Phosphorous Deficiency in Organic Water Only Soil?

  • ILGM Girl Scout Cookies Extreme
  • Method: Organic in Water Only (super soil) with nutrient teas that include worm castings, high p guano, alfalfa, molasses, and liquid kelp & fish. In addition to that I am using Roots Organic Calmag to supplement. One other thing… I did root drench with nftg bloom khaos twice but as instructed I did 6 times that amount with nftg herculean harvest. With this root drench I also included Roots Organic Calmag.
  • Vessels: 5 gal airpots
  • I don’t water to run off but I do ph my water with organic up and down. Always keep the input to between 6.8 and 6.3
  • I don’t check the ppm/ec
  • Indoor
  • QB LED 320W, 18" from canopy
  • Temp is 70F
  • Humidity varies but usually between 40% and 60%
  • 4" exhaust fan with filter
  • No humidifier or dehumidifier
  • No CO2

I’m in week 3 of flower. Everything seems to be going well. I have had just a tiny touch of the claw here and there but overall the plants are healthy. Leaves have been mostly praying for the last couple weeks. I did have a pretty severe calcium deficiency late in veg but corrected it with a nutrient tea (an unexpected positive effect of the tea I think). You’ll see some remnants of that on the lowest leaves.

Now, the question: some of the lower to mid leaves seem to be almost turning bronze, they are a little crispy and kind of taco’d down. It’s not so many that it is alarming at all. Especially considering that overall they look happy. Based on some of the symptoms I’m seeing I think it might be a phosphorous deficiency. Thoughts?

EDIT: Now that I look at the overall pic I’m seeing pretty severe leaf curl at the right foreground. Those are the leaves that are a little crispy and taco’d down.

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I can’t really comment because our growing methods are different, but you’re gonna like the GSC.

Welcome to the forum. Folks with experience in what you are doing will come along shortly.

When doing a root drench you need to water till runoff. I grow in organic soil myself you have to check those P PMs from that runoff so you know if you need to adjust your soil pH or if you can feed them or not based off of your PPM reading. The best way I do it is I elevate all my pots off the ground high enough to be able to fit bowls underneath them to collect samples and test them after their rinse. I found out the hard way when I started burning my plants with that live soil and nutes, I finally checked the runoff and initially it was over 4100 ppm’s

I re-read your post. I’ll do that. Also i water with tap which I let off gas over night but the symptoms could be chlorine (I don’t have chloramine). Oh and I have a Blue lab soil ph probe so I can easily check that any time.


Burnt tips look like nutrient burn. @Budbrother can sort you out.

Yep, the soil I’m using is called “Great Lakes Water Only” it is essentially a super soil but not the exact same recipe.

It is very hot. Most suggest using roots organics only at first then transplant into a pot with Roots Organics at the top and Super soil at the bottom. That way roots can grow into it. Well, I didn’t know about that at the time. They went straight into the super soil. And a week later they were showing pretty severe claw. Like 90 degree angle tips pointing down. I knew what it was right away and confirmed with others that Roots Organics should also be used. The soil manufacturer suggests using teas and gives recipes for them so it shouldn’t be that (but it probably is). It’s probably been 10 weeks since they were in the 100% super soil pots. Now they are in the combo of both soils.

Could accidentally splashing a full strength nutrient tea on some leaves here and there cause the bronzing lower leaves? I definitely splashed and didn’t dry the leaves after more than once. Or I’m thinking chlorine is there a way I can check for its presence after 24 hours? As far as the claw maybe it’s unrelated and it’s just too much Nitrogen?

Tonight I will water ro runoff with just Roots Organics Calmag and check PPM and pH.

Phosphorus def will hinder a plant’s ability to manage temperatures at canopy and the result is brittle, burned leaves and a bronze tint.

As you are growing in organic soil there isn’t too much you can do quickly to rectify the problem. One thing you really need to do is flush and monitor runoff TDS/PH to keep plant in the zone. Not watering to runoff means waste salts collect in soil layer/root zone and can cause lockouts like K def you have now.

Flush and take a runoff TDS/PH.

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I don’t use salt based nutrients. All organic (I don’t even use Botanicare’s CalMag+ because it’s salt based). No salt build-up at least that’s my understanding from everything I’ve read. Also, flushing super soil is very drastic since you are washing out all of your nutrients. Generally the beneficial organisms are responsible for breaking down the nutes and making them available to the plant. This makes nutrient burn less likely (but clearly doesn’t kill the problem entirely).

Caveat: I’m newish to all of this but I’ve read a lot lot lot like many of us have.

With ALL of that said, I might end up flushing but in the meantime I’m going to try some other things. I might layoff everything except water and calmag for a couple weeks to see what happens. Then I can resume again if that alone remedies the problem.

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You got a problem. That’s how you deal with it. The plant itself exchanges waste elements (sound better than salt? :smiley:) which can build up in the root zone and cause issues like you are having.

If you truly want ‘all natural’ then just let the plant take it’s course.

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Okay. I didn’t mean to argue. Sorry. I guess I just wanted to make sure salt buildup was a possibility in a salt-free organic grow. So, I’m going to try a couple things before flushing. 1) check soil pH, 2) check ppm of input, 3) check ppm of runoff.

I’m going to try some “Recharge” and some SLF-100 tonight. What do you think?

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I think that’s a great plan.

The results are in…
I watered with dechlorinated tap with SLF100 and a product similar to Recharge (store was sold out).

Input: 225ppm, ph 7.0 (I kept it high because my soil probe told me ph of soil was 5.5)
Runoff: 2510ppm, ph 6.5

I’m going to ride it out for a week and see what happens.

Any input welcome.

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You’re wise to ride it out. I’d water only until the ppm’s get back where you want them.

Over the course of time using super soil I’ve learned the plants are normally pretty good until after the stretch into the first week of flower. Then it’s time to add extra nutes to continue healthy growth.


The soil I use is basically super soil but store bought and made by a local company. The goal is water-only like you said. My question is, what size pot do you use? The maker of the soil I use recommends 7 gal with the idea being that there are enough nutrients in 7 gallons to finish the average length grow with no supplement. Right behind this grow that I posted about, I have another grow in veg – same soil but with 7 gal pots.


I use both 7 and 10 gallon pots. I’ll tag you to my journal. I’m starting to grow with living soil now. At the beginning of my journal there are several super soil grows.