Diagnosis For Yellowing & Brown Spots & Maybe Slow Flowering

[MidgeSmith 1,671]

Can you help me with a bit of diagnosis please?

I know I have introduced a lot of variables.  It looks like a potassium deficiency to me but I am inexperienced and not certain. I am probably trying to do too much at once considering I have less than 10 grows under my belt, but hey, that's where I am at.  If you can tell by the images what is likely to be wrong I would appreciate the help.  I am watering / feeding again tomorrow and planning to give them a watering with the usual feed and supplemented with 1tbsp/Litre of bat guano tea to try to add some P & K in case that helps. I could alternately just increase the Biobizz Grow - which I am currently using at about 1/3rd strength to complement the supersoil / allmix in which the plants are growing.

 

PLANTS

1 Chocolate Mint OG Auto with paler leaves than I am comfortable with, with more yellowing between lateral veins, quite stretched (very sparse seeming buds for 4 weeks).

1 Chocolate Mint OG Auto that is squat and forming reasonably chunky buds with some leaf tip yellowing and browning.

1 Sour Diesel Auto with pale leaves yellow tips and fringes and brown spots.

WHERE WE ARE AT

4 weeks into flowering (after 4 weeks vegging)

LIGHTING
20/4 Schedule (as recommended by HSO who produced the Chocolate Mint OG Auto Seeds) Kingbrite 320W 3000K dimmed 65% at 60cm from Canopy

2/22 UVA 60W at 60cm (1 hour start of day, 1 hour @4 hours before lights off)

1/23 Far red 60W (last hour of illumination)

ENVIRONMENT

26C Air / 25C Leaf / 50% RH Air 

 

SUBSTRATE

2/3 Biobizz All-Mix mainly at the top of the pot : 1/3 Ecothrive with Charge mainly at the bottom of the Air Pots

 

WATER / FEEDING

Alternate days (when dried to top 3 cm soil)

Water PH before additions ~7.5pH after additions ~6.5pH

Total per plant: 1.75L Water with 1ml Biobizz Grow (Molasses & N),  1ml Biobizz Bloom (PK), 1ml CalMag (soft-water area - seems to help)

 

Any clues would be appreciated.

 

 

Edited March 23, 2022 by Cursed
External link removed.

[mysticriver 2,893]

16 minutes ago, MidgeSmith said:

help me with a bit of diagnosis

im no expert but that leans towards a Mg issue for me. with maybe a little Ca thrown in but not much.

18 minutes ago, MidgeSmith said:

after additions ~6.5pH

are you sure this is not creeping up further? but I dont think thats an issue

20 minutes ago, MidgeSmith said:

WATER /

getting plenty of run-off? again not an issue here but it helps...

to summerise: Mg

 

 

mystic

[mysticriver 2,893]

22 minutes ago, MidgeSmith said:

It looks like a potassium deficiency to me

it could well be that bro take what I say with salt

 

 

mystic

[MidgeSmith 1,671]

Hi @mysticriver,

It's easy enough for me to up the CalMag to 3ml/Litre is if it Magnesium / Calcium.  Our water is pretty soft.  I did a one off 3ml/l a few days ago (EC 0.4 which is the level BioBizz recommend you take it to for correction before adding nutrients) which didn't cause any further problem, most waterings I have it at 1ml/Litre out of caution really.

 

I am never 100% sure with the pH as my meter is a £10 cheapy job, but seems to be between 6 - 6.5 after mixing all the nutrients in and being in soil, essentially felt I was safe.

I water to run off each time, but haven't been pushing it through beyond seeing that there is runoff.  I water slowly, giving a little to each first to dampen the surface so it doesnt run down the sides without wetting the core and then giving each one 1/3 of its feed in turn before giving the next third and so on.  I can water until it runs off far more if that would help.  I don't have a good way to remove the runoff though, so have been using a turkey baster to suck it up.  Being in air pots, the soil is kept well above the run-off though, so I know it isn't sitting in fluid.

Thanks for your suggestions dude!

[Shumroom 23,472]

Do you have a diary on the go? 

 

 

They look hungry. 

 

How's the root temperature? 

 

Atb 

 

 

[Tegridy Farms 2,314]

1ml of biobizz calmag is 0.1ec

 

you need to get your water to 0.4 then add the rest.

 

do you know the ratio of your ca to mg in your water? It wants to be 3:1.

 

also are you adding 1ml of grow & bloom to 1.75l of water? I’d have thought that should be per litre of water mate.

[MidgeSmith 1,671]

3 hours ago, Tegridy Farms said:

1ml of biobizz calmag is 0.1ec

 

you need to get your water to 0.4 then add the rest.

