What causes nutrient burn? Is it a particular nutrient or something else?

[NebulaHaze]

Everyone hates getting nutrient burn. But what causes it? We have all heard that nutrient burn is the result of too-high levels of nutrients, but which nutrients, in particular, are to blame?

Examples of nutrient burn






We know this these symptoms are the result of the marijuana plant uptaking too high levels of nutrients, but which nutrients?

Maybe we can figure out by the process of elimination:

• It isn't Nitrogen - too much Nitrogen causes dark leaves and tips that curve down, but you can get very dark leaves without any tip burn.
• It probably isn't Calcium, Magnesium or Iron - If you read the label of CaliMagic, which contains Nitrogen, Calcium, Magnesium and Iron. It claims that it can be used to help prevent tip burn. That's not definitive proof, but that does seem to indicate those nutrients are probably not the main culprits causing tip burn for most growers.

What's left?

• Of the major plant nutrients, it seems like the remaining culprits are Phosphorus, Potassium, Sulfur, Molybdenum, Boron, Copper, Manganese, and Zinc. Could an overabundance of one of these be causing the nutrient burn symptoms seen above?
• Could nutrient burn possibly be caused by something else, or some combination of factors? (read the update at the bottom of this post for other potential factors)

To make things more confusing, sometimes you get symptoms that look a lot like nutrient burn, but are actually the signs of a nutrient deficiency or other growing problem.

This is actually a copper deficiency, which was caused by the pH being too low



These edges are actually the symptoms of a potassium deficiency






These are light burned leaves. The symptoms were caused by an LED grow light being too close.



