Having deficiency issue: need advice please help

[StrongZZZ]

Cherry Kush - Fox farm soil and coco mix- Week 5 in flowering under Mars hydro 4800 4x4. Notes- Dr Earth and some supplements, Cal-Mag and pure blend tea both from Botanicare. Never used Calmag until 2 days ago? Good decision? I'm not a pro but I was assuming Nitrogen Deficiency, plus there is something else going and I have no idea. I'm tempted to flush but it's already 5 weeks into flowering? One day I woke up and checked my plants and within 12hrs overnight the plant turned yellow. The fan leaves were damp and solid neon yellow and it's working down the plant, The yellowing stated at the tip and moved backwards to the cola.. I gave it some more nitrogen and watered with Calmag. Hopefully that will work? I could use some advice here please.

 

[Nunyabiz]

Calcium deficiency, and or root bound.

 

[PlanetJ]

If this was hydro, I would tell you to verify/calibrate your pH meter and then check your pH.
I was thinking Mg, but if you added that, it's likely locked out for some reason.

DISCLAIMER: All my soil grows sucked.

There is this chart regarding what other nutrients the plant needs in order to uptake each nutrient you can give it.
I would suspect based on the little info you gave, there is an imbalance in the medium, causing you issues.

Edit: Liebig's Law of the Minimum

Basically, if it misses one that is lower, everything that is taller, will not be available, or limited.

 

[StrongZZZ]

So Calmag will work? Or just add more nitrogen?

 

[PlanetJ]

If its just a lack of nutrients in the medium, that should solve it. If its complicated (lockout, soil too wet, room to humid or arid) it could be related to that as well. It also doesnt look like this formed overnight to be honest .. must have been building for a few days at least I would think.

What have you been giving them, how often, things like that help. I sadly already bottomed out, but others will chime in for sure.

 

[Roy Growin]

Are you sure that's not tiny spider mites?
Add more CaMg/PK tho N looks a little light too - but if you are already giving lots of nutes, it's pH or over-watering

 

[StrongZZZ]

Definitely haven't had any pest. I'll add Cal-MagPK see what happens and add some N too

 

[Sativa1970]

Mag deficiency works up from the lower leaves first. Nitrogen deficiency effects older leaves first. In flower the demand for Nitrogen is low but the plant is draining the reserves form the older leaves. That indicates no uptake at the roots. It is unlikely all of the nitrogen in the medium was suddenly depleted over night.

Take a teaspoon of the medium out and put it in a small jar. Add a few oz of PHed water to it. Mix then let it sit for 10 minutes. Test the mix PH. If PH is not the source of lockout, high levels of P can lock out N,Ca and Mg. Low Mg can prevent the uptake of N.

The yellow leaves will not return to green. look to the new growth and if the old growth die off ends. Hope she is rebounding for you.

 

[cbdhemp808]

Looking at this from perhaps a different perspective... The plants look close to harvest, so the emphasis for me is to look toward pot size and soil mixture for the future. If you've got sufficient pot size, and a well balanced soil mixture, along with proper watering schedule, and some form of feeding, these problems will go away. I use my own custom made soil mixture based on: compost soil, volcanic cinder (mostly black cinder), coco coir, fresh worm compost from our worm bins, and organic ferts from Down to Earth. The ferts: oyster shell powder, seabird guano, bat guano, dolomite, gypsum, greensand, potassium sulfate. I also add a little biochar if I have some. Of course, all of these in the right ratios.

 

[Phytoplankton]

Couple different things it could be, you’ve got a calmag issue and a need for flowering nutes and a little N too. The question is why? Could be a deficiency or a lockout or a PH issue. At this point, in flower, you don’t have time to mess around with trying this or that. Do a major flush, 3x the pot volume, and reset the soil, then go back to adding calmag and the appropriate flowering nutes, I might try half or quarter veg nutes too, just once after the flush. PH your water after nutes and calmag to about 6.2. That way you’re covered whether it’s a deficiency or a lockout.