Potassium deficiency? Soil grow, White Widow from seed, Sept 2020

[Dadbod]

I think I may have a Potassium Deficiency based on what I’ve read:

SOIL GROW

Strain - White Widow
# of Plants - 3
Grow Type - Soil
Grow Stage - Vegetative (Occurred before transplanting to 3 gallon pot)
Bucket Size - 3 Gallon Geopot
Lights - Mars SP3000 (300W)
Nutrients - Green Planet 1 Kit Medi-one (photo attached)
Medium - 100% Fox Farm Happy Frog
PPM - ?
PH - 6.3
RH - 40% to 70%
Room Temperature -21C to 28C; 71F to 82F
Solution Temperature - 22C or 71F
Room Square Footage - 2ft x 4ft
Pests - None Known
Watering- from Aug 15 to Sept 2 they were watered twice with 100ml each and then once for a full drink on Sept 2 (problem occurred before Sept 2nd). The peat pods and 5x5 containers they were in held moisture really well.

There is such amazing content on this site and I think I’ve been able to decipher what the issue is based on Nutrient Profiles and Deficiencies and the Pest and Problems Chapter of K of Trichomes’ book.

The problem started on Monday when I noticed she had a couple of yellow spots by the edge and then Tuesday morning it spread quite a bit and today it is now on another leaf.

Both leaves that are affected are original leaves, the plant is doing better than its two White Widow sisters, I have added very low doses of nutrients (Ocean Magic and Medi-One) and have being very cautious about watering with today being the first time I fully saturated them all with 6.3PH’d water.

I believe I have a Potassium Deficiency based mainly on the below quote:

Smokin Moose said:
Potassium deficiencies are identified by necrosis on the margins of larger fan leaves. Necrotic patches can be seen on the leaves as well. Leaves will eventually turn yellow, brown and die off. Most of the plants that show signs of a Potassium deficiency are going to be the tallest and best looking plants you have.

My plan of attack is soluble potash:

So here we are; my first lesson in becoming a better grower; every problem is an opportunity for a solution and I am not afraid to do the research, consider a solution and then ask for help

Would love to know if I am right in my diagnosis and solution And if you have ever encountered this and what measures you took to alleviate the issue.

Really appreciate you all contributing, participating and encouraging

 

[Dadbod]

Oops... I didn’t attach a photo of the Nutrients in the first post

 

[OrganiKz]

I have seen this in White Widow and soil PH was too high.
If you have not done so check the ph of your soil or runoff. This very likely could be the problem. A tiny bit off extra nutrients shouldn't be a problem to see if it's a deficiency or not.
Just make sure that soil ph is neutral.

 

[Dadbod]

I have seen this in White Widow and soil PH was too high.
If you have not done so check the ph of your soil or runoff. This very likely could be the problem. A tiny bit off extra nutrients shouldn't be a problem to see if it's a deficiency or not.
Just make sure that soil ph is neutral.

I’ll definitely check that today; I grabbed a soil test kit yesterday.

 

[OrganiKz]

Be very precise with the directions to that kit. It will work if you follow those instructions.

 

[OrganiKz]

I do believe you are going to find your soil ph is hot. That is the cause of the pale. Looks like nutrients are being locked out.

 

[Fuzzy Duck]

That is not K - potassium at best I might pass that off in a plant that size as P - phosphorus which is very unlikely in a plant only a few weeks old !

Oh ye it looks like an indica dominate strain with those little fat leafs

I may suggest light bleaching caused by the led panel you are using it could be a little to close for comfort.

 

[Emeraldo]

A potassium deficiency does look different. Bright yellow areas bordered by crisp dry brown edges would look like a potassium deficiency. Check this out How to fix Cannabis Potassium Deficiency (K) Pics & Symptoms

This summer, several of my plants looked like the photo of K-deficiency there, only it was mainly caused by a heat wave. I strongly suspected K-deficiency because of how it looked, but concluded it was not. Apparently, intense heat (above 100 F, 38 C) can cause a lockout that looks and feels like K-deficiency, even if there is sufficient K in the soil. The leaf markings went away as respects new leaf growth, but the damaged leaves did not recover. Here's a thread I started on this topic. Potassium deficiency? Or heat stress? Or soil pH too high?

A phosphorus deficiency also differs from your leaves (you have lighter splotches). How to fix Cannabis Phosphorus Deficiency (P) Pics & Symptoms

I think your first step would be to check your soil pH to see if it is in the right range before amending your soil. Soil pH fluctuations can also give rise to splotches not unlike yours. Cannabis pH Management - How to adjust pH in Water and Soil But contrary to conventional grow wisdom, you needn't pH your water -- if soil pH is in the right range, you're good.

Good luck and please post your further findings, like soil pH.

 

[Dadbod]

That is not K - potassium at best I might pass that off in a plant that size as P - phosphorus which is very unlikely in a plant only a few weeks old !

Oh ye it looks like an indica dominate strain with those little fat leafs

I may suggest light bleaching caused by the led panel you are using it could be a little to close for comfort.

This could make perfect sense; I did stretch the light one day so that I could shift the scheduled day/night rhythm and this was prior to the problem showing up...

