Nitrogen tox?

Hi all. Usually always have issues with my grows with over feeding, currently running 2 auto cheese from fast buds in bio biz light mix. With added perlite. This run I was planning on not feeding untill around week 3 or 4 as I generally get alot of burn so thought Ill give only water and PhD water to 6.4... I've now noticed some browning on the tips of the new growth. How can this be? Surely light mix isn't hot?

Looks like it might be overwatered a bit, that will cause tips to brown.

Greenthumbgrower1986 said:

Hi all. Usually always have issues with my grows with over feeding, currently running 2 auto cheese from fast buds in bio biz light mix. With added perlite. This run I was planning on not feeding untill around week 3 or 4 as I generally get alot of burn so thought Ill give only water and PhD water to 6.4... I've now noticed some browning on the tips of the new growth. How can this be? Surely light mix isn't hot?

Click to expand...

That’s not nute burn. It’s copper deficiency. I get it a lot and have just recently found a fix. Some plants are more susceptible to it than others.

It’s called plant Magic magne cal. A calmag with added trace elements, copper, iron, manganese, zinc etc

Been using it at 0.5ml per L and no more yellow tips.


The difference between nute burn and copper deficiency is that nute burn Will yellow then quickly go crumbly at the tips.

Copper goes yellow with dark/black tips if progresses.

First picture is copper def. Note how yellow it is not brown and crumbly!

Then a plant which has been treated with magne cal since young.

Nutty sKunK said:

That’s not nute burn. It’s copper deficiency. I get it a lot and have just recently found a fix. Some plants are more susceptible to it than others.

It’s called plant Magic magne cal. A calmag with added trace elements, copper, iron, manganese, zinc etc

Been using it at 0.5ml per L and no more yellow tips.


The difference between nute burn and copper deficiency is that nute burn Will yellow then quickly go crumbly at the tips.

Copper goes yellow with dark/black tips if progresses.

First picture is copper def. Note how yellow it is not brown and crumbly!

Then a plant which has been treated with magne cal since young.

View attachment 5361782View attachment 5361783

Click to expand...

Thanks for helping, I'll give it a try

Nutty sKunK said:

That’s not nute burn. It’s copper deficiency. I get it a lot and have just recently found a fix. Some plants are more susceptible to it than others.

It’s called plant Magic magne cal. A calmag with added trace elements, copper, iron, manganese, zinc etc

Been using it at 0.5ml per L and no more yellow tips.


The difference between nute burn and copper deficiency is that nute burn Will yellow then quickly go crumbly at the tips.

Copper goes yellow with dark/black tips if progresses.

First picture is copper def. Note how yellow it is not brown and crumbly!

Then a plant which has been treated with magne cal since young.

View attachment 5361782View attachment 5361783

Click to expand...

Only issue that could arise though is my tap water is very high in calcium already, if I add calmag it would definitely be too much

Nutty sKunK said:

That’s not nute burn. It’s copper deficiency. I get it a lot and have just recently found a fix. Some plants are more susceptible to it than others.

It’s called plant Magic magne cal. A calmag with added trace elements, copper, iron, manganese, zinc etc

Been using it at 0.5ml per L and no more yellow tips.


The difference between nute burn and copper deficiency is that nute burn Will yellow then quickly go crumbly at the tips.

Copper goes yellow with dark/black tips if progresses.

First picture is copper def. Note how yellow it is not brown and crumbly!

Then a plant which has been treated with magne cal since young.

View attachment 5361782View attachment 5361783

Click to expand...

Copper deficiency is quite rare. Usually it’s a ph issue not copper deficiency.

Greenthumbgrower1986 said:

Hi all. Usually always have issues with my grows with over feeding, currently running 2 auto cheese from fast buds in bio biz light mix. With added perlite. This run I was planning on not feeding untill around week 3 or 4 as I generally get alot of burn so thought Ill give only water and PhD water to 6.4... I've now noticed some browning on the tips of the new growth. How can this be? Surely light mix isn't hot?

Click to expand...

If you’re consistently getting these problems with that soil then I would assume the npk valve isn’t the best in the soil. This is exactly why I like to just feed my nutes instead of relying on soil mix. They seem a bit dark green so it may still be too hot for seedlings and young plants.

SofaKingHigh_ said:

If you’re consistently getting these problems with that soil then I would assume the npk valve isn’t the best in the soil. This is exactly why I like to just feed my nutes instead of relying on soil mix. They seem a bit dark green so it may still be too hot for seedlings and young plants.

Click to expand...

Next run I'll try coco

Greenthumbgrower1986 said:

Only issue that could arise though is my tap water is very high in calcium already, if I add calmag it would definitely be too much

Click to expand...

Add Epsom salts to increase mag. Cal - mag ratio should be around 2:1

SofaKingHigh_ said:

Copper deficiency is quite rare. Usually it’s a ph issue not copper deficiency.

Click to expand...

The yellowing tips being pH related or copper not available due to high pH?

Can’t see how pH’d water and light mix will cause pH issues. Biobizz is around pH 6.2

Copper def seems much more common in autos than photos. Ruderalis trait perhaps I don’t know?

I’ve just spent a lot of time researching copper deficiencies and can guarantee that’s what’s up with this plant. As it grows the yellowing will get more pronounced on the new tips of growth with the most drastic yellowing happening in stretch.


It’s most certainly a lack of availability due to no feeds and pH is stable.

If I were the OP I’d give them Epsom salts and that calmag I mentioned to supply a source of copper

Here's some more pics, reason I said nitrogen is because the right plant is curling tips

Greenthumbgrower1986 said:

Here's some more pics, reason I said nitrogen is because the right plant is curling tips

Click to expand...

How are the grow room conditions? Is it dry?

Nutty sKunK said:

How are the grow room conditions? Is it dry?

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55% rh , 24.5°c on a 20/4 schedule. 200w led 30" above canopy

Greenthumbgrower1986 said:

55% rh , 24.5°c on a 20/4 schedule. 200w led 30" above canopy

Click to expand...

Strange to see N tox with light mix with no nutes…

Sulphur deficiency can cause the tips to curl and die off but I doubt it’s that.

High N antagonises copper uptake