Mid flowering - K def?

[Delty]

-Problem: Gradual yellowing of upper leaves and tips of sugar leaves. Some rust spots
-Medium/grow method: Canna Pro Plus Coco in 5 litre airpot
-Feed and supplements used: Canna Coco nutrient line according to Canna Light Feeding chart, though scaled down slightly. Currently 1.0 EC of A+B above base water EC (1.05 total). Cannazym, rhiztonic and Boost also used. Not currently providing additional PK 13/14. Always PH'd to 5.8
-Water source: 0.05EC rain water
-Strain and age Sweet Seeds Sweet Gelato Auto - Week 10
-Climate: 24/0 light. c. 22c and 50-58% humidity
- Light used: Half of an SP150 - 45 mols DLI. 600 PPFD
-Additional info: Started showing slight signs of this deficiency whilst being given its Pk13/14 dose for a week (as per Canna schedule), though the issue has continued after I stopped this phase.

This appears like a K deficiency but I have not suffered this extent of a deficiency while using Canna Coco nutes to their feed schedule? It is definitely not a PH issue as I check this is to 5.8 every time. This is the most trichome-dense plant I have grown yet, so i'm hoping it's just K-hunger is just a reflection of that?

Thank you

 

[Delty]

Any thoughts or suggestions? I have added a small amount of pk13/14 but reducing a and b slightly to maintain EC. Buds are doing well but I think the def (if it is that) is still progressing slowly

many thanks in advance for any thoughts

 

[tronN00dles]

I’ve had better luck feeding closer to 1.1-1.2ec myself.

What are you using to measure pH? And is it calibrated? I typically shoot for 5.8-6.2 and purposefully bounce around that range rather than 5.8 every time. Also, if your pen isn’t good quality or isn’t calibrated, 6.0 might be a safer target in case your readings are off a point or two.

And do you track VPD? At that humidity you’d be better off if you could get your temps closer to 25 deg C.

Anyway you look pretty far a long so you’ll be seeing a natural fade soon anyhow. Nice job

 

[MIAutomatic]

Looks like you might need to add some calmag and up the A/B slightly. Canna coco line assumes a base water of around .4 but it will work in the range of .2-.6 as long as you adjust accordingly. If your base water is rain water you should be adding a minimum of 100 (.2 EC) ppm calmag before mixing your nutrients. I always start with .4 EC, also using Canna coco and nutrients and my feeding ranges from .6 EC during the first week and I top out at about 1.4-1.5 during peak flowering. I back off to 1.1-1.2 for ripening and finish them between .8-1.0 for the last couple weeks.

Even just adding the calmag might make the difference, it would bring you up to around 1.4. Since your base water is close to 0.0 I would do this:
4 ml/gal Canna calmag before mixing anything else, that should take your EC to about .4
6 ml of A/B gal should take you to 1.2-1.3 EC
The other additives have a pretty minimal impact on EC.

If you don’t know why you need to add calmag then spend some time reading up on cocoforcannabis. They really get into the weeds on the subject, but basically coco uses up more calmag than other mediums leaving less available for the plant. Getting this detailed nailed down is one of the keys to unlocking the potential of coco.

good luck!

 

[Delty]

Thanks for all the input, some really good stuff that I wasn’t fully aware of before. I was aware of the way cal mag interacts with coco CEC but was not that canna coco and and b was tuned for 0.2EC - 0.4EC.

Wasn’t particularly concerned about PH being an issue as I’ve been using the same (Essentials brand) PH meter for other plants and none of them had PH issues. Had ditched using cheap PH pens some time ago

will implement what’s suggested and hope for the best. Thank you!

 

[Del boy]

Hello it looks like you have over fed that girl i never go over a EC of 0.7 using canna as you get lock out by over feeding and what is your run off EC.
These girls where fed a EC 0.7 that was more then enough canna nutes lower the PH in pot over a period of 24hours so your ph has probaly droped below the the range which is giving you issues dont just up the feed thats not going to help it will just make it worse

Here is a chart that shows what happens when nutes are out of balance

I pH 6.2 with canna nutes that way you get better up take

Happy growing you know it makes sense

 

[MIAutomatic]

I missed the bit about the PK, if this happened after you added the PK, then I think Dell Boy is correct that you might have over fed a little. What was the EC when you gave the PK? PK has a huge impact on EC, I never use it at more than 2-3 ml/gallon. I still think you need to add some calmag, but definitely don’t up the A & B. Sorry for missing that important detail, deficiency and overfeeding can look very similar in the early stages, and sometimes happen along side each other due to overall imbalance or PH issues. I don’t think you need to worry about you PH too much since it has a tendency to rise slowly in the medium, but it would be good to check your runoff ph to make sure you are not out of ideal range. Coco will work pretty well between between 5.5-6.5 but the best range is 5.8-6.2.

 

[Delty]

I think it was already showing the def and the feeding PK made no difference, it then got progressively worse. When I did add PK I added 0.2 to 0.3EC worth, with about 0.7EC of A and B ie a far lesser rate than the canna feed schedule.

I have now also added Cal Mag in response to the earlier post saying how Canna Coco nutes are tuned for 0.2-0.4EC water, whereas mine is below 0.1EC tap water.

@Dell boy thanks for your comments. Though I have just harvested a seeds stocker amz which was healthily taking 1.1EC of just A and B, she yielded 180 grams under a 100w Mars TS600, no def or lockout. My Sweet Gelato started showing this deficiency before I even went up to 1.0EC.

the plant has still gotten worse after introducing 0.2EC of cal mag (and slightly lowering A and B).

Is it worth me fully flushing (canna flush) through and if so what should I then feed? 0.7EC a and b with 0.2EC of cal mag?

 

[Delty]

Just tested run off PH - it is 4.5 which seems very low. Just tested the feed again (big can made a couple of days ago) and that’s dead on 6.0PH

 

[Del boy]

Just tested run off PH - it is 4.5 which seems very low. Just tested the feed again (big can made a couple of days ago) and that’s dead on 6.0PH

Hello just flush with EC 0.7 till run off is PH6.1 thats what i would do. And on your EC each plant is diffrent some can take it some cant i have never feed over 0.7 with any autos i have grown but that works for me. The last few grow's i have changed nutes and only feed EC 0.5 from start to finish with no deff at all i dont use cal/mag unless plant needs it.What is your EC run off at ??