 

[Dadbod]

A potassium deficiency does look different. Bright yellow areas bordered by crisp dry brown edges would look like a potassium deficiency. Check this out How to fix Cannabis Potassium Deficiency (K) Pics & Symptoms

This summer, several of my plants looked like the photo of K-deficiency there, only it was mainly caused by a heat wave. I strongly suspected K-deficiency because of how it looked, but concluded it was not. Apparently, intense heat (above 100 F, 38 C) can cause a lockout that looks and feels like K-deficiency, even if there is sufficient K in the soil. The leaf markings went away as respects new leaf growth, but the damaged leaves did not recover. Here's a thread I started on this topic. Potassium deficiency? Or heat stress? Or soil pH too high?

A phosphorus deficiency also differs from your leaves (you have lighter splotches). How to fix Cannabis Phosphorus Deficiency (P) Pics & Symptoms

I think your first step would be to check your soil pH to see if it is in the right range before amending your soil. Soil pH fluctuations can also give rise to splotches not unlike yours. Cannabis pH Management - How to adjust pH in Water and Soil But contrary to conventional grow wisdom, you needn't pH your water -- if soil pH is in the right range, you're good.

Good luck and please post your further findings, like soil pH.

This is amazing @Emeraldo ! I’ll definitely be posting the soil results when I get the chance!

 

[Rad Man]

Looking at your data, you state you are in a soil grow. (Happy Frog)
Yet the nutrient feed data sheet you pictured is for a soil-less/hydro/coco style grow. This will result in you missing your pH target.
I think your pH is too low, locking out P. Your target feed pH should be 6.5 according to this chart.

According to the soil chart on the right, you are feeding yourself into a P def.
The soil runoff kit will show your soil has adequate P available, (it is in the soil) but the plant can't uptake the nutrient if your pH is off.
At this point, remember the scarred leaves will probably not heal, when you get this corrected. The point is to stop the negative trend.
I think adjusting your feed pH may just get you out of this.

 

[Rad Man]

My first glance reaction was light/heat stress, check your light positioning. Those LED lights can scorch some tender leaves, but this usually happens at the top of the plant. Check heat controls while you're working the problem.

 

[GreenGrowth]

I've had similar problem, was the light (led) distance from the plant, lifted further than recommended height and haven't looked back.

 

[Emeraldo]

... I think adjusting your feed pH may just get you out of this.

Hey Dadbod

Rad Man has some good points there.

I would only add that adjusting your feed/water pH probably won't help. I used to pH my water every irrigation and it was a lot of work. This summer I had input from a number of growers here on 420 (see my earlier thread on Potassium Deficiency?) where I realized I had to go back to school!

InTheShed has a really eye-opener of a thread here: Do we need to pH adjust our nutrient solutions?

 

[Rad Man]

The alkalinity of your water can have a large influence on your need to pH. I believe that's why we have seen so many different results between the pH and non-pH crowds. God bless the folks who don't have to pH their feeds.
I, on the other hand, avoided major catastrophe by adjusting my feed pH in a indoor HP-Promix grow.
Just curious @Emeraldo , you were in an outdoor soil grow? (Your use of the word "irrigation" made me wonder)

 

[Emeraldo]

Yes, Radman, all my grows are outdoor, I've never grown indoors. I am from a farming family, and watering is often referred to as irrigation, lol. In my current balcony grow, I set it up using garden irrigation tubing so I really do "irrigate".

Please review InTheShed's thread, which is excellent. It's the alkalinity of the soil that is controlling (akalinity of water isn't something I've heard of). Soil alkalinity is said to the capacity of the soil to maintain a stable soil pH without going lower. Without sufficient lime, for example, soil tends to go lower in pH.

 

[SoGnotSOG321]

Did you get the leaves wet while your lights were on and then leave them? Looking at the location, to me it looks like water stuck or sat on the leaves as it drip dried. Of course the ph issue and solutions offered might blow my idea out of the water, good luck

 

[Dadbod]

Soil Test Photo Update; Sept 3, 2020

Took 5 tablespoons of soil and set one aside for the PH Test and the other four were mixed with 20 tablespoons of water and vigorously shook:

first was the Soil PH Test:

I’d say it came out around 6.5

next is the phosphorous which I would say deficient :

Nitrogen is in surplus:

And finally Potash which appears to be depleted:

I’ve only just finished doing the test and look forward to reading the amazing threads that were linked earlier to find
solutions...

Love the contributions, assistance and “forum mentoring!”

 

[SoGnotSOG321]

Determination and dedication. It pays. Lots of nice grows here that show how along with those, patience is paramount.

 

[OrganiKz]

The alkalinity of your water can have a large influence on your need to pH. I believe that's why we have seen so many different results between the pH and non-pH crowds. God bless the folks who don't have to pH their feeds.
I, on the other hand, avoided major catastrophe by adjusting my feed pH in a indoor HP-Promix grow.
Just curious @Emeraldo , you were in an outdoor soil grow? (Your use of the word "irrigation" made me wonder)

How can you not ph your feed. Its instant problems if you give them some hot feed. You gotta know your waters ph and what it is when your feed is mixed in.
You will have twisting, looking like light burn, or a diffeciancy on your new growth. I have had hot feed almost take a couple plants 2 weeks into 12/12 from me. Luckily I tested the soil and was able to flush with neural water quickly to save them.
Ph is very important in my book