New Grower Magnesium deficiency? Week 4 of flower /FFOF soil

[Norcal]

Day 60 from sprout. First time ever grower here and think I have a magnesium deficiency (Blueberry Auto) but would like thoughts from others here. I have been feeding 5ml of CalMag per 1 gallon of RO water for last month. Do I increase CalMag to say 7ml or feed Epsom salt in addition?

Or maybe its just the plant using up old fan leaves and I shouldn't worry given appearance of the plant overall? Could it be a nitrogen deficiency this late in flower? I'm in 4th week of flower.

Indoor grow in 5 gallon fabric pot using FFOF soil, runoff PH is 6.7 with last PPM reading at 1,680. Feeding 5ml per gal of Tiger Bloom and 5ml per gal of grow big. Schedule is water/feed/water and PPMs' typically stay between 1,000 to 1,600. I have NOT done their "sledgehammer flush" but I do water until about 15% run off each time.

More info on my grow listed below pics. Please let me know your suggestions on how to correct or do I just continue with CalMag doses as noted above.


Blueberry Auto from IloveGM
Method: Fox Farm Ocean Forest Soil
Vessels: 5 Gallon fabric pot
PH of water going in is 6.9/ Run off = 6.7
PPM/TDS = 1,680
Indoor = 4x4 grow tent in garage
Light system = 2 ES 300 LED's at 100%
Temps; Day = 75F; Night = 70F
Humidity; Day = 50%, Night 45%
Ventilation system; 12" oscillating fan on wall
deHumidifier = set to 45%
Co2 = No

 

[Hypathetical Gardener]

Im not sure how old the plant is (since sprout) but it appears to be doing really well. Personally I'd cut those dying lowers off and continue on schedule.

 

[BCBudlady]

Agree will HG, you’ve got about 3+wks to go. Overall, your plant looks outstanding. I would just continue your feed schedule as is , for another week or two and then just water to finish. Great first plant! You may consider stepping up the Cal-Mag on your next grow, when the plants hit flower. LEDs and COBs require more Cal-Mag.

 

[Norcal]

Thanks guys will follow your advise! Added to original post that I’m 60 days from sprout.

Still learning to read the leaves, but this forum has been great for researching items I am uncertain about. I have 3 other plants in the tent and looking forward to harvest.

I’ve never even tried growing any type of plant before this so I’m happy with where they are at. Next grow I’ll try LST and defoliation

 

[Proph]

Thanks guys will follow your advise! Added to original post that I’m 60 days from sprout.

Still learning to read the leaves, but this forum has been great for researching items I am uncertain about. I have 3 other plants in the tent and looking forward to harvest.

I’ve never even tried growing any type of plant before this so I’m happy with where they are at. Next grow I’ll try LST and defoliation

Ok.. Not to be a party pooper but please do not do what was recommended. Not trying to step on any toes.. Just trying to get you on the right path..

A few things first.. Removing the damaged leaves will cause the issue to spread faster. The plant is now trying to feed off of the leaves and relocate nutrients to help other parts of the plant. This is happening because there is a problem in the soil that is preventing the plant from feeding on the nutrients you are using.

Based on that 1500 ppm number, and the constant over feeding of cal mag, I'd say you have a nutrient lock out in the soil. This happens when one or more nutrients are in excess in the soil. This causes other nutrients to not be available to the plant, so deficiencies start showing.

Here is a basic chart...

Too much calcium, will lock out magnesium, potassium, boron and even nitrogen. Too much magnesium will lock out calcium.. It gets tricky.. But since your issues are starting at the bottom and moving up the plant (immobile nutrients) and based on the coloring, I'd say too much calcium is locking out potassium and nitrogen. With 3 or more weeks left, you can try to flush those ppms down to a normal range to try to stop the spreading.. But doing nothing is never the correct answer. And 99% of the time adding more cal mag is never the right answer as well.

You posted because you were concerned about your plants.. Which you should be.. You will want to get in the habit of addressing every issue as soon as it starts. Especially with autos because they have zero recovery time.

You did a great job getting this far.. The final weeks are the most important weeks.

 

[Norcal]

@Proph i appreciate the input, never realized over feeding one nutrient could lock out another. Will keep the charts with my other printouts.

Since I’m using RO water, do you suggest PH adjusted watering with NO calmag at all until PPMs are below like 1,000? Or do you suggest a full on flush with like 5 gallons PH’d water? Sorry I’ve never flushed before so not sure on specific steps.

i have not cut off the dead leaves, only tucked them away so that bud sites are exposed to lights.

Final question, when looking at “ new plant growth” to see if a change helps, where on plant do you look? At sugar leaves or fan leaves at top of plant? I’m not sure where new growth occurs.

Man so much to learn!! Here is calmag I’ve been using

 

[Proph]

@Proph i appreciate the input, never realized over feeding one nutrient could lock out another. Will keep the charts with my other printouts.

Since I’m using RO water, do you suggest PH adjusted watering with NO calmag at all until PPMs are below like 1,000? Or do you suggest a full on flush with like 5 gallons PH’d water? Sorry I’ve never flushed before so not sure on specific steps.

i have not cut off the dead leaves, only tucked them away so that bud sites are exposed to lights.

Final question, when looking at “ new plant growth” to see if a change helps, where on plant do you look? At sugar leaves or fan leaves at top of plant? I’m not sure where new growth occurs.

Man so much to learn!! Here is calmag I’ve been using
View attachment 1169529

It's a never ending learning process, lol. Buckle up! You can flush down to 1000 ppms or lower.. It wouldn't hurt. Use plain RO water.. Just take your time and slowly use like a gallon Every 30-40 mins until the ppm reading is normal.. A few days later feed at half strength without the Cal mag, and watch how the plant reacts.

The issues your plants have seem to be with immobile nutrients.. Which means it effects the older (lower) leaves first and works it's way upwards. A mobile deficiency starts at the newer (top) leaves and works it's way downward. In your case, watch the lower leaves with no issues and make sure they don't start showing the same problems. If the flush works, it will slow down or stop the spreading of the issue. You can also use a foliar spray to get certain nutrients directly to the plant. You can search for potassium foliar to get an idea of options.

 

[beachbuds]

Was reading through this post and fully agree with @Proph about not removing leaves and getting on top of any deficiencies/lockout/toxicity issues ASAP. However, in case it’s still relevant as I know this almost 2 months old now, there seems to be a switcheroo with Proph’s description of mobile vs immobile and where they originate on the plant. Mobile issues (N, P, K, Mg) affect older leaves, start at the bottom of the plant and move up as they progress. Immobile (Fe, Cu, Mn, S, etc...) start at the top affecting newer growth and move down. This is a very key relationship to get right as one is learning to read plants.

Good reference here and the source of figure I attached. https://www.canr.msu.edu/news/identifying_nutrient_deficiency_symptoms_in_field_crops