Phosphorus deficiency? Red/purple stems leading up to effected leaves

Ok I have been doing a ton of reading. My one auto continues to have the lower original leaves take on damage. Also noticing purple/red tinted stems leading to those leafs. Noticing the same damage trickle into afew of the sugar leaves and newer foilage now. Wish i would have kept a picture of several of the leaves i pulled earlier today. So if it is a phosphorus issue whats my best way of addressing it without causing nutrient burn in other areas. My plant doesnt quite seem ready for watering. Almost believe that i slightly overwatered at some point and thats caused my current issue.

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Some plants do get red stems its not necessarily a phosphorus deficiency it can be a genetic trait of that strain and it looks like u have a calcium def with those spots on ur leaves a phosphorus def looks like a potassium def they both look very similar they will start around the edge of the leaves and then they work there way inwards

I feel like im chasing my tail. So is the calcium deficiency mobile?

If she’s deficient in phosphorus, providing phosphorus is the best solution. Dicalcium phosphate is readily available in bone ash. It’s also organic so it takes some time to breakdown and become bioavailable. I’d suggest a fast acting source of phosphorus as an alternative - I use monopotassium phosphate, as it supplies P and K, both of which are in much higher demand during flower than the N you needed in veg. It also doesn’t contain any N, so it’s fairly safe.

The brand of monopotassium phosphate (MKP) I use is Mother of All Blooms (MOAB for short), but other products out there are substantially similar: Flower Fuel, Beastie Bloomz, probably others. Tricalcium phosphate may also be a good avenue to provide just phosphorus (and calcium, likely) to your plant if you’re concerned she may not need the extra hit of K that comes in MKP.

Thanks for the information. Im still zeroing in on what deficiency im dealing with. Im thinking i overwatered this auto at some point and are dealing with issues on the backside. Whatever the issue im dealing with its mobile with all the issues starting on older bottom leaves first. Its calcium or phosphorus from what im seeing. My next issue is my plant is still holding some water moisture in the pot today makes 6 days since last water. Im worried about trying to treat the deficiency adding more water to a plant to apply needed nutrients

Phosphorus was my inclination. Reason being those large bronzing patches - this photo here

red circled spots are what I mean by the “bronze patches” - blue circle is telling me she’s got red stems, which is sometimes just genetics and sometimes also indicative of phosphorus deficiency.

The purple circled spots are where I agree a calcium issue is at play.

Think of it this way - your plant isn’t going to be deficient in just one thing, especially if the deficiency is triggered by a phase of plant growth (I.e. transition from veg to flower) because her nutrient needs are changing. Flowering is intensely heavy on P and K, which have a very symbiotic relationship to Calcium and Magnesium. Especially true if you’re hammering her with lots of light, because she’ll want to grow more/faster and eat more.

Magnesium acts as a phosphorus carrier in plants

high Calcium levels can reduce the availability of Magnesium, while greater Magnesium levels can induce calcium deficiency

The Ca/Mg ratio in the leaves of some plants is about 2:1, which means that it is necessary to apply greater quantities of calcium than magnesium via the nutrient solution.

Okay - that was a series of vague quotes taken from a variety of articles. I don’t know why it doesn’t get taught in Canna Gardening but there’s a relationship between P, K, Ca and Mg. Particularly, Mg helps absorb P, and Ca helps everything. If you’re seeing both phosphorus and calcium deficiency, it’s likely that one of two things is true: either she’s been undersupplied Ca and P, or she has an excess of K. I’m not really leaning heavy toward the potassium excess, but it’s worth mentioning that it’s possible.

Consequently, I would aim toward a nutrient that has P & K, higher on the phosphorus (like monopotassium phosphate) and supplement with a CalMag product that has a 2:1 ratio (more calcium than magnesium) to help your plant absorb it all faster and easier.

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Great response mate, I can tell you have done some homework. I have some sensi cal-mag now i need to find the PK. Looks like ill have to order it one way or another.

I wouldn’t rush into watering more if shes still wet after 6 days.

You could be right.

This is why i suggest that you wait and see how she does. Let her dry out a bit. Under and over watering can cause issues.

Are you still using the Old Trucks organic fertilizer? The fertilizer will require some life in your soil in order for the nutrients to be available to your plants. If your sticking with organics and you need more calcium, I would try gypsum for immediate calcium needs, once she dries out.
What week of flower?
Hope that helps, good luck

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Yep im going to wait till she starts looking thirsty. When you say the fertilizer will require some life in the soil. What exactly would that be? Yes im still using the old truck fertilizer currently untill i find something better for these autos.

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Various organisms in soil like fungi and bacteria that turn organic matter into plant absorbable nutrients.
The fertilizer your using has good mycorrhizal fungi and other good organisms to help accomplish that. Happy frog is good soil too in my experience.
I think she looks good. A few spots are to be expected especially with under and over watering. If spots progress after watering practices are corrected then tag some help in.
You should think about starting a journal and posting progress and questions.

Heres a chart that you may find helpful @Graysin


Ill definitely do that in the in future as far as the journal. My first grow i never expected that i would need so many things in my tool bag.

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How about filling this out so can make a more detailed and accurate diagnosis…

COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

-What strain, Seed bank, or bag seed (photo or auto)
-Age of plant
-Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
-Vessels: Type and capacity of container (fabric, plastic, etc)
-PH and TDS of Water, Solution, runoff (if Applicable)
-PPM/TDS or EC of nutrient solution if applicable
-Method used to measure PH and TDS
-Indoor or Outdoor if indoor, size of grow space
-Light system List brand and wattage/spectrum
-Actual wattage draw of lights
-Current Light Schedule
-Temps; Day, Night
-Humidity; Day, Night
-Ventilation system; Yes, No, Size
-AC, Humidifier, De-humidifier,
-Co2; Yes, No

If growing Hydro some additional questions:

-DWC? RDWC? Autopots? Ebb and Flow? Other?
-Distance of liquid below net pot (DWC)
-Temperature of reservoir
-TDS of nutrient solution
-Amount of air to solution

Always try to upload a clear picture in white light of any issues you may have to allow the community to assist you.

Saved that so fast you wouldn’t believe it. Much more concise way of stating my general thoughts.

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What strain, Seed bank, or bag seed (photo or auto) Blueberry x big bud auto
-Age of plant - broke the surface 8/9
-Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF - fox farms Ocean forest
-Vessels: Type and capacity of container (fabric, plastic, etc) 4 gallon wide plastic pot
-PH and TDS of Water, Solution, runoff (if Applicable) not sure
-PPM/TDS or EC of nutrient solution if applicable
-Method used to measure PH and TDS
-Indoor or Outdoor if indoor, size of grow space
-Light system List brand and wattage/spectrum - unit farm UFS3000 x 2
-Actual wattage draw of lights - 200 watts x 2
-Current Light Schedule was a 18/6 but my other blueberry auto is stubborn so switched to a 12/12 cycle
-Temps; Day, Night lights on temps 77-85 off 63-74
-Humidity; Day, Night daytime 41-47 night 55-60
-Ventilation system; Yes, No, Size ac infinity 6 inch
-AC, Humidifier, De-humidifier, running ac from vent through ductwork, cool mist humidifier
-Co2; Yes, No - no

Some updated photos on my autoflower battle.

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