Yellowing with brown, necrotic spots : BioTabs - Coco - AutoPot

[Neoliet]

GREEN CRACK PUNCH (ROYAL QUEEN SEEDS) FEMINIZED

AutoPot 25l with airdrome - Coco 50% Perlite 50% mix with BioTabs starters pack - clay pebbles bottom of pot

Spider Farmer SF2000 - 100% intensity - Led to plant distance 80cm


Daytime temperature 22° Celsius

Nighttime temperature 18° Celsius

Humidity ~60

—————————————

NUTRITION :

Week 3 - 4

3 BioTabs in Coco mix

Watering: 2ml / L Orgatrex (BioTabs) with bottled spring water

1 x 500 ml PK Booster Compost Tea (BioTabs)

1 x Seed Sprout Tea (Barley, Alfalfa, Corn, Lentils)

10 x BoomBoom Foliar Spray (BioTabs) 0,5 ml / 100 ml

——————————-

This is my first grow:

Week 3 :

I transplanted the seedlings from start pot : 50 % soil - 50 % perlite in week 3 to AutoPot.

Week 4 :

I hanged the led 10 cm higher and slowly intensify the light from 60% to 100 % power.




Problem :

Week 2-3
Lower fan leaves starting yellowing, top fan leaves starting curling up on the edges a little bit.


Week 3
After transfer, faster and healthy growth. The ladies were topped 2 days ago, after the 3 node when they had 6 nodes.

We are now in week 5 and I did a watering (PH 5,8), runoff with PH 6,8. Then I applied the Foliar Spray and took the photo.




I’m hoping that someone can tell me what is causing the brown patches /spots on both plants.

 

[JohnEmad]

Hey Neoliet welcome to GWE forum. Seems you have done your homework and have most everything needed for a good grow. Honestly I cannot see any brown spots on the leaves and things look healthy.
One of the main reasons leaves yellow in coco is due to a greater need for cal/mag. Even if the manufacturer says its pre buffered. I have found xtra cal/mag is usually needed. Especially during the 1st month.
Great start to your 1st grow. Congrats

 

[Neoliet]

Thank you JohnEmad, I already had ordered CalMag from BioBizz, I will give some with my next watering. Let’s hope that will help!

Maybe you can see the brown spots in this photo? The photo was taken 15 min later with 100 % light intensity.

 

[JohnEmad]

It could be a calcium deficiency or perhaps heat stress. Have a look and see what you think.

https://www.growweedeasy.com/cannabis-symptoms-pictures

 

[homegrown]

Agree with JohnEmad on both his suggestions. The leaf spotting appears to be cal-mag deficiency. But, i would also turn your lights down and lower them. Full power is never a good idea for a seedling(good chance of burning them) and lights too high is just going to cause stretching and a weak stem. You have to ease them into full power lights.

 

[Neoliet]

Thank you homegrown, yes you are right l! I had some trouble with the intensity and hanging height.. I followed the directions of Spider Farmer.

No stretching and small internodes. But some curling up leaves (only on the edges). I want to do soon LTS for manifold. That’s the reason I hanged the LED higher, to get some longer internodes.

 

[dilvish]

at those room temps, if the leaves are curling up it's likely the light that's causing it. the spotting could very well be cal/mag deficiency. Cal/mag should always be used with coir IMHO

 

[Neoliet]

dilvish Thank you !

I did some research and I found out that DLI range in veg stage needs to be 25 - 45.

My grow tent is 120x60 cm and I have found for my led and grow tent dimension a PAR-map. The test is with 100% light intensity.

With an average PPFD : 572,6 umol/s/m2
With 18 hours lights on is the DLI = 37.10

Why are my plants suffering with lower light intensity and higher height? That is because the plants footprint is still very small. I dont have a Sea of Green or full canopy, all the photons are bouncing up and down till they get absorbed by the few fan leaves. Overkill !

But when I flip I can’t get enough DLI in 12 hours…
That really sucks ! Any suggestions for this run?

