Interesting (or weird) Thought/Question on PH

So... we know that if growing in a "soilless" environment, you want to PH to 5.8 or so (I don't grow hydro).

If you are growing in soil, 6.5 or so is the sweet spot.

Is this an all or nothing deal. What exactly makes it a soil grow?

I am not being stupid. I am just not sure what makes soil or at what percent and if a grow medium with less "soil" should thus target a lower PH. Is optimal PH a spectrum from high soil to no soil.

I grow in a mix that is roughly 25% each of potting soil, peat moss, vermiculite and perlite. Potting soil counts as soil. If peat moss does, than 50% at most of my mix is soil. So if no soil is 5.8 and all soil is 6.5, would my plants prefer around 6.15 (splitting the diff to demonstrate 50% soil).

I PH to 6.5 and plants seem happy generally. But this crossed my mind because it seems illogical that we make it black and white.

Thoughts?

I grow in soil mixed with vermiculite and perlite, I go for the 6.2 range myself. Good question though some people grow hydro in just vermiculite. Gonna keep my eye on this one, could get quite interesting!

I use hydro and clay pebbles.
5.2 to 6.2 are the acceptable range (5.8 being perfect).

The pebbles have no nutrition so, I imagine, are similar to straight vermiculite.

Hi Growindad,
Soil or soilless grows strive for a certain ph...as you stated. But truth is, it's damn near impossible to keep things spot on. Even in hydro, there's always a range that you allow before correcting.

Coco is a particular and finicky at times media, and because of it's tendency to lock out Ca++, needs a hydro-like ph.

Make your best guess at correct range, or even better for a nube is to use a medium that is well used and reliable...so they aren't breaking new ground.

Try 6.2 for your mix and watch plants carefully...
Peace,
JD

PH has not been an issue for me. Though maybe i should be going lower than 6.5. Post was more meant as a theoretical as the logic of it being a spectrum for the ideal target makes sense to me.

Anything possessing organic, mineral, rock, and clay particles is technically soil. Even though you are doing no more than 50% soil, you're still considered to be in a soil environment. That said, 6.2-6.3 is ideal in that setting. Only time the pH is supposed to be 5.8 is when you are in a complete hydro environment using nothing more than water or perlite (something that is pH neutral). Anything else that can fluctuate a neutral pH like potting soil or peat moss, typically want a big higher pH.

Any more opinions?

What makes something hydroponic is that all the nutrients are water soluble, nearly all nitrogen is provided as nitrates rather than ammonium or urea.

What makes something soil is that the medium itself is food, but contains many elements as poorly soluble compounds that are slowly brought into the water. (like limestone) Soil naturally contains toxic metals like aluminum that's normally harmless, but a low pH can bring aluminum into the solution blocking out important metals. The majority of nitrogen is fed as urea which is converted to nitrate by bacteria. Bacteria that convert ammonia to nitrate do not like a high concentration of nitrates as that is their waste.

Short answer, it's just different, but I think it makes sense that there's a black and white difference in what ideal pH should be. It doesn't make sense imo to go "half soil" (using hydro nutes in soil).

GrowinDad said:

Any more opinions?

Click to expand...

Dad;

Very intriguing question... got me thinking for sure.

I don't have any answers, just more questions. However, I wonder if the difference could be broken down into how the medium holds/stores/processes the water (or nutrient solution).

I mean I run Hempy buckets right beside my soil pots, and often just feed them the same water @~6.2pH ~660PPM. The hydro buckets will start to show signs of deficiency, so then I just water them separately @5.7 for a few days, then repeat the cycle.

In my soil if I'm to water separately, I find both my moms and my flowering plants very much prefer pH 6.4, which I aim for (often I'm lazy and it isn't exact, but if I get too far off my plants bitch at me and cause me more effort for a few days).

-spek

...just thinking out loud/thinking this through and offering off the cuff speculation, but...

I've read in a few places certain plants can make different types of roots depending on the media....
for certain there are aerial roots and so called "Aquatic roots" ...so it follows there are soil roots, but again I'm not very versed on this thing and not 100% certain what the differences are....

anyway, maybe it has something to do with that or the perhaps way chemicals behave in liquids vs. air vs. oxygen, et et