 

do you know the ratio of your ca to mg in your water? It wants to be 3:1.

 

also are you adding 1ml of grow & bloom to 1.75l of water? I’d have thought that should be per litre of water mate.

Yeah, it got lost in the editing.  For correction (last watering) I had the EC to 0.4 - thought I had written that -too many redrafts

I have no idea of the ratio of calcium to magnesium in the water, it doesn't seem to be displayed anywhere.

I am adding 1ml/Litre of both grow and bloom - I can't edit the OP now, thought I had written that, thanks.  I went up to 3ml / Litre of bloom for one feed to try to get them better fed.

@Shumroom I haven't a diary online no, I log everything I do or think. I agree they look hungry, the leaves are not green enough for me to feel I am succeeding either.

So, so far, the feeling is that if I boost the CalMag, it may well sort any lockout.  So would you say that I shouldn't bother with the guano just yet, but keep giving corrective levels of CalMag until it appears to be sorting itself out?  Only boosting the PK significantly once I know if the CalMag is a problem?

I know that the water where I live is very soft, so it would appear to be a prime suspect.  How many days with corrective levels of CalMag would you expect to see the leaves becoming more green again on average?

I think this problem is retarding the potential and growth significantly, so I will be doing everything I can to sort it out.  I just don't want to rush at it like a bull in a china shop and try several things at once.  So for now, I am going to try 2 or 3 consecutive feeds with a full recommended dose of CalMag and see what happens.  That'll be 4 - 6 days.  If they are going to respond, they should show signs in that kind of time-frame right?

Here's all I could find about our local water supply:

 

So it seems to show the Calcium levels above?  Do you think CalMag is the best bet or should I be adding Epsom salts to the water instead?  I have no idea of how much to use if that is the case, but I can research it if there could be a problem adding CalMag instead.
 

Cheers for the guidance as ever fellas!

Edited March 23, 2022 by MidgeSmith

[Shumroom 23,472]

@Oldbear can you please advise on Ca Mg levels?

 

Atb 

 

 

[MidgeSmith 1,671]

Just to recap In the water supply, there are calcium levels as CaCO3 as above 23-40mg/L.

Currently routinely adding 1ml/L Biobizz CalMag as a maintenance dose.

Biobizz say 0.4EC in water before nutes is a solid corrective dose, which I have used once, 5 days ago.  3ml/Litre gives me the 0.4EC recommended by Biobizz.

Edited March 23, 2022 by MidgeSmith

[Tegridy Farms 2,314]

The damaged leaves may not revert back to looking green and healthy, what you are looking for is that it is no longer spreading across the plant.

 

Your water report doesn’t show how much mg is in your water, perhaps you could contact them and ask?

[MidgeSmith 1,671]

I was hoping that they might green up a little at the same time, but yeah, I do a lot of wishful thinking

I can ask re: Magnesium.  I asked before and got no reply, it couldn't hurt to try again. Since Cannabis seems to like a lot of Calcium, I feel like I won't do any harm running a few feeds with the corrective dose of CalMag in it while I wait.

Edited March 24, 2022 by MidgeSmith

[Oldbear 9,729]

6 hours ago, Shumroom said:

@Oldbear can you please advise on Ca Mg levels?

 

Atb 

 

 

No magnesium info on that table, the calcium is fairly low so soft water but you could do with knowing. I'd be cautious adding calmag blindly you could compound the issue. Try contacting your supplier or get @One Tree Horticulture to test your water.

 

[Shumroom 23,472]

Thanks for your response @Oldbear

 

@MidgeSmith it does look like a good idea to get your water supply tested, 

to be sure what you're starting point is with regards to the Magnesium content and therefore it's ratio with Calcium. 

 

They should ideally be around 3:1, Ca:Mg

 

Atb 

 

 

[MidgeSmith 1,671]

Thanks guys, that is very helpful!

[mysticriver 2,893]

22 hours ago, MidgeSmith said:

I don't have a good way to remove the runoff though,

ive started using a large syringe (250ml)

11 hours ago, MidgeSmith said:

Since Cannabis seems to like a lot of Calcium

too right there - im now adding the maximum, 2ml/L, of calmag to my mix. id already upped it to about 1.5ml/L - that equated to 0.5ec - however the tests im currently running found my seedling(s) were left wanting in the Ca department even at 1.5ml/L/0.5ec... so now ive put the ec pen down and upped the calmag to 2ml/L, then coco nutes.

I do think thats got it (2ml/L calmag; 1.5ml/L coco a&b, for seedling stage)

and I hope you get your issue sorted

 

 

mystic

Edited March 24, 2022 by mysticriver