights, especially as modern growing lamps tend to have high power ratings that can easily cause damage to cannabis plants irrespective of maturity. To check if your lights are hanging correctly:

1) Test the level of heat on the back of your hand at canopy level.

2) If it’s irritating at all, lift the source of light higher, and repeat the same test.

3) Do it again until the temperature feels comfortable and not irritating.

While this may seem basic, it’s a tried and tested way of making sure your plants get the light they need without overdosing them!

Ran Out Of Height? No Problem!

Ideally, one should never encounter this problem. With the right amount of planning, it’s possible to ensure your plants never grow too large for your space. However, things don’t always go to plan – especially when growing a plant from seed. If you’re limited for height, use low-stress training from 3-4 weeks into plant growth.

If your plants are growing too close to your lights and you don’t have any vertical space left to raise them, you can supercrop the plants to stunt their growth and keep them intentionally small. While supercropping is useful for this, it can also be used strategically to boost THC levels! This occurs when cannabis plants ramp up production of THC as a defense mechanism whenever they feel under attack.

Small Cannabis Plants

Here are some frequently asked questions that may help you better understand light burn.

How long does it take cannabis to recover from light burn?

While the damage brought on by light burn is permanent, your plant can still recover. Depending on its maturity, a plant may have enough remaining time in its lifecycle to recover from damage, whereas for plants that experience light damage toward the end of their life, there is very little that can be done. As long as you catch the problem while it’s not too late, cannabis plants can recover from light stress in as little as 5-7 days, although most plants take around 10 days to show physical changes.

Can light stress cause cannabis plants to change sex?

Cannabis plants can change sex as a result of environmental factors, and light stress is no exception. Plants that experience light/heat stress therefore have a far greater likelihood of turning into hermaphrodites than those that don’t, so it’s entire possible for this to occur as a result of light stress.

The following symptoms can cause cannabis plants to change sex:

  • Changes in photoperiod
  • Changes in temperature
  • Over-watering/feeding

Light burn or nutrient deficiency – how do I know?

When something goes wrong during a grow, most growers think about water or nutrient-related issues. If you think your plants are experiencing light burn, how do you know it’s not a nutrient deficiency? Well, while the symptoms of the two can appear to be very similar, it’s possible to easily tell between the two by considering the symptoms your plants are showing. It’s unlikely you’ll experience light burn-like symptoms due to excess of any of the nutrients described below, but it’s a possibility nonetheless (particularly with phosphorus).

This Is Not Light Stress But Nitrogen Deficiency, If…

  • You notice discoloration of leaves (starting from the bottom of plant and moving upward)
  • Leaves have droopy appearance without luster
  • Leaves falling off (coming off without much resistance)

This Is Not Light Stress But Calcium Deficiency, If…

  • You see irregular, yellow-brown spots on leaves
  • Lower leaves start curling

This Is Not Light Stress But Phosphorous Deficiency, If…

  • Leaves have blue/green tinge
  • There are dark, copper-colored patches on leaves
  • Leaves wither and curl at the tips

This Is Not Light Stress But Magnesium Deficiency, If…

  • You notice the loss of older leaves (withering and dropping)
  • Leaf veins turn yellow
  • There are irregular rust spots

If you’re concerned about nutrient deficiencies causing changes in the appearance of your plant, flush the rootzone with 15-20 liters of plain, pH’d water to remove any build-up at the bottom of your growing medium.

Marijuana Light Burn And Stress: The Bottom Line

Let’s consolidate what we’ve learned. After reading about light stress and the dangers of light burn to cannabis plants, you should know what to look out for when assessing whether your plants might be receiving too much light. If you want to harvest large, dense buds with a beautiful appearance and fragrant terpene profile, ensure your plants are free of any signs of light burn by checking them frequently. This should not only help avoid light burn, but also highlight any other problems through the extra attention!

Cannabis light stress & burn may seem innocent, but it can be deadly to your harvest. Read on to learn about dangers of light stress in weed and how to avoid and fix it.

How to prevent and treat cannabis light burn?

Light burn or light bleaching is a serious problem if you’ve got a got a room full of cannabis plants. Light serves as food for the plants, but it can also be an issue if it goes overboard. Think of it this way – humans need food for energy, but what happens if you eat too much? Yep, you’ll have several problems from obesity to diabetes.

Similarly, cannabis plants use light as food, but if you install too many lights and hang them too close to the plants, you’re asking for trouble. If you notice your plants struggling, keep reading to figure out how to prevent and treat cannabis light burn.

What is a light burn?

ight burn is nothing but light bleaching. You’ll notice that the leaves too close to the light turn white or look bleached. Plants growing outside cannot suffer from light burn because the sun is too far away from the earth to burn the plants. Cannabis has evolved for centuries and has adjusted to the sunlight enough to not get burnt.

But, light burn can happen indoors. The leaves and even the buds begin to look white or burnt when the lights are hung too close to the plants. The heat is so high that the plants cannot tolerate it. White buds look amazing when you look at them, but it’s a sign that the buds are damaged.

Since the light is too close to the buds, the resin along with the cannabinoids are destroyed. You probably already know that heat kills plants, and buds are no exception. In fact, not only will the buds be useless for both medicinal and recreation users, but the taste goes for a toss too. And the fragrance deteriorates as well.

Yellow leaves can also indicate light burn at times. But, do not get confused between nitrogen deficiency and light burn because they look the same. With nitrogen deficiency, though, yellowing of the leaves start from the bottom and move towards the top. Also, the leaves are limp and fall off from the plant without any effort. On the other hand, if they are suffering from light burn, the leaves feel crispy and are harder to pluck from the plant.

Leaves turning brown and crisp is an indication of light burn too. It’s a combination of heat and too much light that fries the leaves and render them useless to the plant.

How to prevent light burn?

Prevention is far better than cure, they say. Thus, you must try to prevent light burn rather than trying to cure it. First off, light burn depends on the type of light you’re using. For instance, a CFL hung even 10 inches away from the plant will not damage the plant. The same applies to fluorescent or T5 lights because they aren’t that powerful and don’t emit a lot of heat. However, HID and LED lights positioned even 10 inches away from the plants can kill them.

Secondly, determine the wattage of the lighting you’re using. For example, a 50W LED light may not be too harmful, but a 1000W LED will have disastrous consequences if you place it too close to the plants. HID lights are too powerful even if the wattage is low. Another problem is that they emit way too much heat that can be unbearable to the plants.

Having said that, remember that you can’t hang the lights too far away either. If the plants are very far away from the light, they will not have enough food to grow properly! You can consider both HPS and Metal Halide lights in the same category. Here’s a tip to help:

Light burn or light bleaching is a serious problem if you’ve got a got a room full of cannabis plants. Light serves as food for the plants, but it can als