Want advice on whether to flush or not and: assume nuteburn

Hi take a look pls

Plants are 41 days since sprouting out of soil and 27 days since flipped 12/12.

They are in a premade synthetically prefertilized soil with compost, sand & perlite mix. It's starting ph is 5.9

Pots are 0.8gallon

I give rainwater only. Did once foliar sprayed groundwater high in humus but i stopped due to these problems.

I guess that the soil is too hot and it burns the tips (mostly top of the plants but also seen on lower growth)

There are also some parts of the leaves "missing"

Complete with some clawing much like in nitrogen toxicity afaik


Imho it's nutrient burn and it started going into the 3rd week of flower so pics are about a week of progression.

Q:

1. if you can pin the diagnosis
2. if it is nutrient burn; whether i should flush; and when if should flush?
3. How bad is this?

Fwiw i wasn't planning on flushing lest necessary because i wanted to watercure whole plants.

I am unsure what strain it is but they look indica dominant to me. They barely started getting frosty and seem to have stopped stretching. I assume harvest in 4-5 weeks if they don't die on me.

Thanks in advance

Don’t flush for nitrogen problems this slight. Keep going.

Just back off the nitrogen for a bit. It will correct itself.

Wizzlebiz said:

Just back off the nitrogen for a bit. It will correct itself.

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It’s prefertilized. But nitrogen is the most quickly depleted nutrient.

hotrodharley said:

It’s prefertilized. But nitrogen is the most quickly depleted nutrient.

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Raise the PH.

MICHI-CAN said:

Raise the PH.

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I was considering using wood ash

Icu420 said:

I was considering using wood ash

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PH up. I use bio char. Hardwood charcoal in my soil mix. As a trace element and mineral source. Not buffering. Too slow and erratic for that.

MICHI-CAN said:

PH up. I use bio char. Hardwood charcoal in my soil mix. As a trace element and mineral source. Not buffering. Too slow and erratic for that.

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As i understand it, wood ash is ph up. I top dressed some and added ash to the water in order to increase it's ph as well.

Icu420 said:

As i understand it, wood ash is ph up. I top dressed some and added ash to the water in order to increase it's ph as well.

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It is. But it has no buffers or stabilizers. And how are you computing and measuring the actual effect? I appreciate your intent on natural. But not needed. I would just raise my water PH and watch it solve it's own issues. LOL.

MICHI-CAN said:

It is. But it has no buffers or stabilizers. And how are you computing and measuring the actual effect? I appreciate your intent on natural. But not needed. I would just raise my water PH and watch it solve it's own issues. LOL.

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I think i got too trigger happy and careless. Ash is what i had at hand and there are no means of getting anything else for 5 days. I figured that the soil was kind of low to begin with @5.9, googled that rain water is 5-5.5, so i figured the soil must be getting well acidified by now.

Furthermore figured that i would take the chance and didn't want to pester you more with this.

I assumed it would be better than doing nothing and planned to water them with ph adjusted water thinking that it probably wouldn't increase the ph too much inb4 i get the ph measuring tool.

So raising the PH will reduce the nitrogen uptake? I think I'm too heavy in Nitrogen also, but I'm only using a 1 bottle "bloom" fert. Reducing nitrogen would require me to reduce the amount of the entire feeding.

Soul Dwella said:

So raising the PH will reduce the nitrogen uptake? I think I'm too heavy in Nitrogen also, but I'm only using a 1 bottle "bloom" fert. Reducing nitrogen would require me to reduce the amount of the entire feeding.

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Has to be quite alkaline to inhibit nitrogen uptake as i understand it whilst phosphorous uptake is quickly inhibited by even slight acidity. I think in my case the goal is to prevent phosphorous deficiency and especially now 4 weeks into bloom.

It's kind of depressing, i guess these buds will be tiny because ph is too low and buds have been forming for 2 weeks.

Wood ashes are very alkaline at 9-11 so i will try not to overdo it if i didn't already... probably did overdo as i sprinkled like 4-5 table spoons and watered on top.

I guess with this amount top dressed i better not increase water ph.