Nutrient deficiencies and toxicities in Cannabis

[uBercaMeL]

@popitin

Hi, bit late replying but they are showing nutrient toxicity, either from too much accumulating over time (too strong feed, bad watering practises, or both) or PH out of range. Your feed levels are very high, and looking at earlier pics I'd go with them just being fed too much through early flower, and introducing too much PK too early..

How often do you water/feed and what size pots are they in?

If you have an ec meter, what are they on? I'd have them on 1.4 ish at that stage, no PK until week 5/6 and at much lower amounts (you arguably want to tweak the a&b levels towards slightly higher PK:N, not double the PK). Your current PK amount is adding as much or more P and K as are in the a&b on top, completely unnecessary and usually leads to lockouts ime. I just did one of my better grows to date and under a 600w, feeding 3x a day I hit 1.6 ec total, with .2 of that coming from added pk (0.25ml/l of 14-15, then 0.2ml/l of 18-23), and .5 being tap water base. And a max of 2.5ml/l a&b (5-3-5).

What ec is the run off ? (make sure tray is dry and clean, and give a good feed with decent run off and measure).

Especially if run off ec is very high, which I'll bet it is, I would drop ec to 1.2ish for a few days, up watering frequency (assuming they are well rooted out which they should be), and stop giving them PK for at least a week.

 

[popitin]

@uBercaMeL
Thanks for the reply none the less. You can probably still help.

Just coming to the end of week six in flower, white widow photos.

 

To much pk was the problem.

BUT I thought first of: not enough Phosphorus, so I upped the pk and cut the calmag. Very bad idea as you are probably laughing now reading this.

Also the light was far to close. like 8 inches closer than it should have been.

 

So once I realized this, like the next day, I flushed her with 25 liters of water and went back to 2/3 a&b, 1/4 pk, and upped the calmag by 2ml.

Now feeding at, honestly I don't know the EC, I brought a cheap ppm pen off ebay but I do not know what it reads in, I know there are three different charts but the ppm is around 1100 now according to the pen, so that could be EC 2.2 or 1.6 or 1.8???

5liters every day 10-20% run off, more closer to 20

 

The run off? I just checked was 3560 but that's including yesterdays, I have not emptied it yet. Again it depends on the pens reading but I know that's pretty high, also the salt build up in the tray the run off collects in...

 

 

Still gone better than I expected for a first grow.

[pepe16]

On 6/27/2019 at 0:42 AM, Poisonata said:

 

Novice grower. Researched growing for months prior to starting. These few sentences are probably the most useful thing I've ever read. In my short time as a grower I have to concur never a truer statement was made. The only problems I've encountered are either of my own making (watering) or environmental factors. On so many sites focus on nutrients / pH was given far more importance than the basics, to the point over diagnosis and potential harm giving supplements not required. But this confirms it, much information is outdated / no longer relevant. My wholehearted thanks for this   

You've got it dialled in now mate.  I've been sent back to 2nd year secondary school    

 

[Lunaloo]

Can anybody help me please? 
first time grower, this is my first plant and everything was going great up untill now. My

leafs seem to be going brown at the ends and going crispy. I thought it was just because they where old leaves but now it’s started to work it’s way up the plant. Also noticed that the leaves that are going like this have purple stems. Sorry if this sounds stupid but I am completely new and I’ve tried to research and watch YouTube videos but I can’t seem to get my head around why in the last 3 days my leaves have gone like this. 
 

any help would be appreciated. 
thank you 

(I will post a photo when I work out how ) 

[Shumroom]

@Lunaloo

 

Atb 

 

And welcome to UK420 

 

 

 

[Whatwentwrong]

You'll need to post photos or we'll have no chance mate. 

 

There are a few things that can cause brown tips but the two common ones are over doing the bloom nutes and giving it nutrient burn, this shows at the very tip first and then progressively gets worser going down the leaf. 

 

The other is light damage, that will have leaves shaped like canoes, the very end tip plus all the tips on the serrations along the leaf will all start going brown and crispy. This starts at the top though and goes down the plant. Nutrient burn can start lower down but without photos we don't know. 

