The ubiquitous Brown Spots post...

[ColoradoHighGrower]

Any ideas? This started about 1-2weeks ago about 4" below tops of two out of four plants, and seems to have migrated up towards newer sugar leaves a little bit. All inter-veinal necrosis, no excessive purple stems. Cal Deficiency? Mag? Phosphorus? @Renfro @hotrodharley @go go kid @MICHI-CAN @Wizzlebiz (sorry for callouts, saw you guys in my "brown spots" searches)

5&7gal fabric pots
water+feed every ~2days currently
Tap water, .2ec
even parts coco/sphag/promix/perlite/castings
week 5 12/12
2x315w lec @~26"
78-82°F
55% RH
Good airflow & exhaust

Ph seems to always self-buffer nicely to low 6s/high 5s with the FF nutes, using GH drops Ph test kit, so I never adjust. Have been feeding mainly Foxfarm trio, currently:
2ml triger bloom(2-8-4)
3ml big bloom(.01-.3-.2)
2ml bembe(0-1-3)
2ml calimag(1-0-0)
just a touch of big grow (3-2-6)

Have been fairly light with feed applied every watering at ~0.9ec to runoff. I bumped it up last night to 1.1ec adding extra tiger bloom and calimag to see what happens. Otherwise everything looks good and they seem happy. I did have a recent F-up where i let them dry out fairly well, but bounced right back in ~30min after watering with just some minor lower leaf die off.

 

[hotrodharley]

It appears almost potassium and magnesium deficienct. Leaf edge coloration potassium deficient. But magnesium can do the same to the edges and cause the fading between veins.

 

[Nutty sKunK]

Any ideas? This started about 1-2weeks ago about 4" below tops of two out of four plants, and seems to have migrated up towards newer sugar leaves a little bit. All inter-veinal necrosis, no excessive purple stems. Cal Deficiency? Mag? Phosphorus? @Renfro @hotrodharley @go go kid @MICHI-CAN @Wizzlebiz (sorry for callouts, saw you guys in my "brown spots" searches)

5&7gal fabric pots
water+feed every ~2days currently
Tap water, .2ec
even parts coco/sphag/promix/perlite/castings
week 5 12/12
2x315w lec @~26"
78-82°F
55% RH
Good airflow & exhaust

Ph seems to always self-buffer nicely to low 6s/high 5s with the FF nutes, using GH drops Ph test kit, so I never adjust. Have been feeding mainly Foxfarm trio, currently:
2ml triger bloom(2-8-4)
3ml big bloom(.01-.3-.2)
2ml bembe(0-1-3)
2ml calimag(1-0-0)
just a touch of big grow (3-2-6)

Have been fairly light with feed applied every watering at ~0.9ec to runoff. I bumped it up last night to 1.1ec adding extra tiger bloom and calimag to see what happens. Otherwise everything looks good and they seem happy. I did have a recent F-up where i let them dry out fairly well, but bounced right back in ~30min after watering with just some minor lower leaf die off.

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View attachment 4872869

Were the brown spots there before it dried out that one time you mentioned?

 

[MICHI-CAN]

What Harley said. Only as he won't.......Raise the PH of water to 6.4-6.8. All the hydro lore of low PH does not apply here. LOL.

 

[ColoradoHighGrower]

It appears almost potassium and magnesium deficienct. Leaf edge coloration potassium deficient. But magnesium can do the same to the edges and cause the fading between veins.

Thanks! Yes, i think I'm seeing some improvement already since last feed with some extra calimag and bloom/bembe, so this makes sense. Too early to confirm though.

 

[ColoradoHighGrower]

Were the brown spots there before it dried out that one time you mentioned?

Had just started before my unintentional "simulated drought stress experiment."

 

[ColoradoHighGrower]

What Harley said. Only as he won't.......Raise the PH of water to 6.4-6.8. All the hydro lore of low PH does not apply here. LOL.

So.... you like higher ph in soiless coco mixes? I usually target about 6-6.4 and has seemed to work out fine. I'm thinking they were just hungry in this particular case, but too early to verify still. Seem the same, if not a little better.
I should probably go get some Epsom salts and start using that occasionally as well.

 

[MICHI-CAN]

So.... you like higher ph in soiless coco mixes? I usually target about 6-6.4 and has seemed to work out fine. I'm thinking they were just hungry in this particular case, but too early to verify still. Seem the same, if not a little better.
I should probably go get some Epsom salts and start using that occasionally as well.

When I'm trying to resolve nute issues I do. An adjustment is easier than re formulating your feed. I would follow the normal PH rules if going well though. Plants are more picky than cats and women. Odd the things they respond well to. LOL.