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,,rust" spots advice needed

UglyEart
UglyEartstarted grow question 21h ago
Hey growmies, I just noticed my big girl developing rust spots. 🤔🧐 I will up the calmag a bit and see if that works, 👍 but I'd also appreciate some experienced advice before I do anything else. 🙏 Thanks a lot 🙌
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John_Kramer
John_Krameranswered grow question 14h ago
Organoman over feeding with what pray tell ?
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Organoman
Organomananswered grow question 14h ago
Burning from over feeding............pure and simple. It has nothing to do with cal/mag or a P deficiency.
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John_Kramer
John_Krameranswered grow question 16h ago
yep P,Ca deficiency
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MrGrowDiarie
MrGrowDiarieanswered grow question 18h ago
Cal mag and the problem is gone ! :)
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00110001001001111O
00110001001001111Oanswered grow question 18h ago
could also be low P or something locking P out. coco-mix? is that soilless? If Ca ppm have been 100+ in your fertigations, i'd lean P ... P is fine around 40-60 ppm -- again, this assumes soilless method of growing and fertigating every irrigation with 10% runoff. if it is soilless and not religiously stickign to the 10% runoff minimum, then i'd look into lockout. Download an image of "mulder's chart" to see all the possible causes of lockout due to levels of other nutrients. The clarity of dealing with problems of a proper soilless or hydro grow makes things easy. More fog of war if you have to consider what amendments are adding to the mix, too. Calcium should be part of the full and complete diet and not just added here or there. Your tap water may impact exactly how much you need to add to avoid deficiencies and toxicities....
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Growtendo64
Growtendo64answered grow question 21h ago
It could definitely be CalMag-related – the rust spots are a classic sign. But before upping the dose, check the pH of your runoff water to make sure your plant can actually absorb CalMag. In soil, aim for a runoff pH between 6.2 and 6.5. Even if you’re feeding the right amount, a pH imbalance can block uptake. Also worth checking: salt buildup in the soil or excess potassium can interfere with calcium/magnesium absorption too. If in doubt, a light flush and recalibrating your pH and feeding might help! You’re on the right track – just dial in the details and your girl will thank you.
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