Opening your grow tent or inspecting your outdoor plants only to find blackened leaves and buds can be alarming. But before you prune away the infected parts and trash your crops, it’s important to understand the possible causes behind black weed
In some cases black discoloration signals a serious problem like mold, mildew or pests. However, black cannabis can also occur naturally thanks to genetics and environmental growing conditions.
So how can you tell if black weed is a cause for concern or just a cool color variation? This guide breaks down the science behind black cannabis and helps diagnose what’s causing those ominous dark tones.
What Causes Black Marijuana?
Cannabis plants produce chlorophyll to absorb light energy and power photosynthesis. This gives them their classic green hue. However, marijuana can also contain other pigments that alter its coloration.
Anthocyanins
Anthocyanins are water-soluble plant compounds that create blue, purple, and red tones Cannabis strains with genetics that promote anthocyanin production can develop strikingly vivid purple buds
In some cases, colder temperatures and shifts in pH can make these purple anthocyanin pigments so concentrated that the buds appear nearly black. This natural genetic expression and reaction to the environment causes black weed.
Necrosis
If your cannabis leaves or flowers turn black and feel dry or crunchy to the touch, it’s likely necrosis – the death of plant tissue. This can have several causes:
- Nutrient burn from too much fertilizer
- Underwatering
- Overwatering
- Light or heat stress
While genetics and environmental conditions cause natural black discoloration, necrosis that leads to black, dead plant matter demands quick action to diagnose and resolve the underlying issue.
Mold
Excess moisture promotes mold growth. Poor air circulation, humidity control issues, and overwatering make cannabis vulnerable to harmful mold like botrytis (bud rot) and powdery mildew.
These fungal infections initially produce white patches on leaves or flowers. But as the mold matures and spores spread, it can turn buds black.
Pests
Bugs are another common culprit behind blackened cannabis. For example, thrips and spider mites cause streaks or dots of black discoloration from the wounds and waste left behind as they feed.
Aphids secrete sugar-rich honeydew that can foster sooty mold growth leading to black patches on leaves and buds. Spotting the insects themselves makes identifying pest problems easier.
Light Burn
Too much intense light can scorch cannabis leaves, causing burnt black edges or spots.LED grow lights in particular can inflict light stress if positioned too close to the canopy. But even outdoors, excessive sunlight coupled with heat and drought stresses cannabis and leads to black leaf margins.
Deficiencies
Lack of essential nutrients causes distinctive discoloration and deformities. For instance, calcium and magnesium deficiencies turn leaf tips and margins black and eventually lead to necrosis.
A potassium deficiency produces dark splotches and curled, dead leaf edges. Identifying and correcting nutrition issues resolves the problem and prevents blackening.
Is Black Weed Bad?
Black leaves or calyxes certainly look ominous, but black weed itself is not necessarily bad. When genetic anthocyanin expression causes the natural color shift, it has no adverse effects on cannabis health or potency. These unique dark marijuana strains are safe to enjoy.
In some cases, mild environmental stresses prompt anthocyanin production leading to dark purple that borders on black. As long as the overall plant remains healthy, some anthocyanin rich calyxes are not a problem.
However, black discoloration from pests, mold, disease, nutrient problems, overwatering, and other stresses indicate underlying issues that will degrade overall plant vigor and quality if left unchecked.
How to Fix Black Weed Problems
Here are some tips to resolve the most common causes behind black cannabis:
- Pests – Use organic insecticidal soap or introduce beneficial predators like ladybugs.
- Mold – Improve air circulation and humidity control. Remove infected areas.
- Necrosis – Flush plants and correct nutrient levels.
- Underwatering – Give plants a thorough, slow soak to fully hydrate.
- Overwatering – Allow soil to dry out more between waterings.
- Light burn – Raise lights or use a canopy barrier to diffuse intensity.
- Deficiencies – Give plants supplements or nutrient solutions tailored to their needs.
Promptly identifying and addressing what causes blackening prevents it from spreading and ruining your entire harvest.
Growing Dark Weed Strains
While problematic causes of blackened weed should be avoided, growing intentionally black cannabis strains offers an exotic outcome for those seeking unique bud bag appeal.
To safely develop the darkest possible phenotype expressions:
- Select genetics prone to anthocyanin production – The Black, Black Domina, Purple Punch
- Lower temperatures to around 65°F during lights-off periods
- Use larger swings between daytime and nighttime temps
- Allow soil pH to rise to 6.5-7.0 (but not above)
Ample anthocyanin concentration from the proper genetics and environment leads to stunning shades of purple so dark they border on black.
What is Black Weed? A Sign to Take Action
Black discoloration in cannabis can indicate:
- Genetic Expression – Unique anthocyanin pigments
- Problems – Mold, mildew, pests, disease, stresses
While natural genetic anthocyanin production causes some safe black weed variations, the majority of cases are warning signs.