What specific nutrient or compound do you think causes nutrient burn in cannabis plants? What have you done that resulted in tip burn on your leaves?

~~~~

Update: Based on what I've learned since I first made this post, it seems that nutrient tip burn on cannabis plants could potentially be caused by...

• Too high levels of nutrients (which is what nutrient burn is usually blamed on)
• Improper watering practices (letting growing medium dry out too much between waterings, causing root stress when the amount of water at the root zone changes too quickly)
• Big changes in the level of available nutrients at the roots (for example alternating between nutrient water and plain water in a soilless medium)
• PH being too high or low (causing nutrient deficiencies with symptoms that can appear to be tip burn)
• Environmental factors like high temperature, low humidity, and intense light levels
• Nutrient ratios - In some crops like lettuce, low Calcium levels within the leaves increased the chance of seeing tip burn, so potentially nutrient ratios could have an effect? Though I haven't seen much discussion about this with cannabis plants, and as a crop, growing cannabis very different from lettuce in a lot of ways! It does seem worth examining nutrient ratios though.

What is everyone's thoughts on each factor? Which ones make a difference and which ones don't? Am I missing anything that can cause tip burn?

 

[Chefbjy]

Very intresting. I've seen tip burn happen to plants going into fresh ffof soil no nutes added yet. Also have seen it when I wasn't monitoring ec but couldn't say what was so abundant to cause tip burn. Using gh maxi series I've found that too much of maxi grow will cause it 10-5-14 with the rest of the line that mostly contain p and k. But it would be intresting to find of out of it was the other nutrients such as sulfur zinc or copper.

 

[Canuck147]

I have used fancy molasses recently (couldn't find organic-unsulfered) and the very ends of my leaf tips are yellowed.

 

[D.A.A.S.69]

I couldn't tell what nutrient, is the culprit, but I know it changes from plant to plant, some can take regular doses, and show no symptoms, and others it shows up the next day, with the same dose.

 

[DrPhoton]

Its not a particular nutrient but the effect of over concentration of solutes in the root zone which inhibits water uptake through osmosis. Nutrient burn is not from toxcicity within the plant, but the result of osmotic stress causing some form of dehydration that starts from the outer edges of leaves.

Campesino may be able to elaborate more on this.

 

[oldjarhead100]

Nebula you know we will be debating this for awile lol

 

[Sheesh]

I think Dan has a good point. If nutrient burn is related to the edges starting to dehydrate, would foliar feeding help correct it?

 

[Potted]

I was always under the impression that a little nute burn was not a bad thing? In light of what Dan said and the fact that after watering (next day) I get tip burn. Could it b that the tip burn is caused by osmotic stress?

 

[Weed Pharma]

I use to know this one!

Pic #1
I recall the browning tips curling up is significant in the diagnosis.

Pic #2
The leaf location on the plant and the plants growth phase is significant, here.

ps- I have leaves like Pic #2 on most of my grows during flower.

 

[Chefbjy]

Do you think dentrification could impact this as well?

 

[growmore]

I think a lot of the problems we see with nutrient burn is a breeder created problem. A breeder will use a particular ratio of NPK, PH ect at there own ppm strength in a particular environment and as a buyer of their seeds we don’t have any idea as to what they use.
This is really just something called hidden selective breeding. Hidden because a breeder will select plants that produce the traits that they are breeding for but along with that they also select the best performing plant with their growing system.
If they were bred growing in soil or coco using low nutrient levels then you would not expect them to grow as well at higher levels.
Similarly you would not expect a plant bred for soil or coco to grow as well in hydro or visa versa.

 

[NebulaHaze]

That's so interesting! Do you think it was the fancy molasses that caused the tip burn? Have you ever had trouble with unsulfured molasses? Maybe nutrient burn can be caused by too much sulfur (which I think gets added to the fancy molasses to change its flavor).

That cola looks amazing, by the way!

 

[NebulaHaze]

A little bit of nutrient burn won't hurt anything, but if it goes unchecked it can get really bad! I'm also interested to learn more about how it may be affected by osmotic stress. That's something I'm going to look into.

 

[NebulaHaze]

Interesting, I want to learn more! Do you know of any studies or research I can look at? I have noticed that plants are far more likely to get nutrient burn if it's hot and they're drinking a lot of water so it makes sense the nutrient burn has something to do with water uptake. If EC levels are kept stable, I wonder if some types/forms of nutrients are more likely to cause nutrient burn than others.

 

[NebulaHaze]

That's an interesting thought. For example, if a breeder only uses hydroponic setups during their breeding program, after a few generations of selectively breeding the most vibrant plants in their setup, will those strains tend to do better in hydro on average? I could definitely see how the breeder's growing environment could affect which plants do well, and therefore which plants they choose to breed. Same with the nutrients they use.

 

[growmore]

Whenever you breed in any environment or system, those conditions will influence how the plants grow and therefore influence which plants you pick to breed with.
I breed outdoor strains with high nutrient levels 1100 ppm in veg and 1400 in flower. These plants don’t like inside conditions and simply don’t grow well. They are no longer anything like the original genetics I started with because of my selection of the parent breeding stock.

 

[Canuck147]

Yes - must have been the fancy stuff I used. Unsulfered works best.
And thanks.

 

[NebulaHaze]

So it seems that nutrient tip burn on cannabis plants could potentially be caused by...

• Too high levels of nutrients (which is what nutrient burn is usually blamed on)
• Improper watering practices (letting growing medium dry out too much between waterings, causing root stress when the amount of water at the root zone changes too quickly)
• Big changes in the level of available nutrients at the roots (for example alternating between nutrient water and plain water in a soilless medium)
• PH being too high or low (causing nutrient deficiencies with symptoms that can appear to be tip burn)
• Environmental factors like high temperature, low humidity, and intense light levels
• Nutrient ratios - In some crops like lettuce, low Calcium levels within the leaves increased the chance of seeing tip burn, so potentially nutrient ratios could have an effect? Though I haven't seen much discussion about this with cannabis plants, and as a crop, growing cannabis very different from lettuce in a lot of ways! It does seem worth examining though.

What is everyone's thoughts on each factor? Which ones make a difference and which ones don't? Am I missing anything that can cause tip burn?

I was always taught to alternate between nutrient water and plain water when growing cannabis, but if better growth can be achieved by giving nutrients every watering without causing tip burn, that's definitely something I'd like to get to the bottom of! What about soil? Obviously, you can avoid tip burn even when alternating between plain water and nutrients in coco, as there are several plants in my tent right now that have been alternating and don't have tip burn, but I could see how it might make plants more susceptible. Another thought is hydroponics - you can get tip burn in hydroponics, which obviously doesn't have to do with watering practices, but I could see it being triggered by some of the other listed factors like high levels of nutrients, pH, environment, etc.

What do you think? What has been your experience?

 

[Sheesh]

Hey Nebula, cool topic. I'm on my second coco grow and I followed Campesino's advice to buffer the coco and have no water only days in the schedule (except I did flush with FlorKleen when I flipped to 12/12). The plants are in week 1 of flower and the plant health is excellent with no nute burn to date. All of my soil grows and my first coco grow had minor tip burn by early flower. So, my experience supports bullet # 3 as a possible cause of tip burn (alternating between nutrient water and plain water in a soilless medium).

 

[Chefbjy]

Maybe not so much of an excess if ph is unbalanced in soil (organics) depending on fertilizer used? I'm wondering about tip burn on my organic grow the only thing I can think of is the epson salt. How does salt build up in organic mediums? It's not heavily amended, though I did top dress with fish bone meal and noticed it shortly after.

Thinking environment and watering have a lot to do with it as you stated above. Not too sure about it though. Just a current experience I'm dealing with. Debating if it's an early sign of k deficiency or tip burn.