 

[Neoliet]

homegrown I think it’s better to hang the led higher because the PAR is then more equally spread over the surface , from the center to the edges. Also you will have lesser risk on burning the leaves.

I will add the Cal/Mag and for now (veg stage) I will follow this: hanging height 76.2 cm with full blast 💥

Actually I need more juice and I will ask Santa 🧑‍🎄 for an additional SF1000 to get the ladies through end veg stage and into flowering !

 

[dilvish]

Something doesn't seem right with those light distances. I have a Viparspectra full spectrum R900W (450Watts from the wall) and even it states the maximum distance is 24 inches. I have never had it closer than 18 inches and my plants do fine so i am uncertain as to why this light you have requires a distance of 30 inches when it only draws 200 watts from the wall...mind you it is referring to a tomato plant in the images.

having said this they don't appear to have light burn from the last image. "cupping" is usually caused by heat or light but you said the temp was 22C so I am curious as to what you mean...maybe post a pic of the whole plant..

 

[Neoliet]

JohnEmad I think the damage was done in week 2 -3 but is really showing now in week 5. I did not had my filter and fan running, heat stress or light stress (going to fast up with light intensity). Also from week 4 cold air is coming in. New growth had not any problems with full intensity. But it looks they are cannibalising the old leaves down under for accelerating growth to compensate deficiency caused by PH or no Cal/mag available cause the coco has it all or the infrared leds trigger an eager for it!

 

[Neoliet]

dilvish I will back home soon.. actually the picture I was referring to is not a tomato 🍅 but medical “tomato”. Only the par test is done in 90 x 60 cm something …

https://youtu.be/lK28aiRQ_Vs


PAR - test 2x4 with different distances SF2000
https://youtu.be/B02ew20nH7w

PAR - test 2x4 with different distances SF2000 + SF1000
https://youtu.be/-bcorCRHFG8

The spy camera is showing new growth after topping I will count the nodes tomorrow and make some good pictures..

 

[Neoliet]

Those hippies geeks from YouTube did the PAR-test in a empty grow tent with reflecting floor and Sealing. 🤔

 

[JohnEmad]

Sounds like you are figuring it out. That's what growing your own is all about. Trial and error until you get it right.
I find that gives me a good deal of satisfaction. Greast thing is there are many people here to help speed up the learning process and the encyclopedia of info on the GWE site.

 

[Neoliet]

JohnEmad ..

Top watering for each plant:
3 liters bottled spring water
1 ml / L Cal/Mag (Biobizz)
3 ml / L Orgatrex (BioTabs)

PH = 5,5
Water runoff = PH 7,8

4 days after topping (week 5) before watering:

Plant 1:

Plant 2:

Led to plant height lowered to 76 cm

 

[Neoliet]

dilvish the damage has progressed

After watering and
BoomBoom Foliar Spray (BioTabs) 0,5 ml / 100 ml

 

[Neoliet]

What is that black stuff ??

 

[Rwise]

First you have a PH problem, it is causing those spots as the plant eats the nutes from the leaves that it cannot get from the media.
The black looks to be botrytis (bud rot), what is the RH?
Also foliar feeding can burn the plants causing spots where beads of moisture were with the lights on. When spraying the plants keep the lights off until they are dry. Excess moisture on the plants can also cause bud rot (botrytis).

 

[Neoliet]

Rwise thank you! I don’t know why the runoff has this high PH.

4 days ago, I set the minium temperature of my tube heater on 22° Celsius to stimulate bacterial life. But now I have another problem, fungi are eating my affected leaves and stem !

The RA is around 60 (with the exception after watering and spraying) ,and go down to a min of 40 before watering again (3 days).

I have a problem with the autopots, contacted the manufacturer today, they are sending me a new system for free.

I can give more power to my exhaust filter so the RA will drop more.

lights out are at 13:00

 

[dilvish]

do you know what the biotabs are made up of? I went to their site and couldn't find anything regarding the NPK or Cal/Mag percentages. That in of itself could be the problem. without knowing exactly what you are feeding is a real issue

PH going in at 5.5 is too low I'd aim for 6.0 in coir