Advice on Potassium deficiency

A couple weeks ago I notice a few lower leaves getting very dark and falling off. A week ago I researched it as it started to increase and move up the plant. I believe it’s potassium deficiency along with pH being too high. Quick checks on this site indicate lower the pH and use something like Fox farm big bloom and all should be well. A week of that and I feel as though it’s continuing to spread, I don’t think I’ve arrested the issue. Example leaves below. Some as far up as the top of the plant. I ordered a pH tester and I will get more precise with that starting tomorrow when it arrives. pH usually about 7 here. Bergman Gold Leaf, 18 days into flowering. Was Very healthy prior to this. Thoughts or advice? Talk me off the edge please. :).

This is

would be helpful if you would fill out a grow sheet. knowing all the factors is important.
especially…soil, coco, or dwc? ph range is different for soil and dwc.

Here ya go! Good luck!

  • What strain, Bergman Gold Leaf Fem.
  • Method: Soil - Fox Farm Ocean
  • Vessels: Grown in a small pot, moved to a 10 gallon pot many weeks ago. Same soil.
  • PPM/TDS or EC of nutrient solution if applicable. Fox Farm Big Bloom started June 4, today is the 14th. First signs of black leaves started maybe May 20.
  • Grown in outdoor shed.
  • Light system. Viparspectra V450 LED
  • Temps; Day, Night. Day @ 80 Night at 65. for the past couple weeks. Up from from 55 at night and 65-70 day.
  • Humidity; Day, Night. Between 20-40
  • Ventilation system; Med sized fan blowing to move air into and around in a large shed, small fans blowing on the soil. Windows open.
  • AC, Humidifier, De-humidifier, None.
  • Co2; , No

[quote=“Jbum, post:3, topic:32199”]

@tanlover442 I had to google DWC… I had No idea on that one. On a lot of this actually. :slight_smile:

So you’re not measuring ppm or pH?

You started this inside and moved outdoors? What’s your lighting schedule? She’s flowering.

I don’t typically use fox farms nutes, but I had some big bloom sitting around. When I added it to distilled water it raised the pH.

It’s been inside the entire time. Winter never let up, so I switched my plan and went full tilt on the big shed. Lights are now 12/12
pH measure by spa sticks so far, real tool arrives soon. Monday I suppose. Parts per million? Not sure what to look for there. :slight_smile:
But I do know the water here is just above 7 typically. I let that sit a day or 3 in a bucket to clear out the sanitizer. Added pH down to get it in the 6 range but that’s a sloppy number I know. She’s 18 days into bloom and looks great aside from this issue. Thank you @Drinkslinger for taking a look.

@Drinkslinger it didn’t occur to me that Big Bloom would raise the pH. I just tested, it looks to have gone up .6 That, with my silly test strips. And yes, she’s blooming big time.

She doesn’t look too bad. But getting your pH under control is imperative. Some people are lucky and get it right by accident.

Do you test the runoff after watering?

Always test pH of anything you give her right before you pour it in.

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@Drinkslinger. Deal. That begins on the next watering. What’s the range I should see there?

No idea where you’re at. But ideally pH 6.2-6.8. With pH 6.5 the sweet spot for soil.


take your ph readings in the run off after you water.

Ok @Drinkslinger and @tanlover442 pH tool in hand - I just added 6.45 water to soak the entire plant and when it started spilling out the bottom I measured that. I got a plus .3 increase. Now at 6.75. Does this mean I should add 6.2 next time to get the 6.5 out the back side? And keep doing this each week maybe and adjust accordingly?

Entire plant, photo taken outside. She’s too tall for the shed and light so I had to train it… this community sure is helpful. :+1:t3::+1:t3:


pH 6.7 isn’t horrible. But you’re correct about the next feed/water. Reduce that to pH6.2-6.3 and see where your runoff is.


@Drinkslinger. Cool - I can work with that. :+1:t3: Prior to using pH down, I was starting at 7 and maybe the soil brought me to 7.3(?). Thank you for your time and help.

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What they said…

OK. I am legally blind but, that looks like water marks. Do you foliar spray your plants?

Foxfarm nutrients drop the PH drastically and generally require PH up before adding to your plants.

I am sorry for the delay in answering this topic but, I had a greenhouse collapse over a week ago and have been busy trying to save all my expensive Citrus and produce. Let me know if I can help. lw

Hey @latewood !! Yes I sprayed them. With a batch of compost tea (Red Frog Compost Tea). My water starts about 7.2ish. Fox Farm Big Bloom increases the pH about .3. Those are my numbers but I’m brand new at this pH thing. :wink:

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I have 7.0-7.2 well water. When I add a full dose of Foxfarm, the ph is
lowered to 4.7-5.2

It actually lowers the PH per tsp. full. I have even talked to the
Foxfarm guy (I have his direct # but,so do many others) 2-3 times and
he admitted that the nutes dropped the PH according to dosage. Now. We
are all thinking these days that better tasting and more potent pot is
achieved with lower PPM. Who knows.

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