Inspect plants closely to diagnose what underlying problems prompt blackening. Then take prompt action to correct issues and protect your harvest. With quick troubleshooting and treatment, minor cases will not ruin the entire crop.
So while black leaves or flowers may look scary at first, they act as helpful visual cues pushing you to dial in optimal grow conditions and remedy anything hindering plant health. Address problems promptly and you can still end up with vibrant green buds and an abundant harvest.
Anthocyanins and How They Work
Anthocyanins are of the flavonoid group of the phytochemicals. Despite the similarity of their name to cyanide, they are actually very good for human health and nutrition. This is what anthocyanins do for the plants they are in: they give them color. Think of blueberries, blackberries, strawberries, and grapes. They are a strong pigment, giving the plant that produces them its dark, rich hue. The more anthocyanin that is produced, the darker the color the plant or berry will be. They are almost invariably produced by the plant as a response to stress, either chemical or temperature. Ever heard that berries taste better after being frozen? That would be the anthocyanins. The same things anthocyanins bring to berries and wine, they bring to black cannabis.
Some of the proposed health benefits of anthocyanins to humans include:
- Improved visual acuity
- Cancer prevention due to inhibition of tumor growth
- Reduced inflammation
- Anti-oxidation
- Increased neural function
All of this sounds great for people, but what do they do for the plant? The fact that they usually start to grow when it gets colder is a clue. Anthocyanins are natural antifreeze. They help the plant keep its water when it’s cold outside, when the water would normally freeze and form crystals on the outside of the plant. This also explains why draught is a trigger for anthocyanin production. Additionally, they let the plant soak up blue and green light, which helps it survive in low light. That’s pretty handy in northern climates. There is no need to make an antifreezing agent or keep water in plants when the weather is warm and conditions are good. This means that the plants become lighter in color or greener and taller.
The Origin of Black Cannabis
Nearly all cannabis plants that are grown in warm climates are bright green. When these same types of cannabis plants are grown in cold places, though, some of them turn darker. Not all of them, mind you, just a few of them. If you breed these two darker plants together, the babies they have will be even darker as long as they are kept and grown in a cold place. Some also become darker when experiencing draught or adverse soil conditions. This sort of pattern is a clear signal that it has to do with genetics. The rarity of the trait indicates that it is recessive.
The mathematics behind the genetics of black cannabis are not fully understood yet. On the other hand, the fact that plants always get darker in extreme temperatures shows that the genes that allow this happen are good for them in some way.
But why does it only turn that color in the winter? What’s the point? How does it happen? The answer is a chemical called anthocyanin.
The dark side of my weed addiction
FAQ
What color is bad weed?
Is black weed bad?
What does it mean if weed is dark?
What does black out mean weed?
What causes black spots on cannabis leaves?
Pests such as aphids, thrips, and spider mites can lead to black spots. Furthermore, fungal diseases like Septoria leaf spot and bacterial diseases can also cause these spots. Lastly, deficiencies in phosphorous or nitrogen can manifest as black spots on your cannabis leaves. 2. How can I prevent black spots from forming on my cannabis plants?
What are the causes of black urine?
Alkaptonuria, or black urine disease, is a very rare inherited disorder that prevents the body fully breaking down two protein building blocks (amino acids) called tyrosine and phenylalanine. It results in a build-up of a chemical called homogentisic acid in the body. Most common causes of black urine are Dehydration/Hemolytic anemia/Urinary tract infections/Hepatitis C and certain food and medication.
What are black spots on weed plants?
Among the multitude of things a grower needs to watch out for, one common and often unnerving discovery is black spots on weed plants. This unexpected sight, similar to a pothole on a smooth road, disrupts the otherwise lush green texture of the plant. These black spots are more than just unsightly; they carry implications for your plant’s health.
How do you know if a cannabis plant has black spots?
Early signs of black spots on cannabis plants can include discoloration or darkening of the leaf surface. The appearance of small, black or dark brown spots can also be an early sign. It’s important to check your plants regularly for these signs to ensure early detection and treatment.
Why are my cannabis leaves turning brown?
Unstable pH values can affect the nutrient intake of your cannabis plants, resulting in brown spots appearing around the middle and lower parts of the leaves of your cannabis plants as a sign of stress. Learn more about PH Fluctuations An excess of phosphorus will result in mottled or mosaic-patterned leaves.
What causes black spots on leaves?
In the battle against black spots, diseases, especially fungal infections, pose a serious threat. The fungus known as Leaf Septoria, also referred to as yellow leaf spot, is one such adversary. It usually shows its ugly face as yellow and brown spots on the lower leaves during the flowering phase before spreading its destructive influence upwards.