 

Also, what strain, how old are the plants are they flowering at the minute, what lights are you using, what brand nutrients and how much. Also do you know what temp and rh your grow area is. 

 

It's getting hot as hell in mine at times. I've had to drop the light down the 66% power to maintain 28 degrees in the tent even with the extraction going mental. 

[High007]

the lowermost leaves of my mother plant, which seems to have gone into flower, are developing these small brown necrotic patches between leaf veins, looks a bit like rust, is this a phosphorous deficiency?

[Whatwentwrong]

Could be calcium def too. How old is the mum and are you adding calmag in your feed. 

 

Posting photos is the only way we can see. 

[High007]

On 6/12/2021 at 8:58 PM, Whatwentwrong said:

Could be calcium def too. How old is the mum and are you adding calmag in your feed. 

 

Posting photos is the only way we can see. 

 

I cannot get calmag here, otherwise i would, i did get and use epsom salts, but i realize that doesn't have calcium in it, I've been checking out youtube for natural fast release sources, so far overwhelmingly is the eggshell and vinegar method (1:1 ratio) and let it sit until it stops foaming, about 30 minutes they are saying, but... another video says to let it sit for a week or two, is he full of crap or what? then mix it with a gallon of water and the calcium is readily available for plants, is this true?? also they keep saying that the reaction with the eggshells neutralizes the vinegar so it won't affect pH, is this also true?? so much info out there, i haven't been in this game long enough to see the patterns yet. As for photos, i took som but then my stupid phone decided to stop working (screen is screwed up) maybe i can pull the pics off with my pc, i'll try that soon, but otherwise it will have to wait until i fix it.

[Thai Stick]

Only just noticed this thread pinned at the top.
Think it would be much better for me to post my pictures up here to help others as apposed to my own thread (which i already started a few weeks back) which probably will get lost along with any valuable information that may be shared.

 

So before i go chasing my foxtails again....
Does she look hungry?
Or does she look overfed causing a lockout?
 

Environment 25'c-28'c Humidity 65%-75%
Lighting 240w lm301h 3500k + CREE XP-G3 660nm turned down to 220w
7gal Compost that's approximately 20% rice husks 20% coco 60% organic matter such as worm castings, bat guano, bone meal....lots of stuff in there.

Fed a combination of blue-green algae and brown seaweed extract @ 1ml/Ltr & 2ml/Ltr Liquid Bat Guano and a topdress of a humic acid and bonemeal mix.
 

Anybody got their 2 pence worth of advice?

 

[Thai Stick]

For those interested in what the problem was.
It was a case of overwatering.

 

Let her dry out a day more between waterings and gave a little less water and she bounced back.

Did add an extra week or two onto the final grow time though.

[Hungryfloppy]

Hey people so had some real problems with a cheap EC pen which was reading way over than it should have been, bought a bluelab trucheon today which read 0.2 ec for my tap water but my first pen read 0.7 1 week then 08. and 1.0 finally today. So got exodus cheese seedlings at 2 weeks old that only have 0.1 of A n B canna added to make 0.9 for the first feed assuming my tap was 0.8 when I fed those babies, last few days they been wilting and today they looked worse since fed days ago but I discovered the problem today with new decent ec pen. Instantly fed them 1.0 EC A n B and they still look shit but wondering can they come back from lack of nutrients with more or less plain tap water? I know underwatered plants can bounce back but is this the same? If not I can order more right now rather than waiting Ive made many noob mistakes so far and cost myself weeks but this one is from bad cheap equipment and could do with knowing the possibilities. Thanks grow is in coco

[Hungryfloppy]

Ive also got 9 autos a few days old that the coco was soaked in plain 0.2 ec water that I thought was 0.9 ec, do I wait till they dry a bit or feed them again with some nutes before they wilt?

[mysticriver]

the chart at the start of this post - it hasn't one of the most common issues - Calcium

jus sayin'

 

 

mystic

[Bong-Zilla]

Easy now,

 

I’ve just noticed these small brown spots, - any ideas what it might be? I’m pretty sure it’s a calcium deficiency but interested to see what you experts think? Nice one

 

Edited April 27, 2022 by Bong-Zilla