Deficiency help. Phosphorous def? Salt buildup?

jdongle said:

-Week 4 or 5 flower

-Growing in happy frog soil

-Fox farm big bloom, grow big, and tiger bloom 2-3tsp/gallon each every other watering

-Plain PHd tap water every other watering

-PH of runoff is around 6.5-6.7

-Seems to be occurring on the upper fan leaves so a mobile nutrient issue?

I’m unsure if it’s locking something out or not. At first I thought it was a nitrogen deficiency so I added additional nitrogen, but it seems to be getting worse.

Any ideas? Thanks for the help!

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CaliRootz88 said:

What size container are they in?
-3 gal fabric pots
How often are you watering?
-When the soil is dry. Maybe every other day to every 2 days. It varies.
When watering how much run off do you have?
-I wait until it starts dripping from the bottom of the pot into the tray. Maybe 5-10% runoff?

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hotrodharley said:

It’s magnesium deficiency. Google it if needed. You’re in the window for calcium and magnesium deficiency at week 4 of flower. Think stretch. Magnesium is a critical nutrient in cell formation. Good feeding and add cal mag. I add at the beginning of flower. I don’t use cal mag routinely. Tap water and most nutrient brands usually supply enough. Until stretch at times.

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jdongle said:

Appreciate the response and it makes sense to me. My plan is to add in some cal/mag to it's next nutrient feeding. I will see how it goes from there.

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Phytoplankton said:

If you’re using the FF trio, you need to do a flush, 3x the volume of the pot. FF nutes are synthetic, I’ll almost guarantee that you have a salt build-up that’s starting to lock out NP&K. With FF nutes you need to flush at least once, usually around the flip, then sometimes about halfway through flowering. I’m a little surprised you made it this far before having issues.

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ALPHA.GanjaGuy said:

my opinion, although I only did one run with them I did not need to flush when using fox farms, I would not suggest you flush with a deficiency unless you want to exacerbate the situation. If you do decide to flush remember to finish it with a weak nutrient solution to not leave them completely starving

I did feed at 25-50% the listed feed rate so maybe that helped.

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jdongle said:

I appreciate the suggestion. It most likely is a salt buildup because I don't water enough to leave much runoff which is a mistake and why I am having to deal with this now. I also can't seem to nail down the exact deficiency which leads me to believe it's several which typically means lockout.

I was fertilizing far too much. Live and learn.

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