Nitrogen Toxicity or Deficiency?

Hi All,

I have been on these forums for years but just started up growing again after some time.

Basically, the top of my plants look like Nitrogen toxicity- dark green and slight clawing but the bottom looks like a deficiency- yellow leaves that eventually die and fall of.

I am using minium nutrients as worried about over fertilising (did a bit at the start) and have vitalink calmag but not used it as do not want to cause further damage (not really sure how to use) Any suggestions would be appreciated.

Thanks.

Grow Room - Approx M2 Tent
Light - 400w HPS
Airflow - Active intake and exhauste
Strain - Big Bang GHS
Medium - Biobizz All Mix soil in 11 lt pots
Nutrients - Biobizz Grow at 1ml per liter @ Biobizz bloom @ 1ml per liter every watering (about every 3 days)
Stage- 4th week of Flowering (after vegging for 5 weeks)
Temps lights on- 23 at bottom of tent to 26 at cannopy.
PH - Water in / run off around 6 (only have the paper strips)

Overwatered but not overfed. Looks it was actually short some nitrogen.

They are not over watered for sure - only watered when the leaves droop instead of on a schedual. This pic was taken right after watering.

Thanks though.

Commotus said:

They are not over watered for sure - only watered when the leaves droop instead of on a schedual. This pic was taken right after watering.

Thanks though.

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So what is the problem? What do you do to remedy this?

hotrodharley said:

So what is the problem? What do you do to remedy this?

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Fair enough. Just wondering why all the leaves are turning yellow/ dying at the bottom. Like you said,it is probably a Nitrogen deficiency.

I was wondering if the top was Nitrogen toxicity as the leaves there seem to claw. On these forums I have seen a few posts saying that Cal/Mag deficiencies can present as a Nitrogen problem, so was looking for opinions and if Cal/Mag supplementation would be worth while, in this instance.

Cheers

I don’t see nitrogen toxicity or calcium deficiency in your pictures. Just give a tiny nitrogen boost and watch for new fading.

hotrodharley said:

I don’t see nitrogen toxicity or calcium deficiency in your pictures. Just give a tiny nitrogen boost and watch for new fading.

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Awesome. Thanks for your input. I think I was looking too much into this but glad I never added cal/mag. I will just up their nutrients.

I wouldn’t leave dead leaves there, invitation for bugs. Nitrogen is mobile, the plant is taking from the bottom to feed the top. Try a light foliar feed of your veg nute.

Kerowacked said:

I wouldn’t leave dead leaves there, invitation for bugs. Nitrogen is mobile, the plant is taking from the bottom to feed the top. Try a light foliar feed of your veg nute.

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Nice one. Will give foliar feeding a go.

Kerowacked said:

I wouldn’t leave dead leaves there, invitation for bugs. Nitrogen is mobile, the plant is taking from the bottom to feed the top. Try a light foliar feed of your veg nute.

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Oooh, can you tell me more about this? What strength or TDS do you use for foliar feeding veg nutes?

jfarrismu said:

Oooh, can you tell me more about this? What strength or TDS do you use for foliar feeding veg nutes?

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1/2 of whats on the bottle, Grow Big 1/2 splash per gallon. Its pretty simple really, the top needs nitrogen and the quickest delivery is foliar. It won’t bring back yellow leaves but definitely slows or stops the progression.

You should have bumped your nutrients up to full strength when you flipped it to flower. Plants eat the most during flower, especially during the first half. Follow the feed schedule provided by the manufacturer, it exists for a reason.