Two Plants; Different pH Levels

algebraist

Well-Known Member
This was a surprise. I have two plants that have been treated exactly the same. One has been doing slightly better than the other all along, which I think is natural -- different individuals. Recently the one doing better developed what I think is a potassium deficiency (see http://rollitup.org/t/potassium-deficiency.936130/ for details and pictures). Today I fertilized ("Botanicare Pure Blend Pro Bloom Soil Formula" (1-4-5)) and tested the pH of the runoff. The plant with the possible deficiency: 5.5. The other plant: 6.2.

(They're in soil; almost 4 weeks into 12:12; Northern Lights.)

So: Maybe the low pH is the cause of the trouble for that plant, and I will see what I can do to raise it a little. But that's a pretty big difference. Can it be because the plant, growing faster and so using up more nutrients from the soil, changes the pH of the soil itself, making it more acidic? Or do I distrust my readings and decide testing the runoff is not accurate enough? (I also mixed some soil with water and tested the pH of that after letting it sit -- just for the one problem plant, though: 5.8. That method seems worse to me, though, because it has to be very dependent on the ratio of soil to water -- use more water, you have to get a reading skewed towards the pH of the water, about 7.)

Thanks.
 
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