Potassium deficiency ?

[Dutchman1]

A few brown spots started cropping up the last two days. Im guessing its a potassium deficiency. 5 Plants are in FFOF soil and only been in it 2 weeks or so, so there should be plenty of good stuff left in it. They have grown beyond the edges of the pot though so roots should be to the pot edges also. They have been given a light dose of Cal/mag every other watering. No nutes until today. I just gave them a 1/3 dose of FF trio. PH out was 6.3-6.4. Plants are about 7 weeks old but were badly light burned and didnt start coming back until 2 1/2-3 weeks ago. Lights are at 28 inches. Small fan rustles the leaves lightly. Temp 67-82. Humidity 28-45%. 5 plants all in the same conditions. This is the Critical Kush and the only one with these brown edges.

 

[DoctorJohnson]

FFOF (Fox Farms Ocean Forest for those who don't know the lingo) is a premium soil and, I understand, a hot soil, so I'm going to guess that you don't have deficiency but probably a slight excess, and one that will clear up on it's own if given a chance, meaning you probably don't need to be fertilizing yet and the fertilizing is going to make things worse. I'd suggest going with just water for now (and maybe putting a 13x9 baking dish in the air flow of your fan to increase the humidity a little? Not related, just commenting).

 

[Dutchman1]

Thanks, you might be right. Ill know soon since I gave them 1/3 nutes today.Ive seen nute burn from Fox Farms soil beore but never on such developed plants. These are past the edges of the pots and very healthy. Oh and I have a humidifier in the room and wet towels occasionally but its there in the heating room for the house so it sucks the air out constantly. Humidity really drops when its cold out and the heater is running alot.

 

[Dutchman1]

This is what they look like after two weeks in 5 gallon pots. Actually a little bigger now as these pics were taken a cpl days ago.

 

[Dutchman1]

One other thingI forgot to mention here Doc. I add about 20-25% coco coir and 10% perlite to the soil. This eliminates some of the " hot " and helps with drainage.

 

[DoctorJohnson]

One other thingI forgot to mention here Doc. I add about 20-25% coco coir and 10% perlite to the soil. This eliminates some of the " hot " and helps with drainage.

That's great. I think that should make a really nice soil (but you're going to have to water it a lot, I'll bet). I'm still betting on excess, not deficiency.

 

[Dutchman1]

Every three days I water. Ill keep posting to let ya know what happens. Thanks for your advice.

 

[Dutchman1]

Hey Doc, you were right. I should have known better. Anyway, the 1/3 strength nutes just made it worse( a little) and now several of the plants are also clawing and are dark green from too much nitrogen. We smother our plants with love........

 

[DoctorJohnson]

We smother our plants with love........

I"ve done that. Somewhere I read a clever summary of what plants need to thrive and one of the items was just to be left alone.