Recommended PH in Soil/Soilless/Hydro

Just to clarify. After searching for quite a while I could not find a solid answer

Soil: 6.5

Soilless: _ _?

Hydro: 5.9

Should soilless be treated as hydro since it is an inert medium?

Hopefully an experienced person can clear everything up.

The correct PH is related more to the type of nutrients ie organic or chemical, then the type of medium.

In hydro, the optimum is about 5.6 (depends on the nutrients - follow the recommendation of the nutrient manufacturer)

When using organic nutrients about 6.3 is optimal. Basically when growing organically, you want to have a biologically active root-zone. PH being too low will inhibit the microbes and consequently the breakdown of the organic nutrients into usable forms.

good luck

outdoor soil 5.8 to 6.5
soilless mix like pinebark or peatmoss 5.6 to 6.2
hydroponic 6 to 6.5

yep Ezra called it, and for exactly the right reasons. in semi-sterile hydro, hemp will grow well in a pH. that's lower than the typical universal pH. for hydro of 5.8.

Typical university ph for hydroponics (and hydroponics in general)
is 6 to 6.5 This is probably because most hydroponics are grown with vegetable plants that fruit. This usually requires alot of calcium. At lower ph, calcium and magnesium would be less available. I think for mj I would use about 6 ph which is not too low still allowing calcium and magnesium to be available but also would not be too high to interfer with the micronutrients being available and not fall out of solution and oxidize/form insoluble precipitates. This lower ph 6 probably will allow the use of cheap sulfate forms of the micronutrients rather than chelated form. If you do choose to grow at a higher ph in this band like 6.5, you will want to use chelated forms like edta or dtpa of the micronutrients especially iron. Unfortunately, boron can not be chelated.

This is crop-specific hydroponics, and weed is most often recommended below 6. It varies according to crop. here's a non hemp crop recommendation chart:
http://www.gtghydroponics.com/faq/veggieph.htm
And, another crop chart:
http://www.simplyhydro.com/ph.htm
One for fruits, here:
http://www.gtghydroponics.com/faq/fruitph.htm
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Wikipedia's suggestions for Pot:
In soil, the optimum pH for the plant is 6.5 to 7.2. In hydroponic growing, the nutrient solution is best at 5.2 to 5.8, making cannabis well-suited to hydroponics because this pH range is hostile to most bacteria and fungi.

And that's found here, down on the page halfway:
http://en.wikipedia.org/wiki/Cannabis_sativa

N.A.S.A.'s hydroponics' recommendation, but this is for lettuce specifically i think: note it's way below 6. Halfway down the page or so.
http://quest.nasa.gov/smore/teachers/act4.html


Advanced Nutrients' suggestion, also lower than for most other crops: remember they specifically claim to be a Marijuana Nutrient manufacturer. Just below the black and red chart, to the right:
http://www.advancednutrients.com/nutcalc3public/

There are many many more, and some of them might suggest above 6, but as Ezra said, the recommendations for pH above 6 are for organic growing utilizing biological species to augment nutrient - mainly nitrogen - processing.


And soil less is considered hydroponic man, because the nutrient processing is not going to be buffered by microbial action unless you manage the pH. accordingly, and provide enough environment to sustain them.

5.8 Is the Golden pH for hydro period.

I dont think that there is a "Golden ph" as this depends on the type of nutrients used. for example Advanced nutrients recommend 5.6 for use with their formula. I dont think that 5.8 would be better when used with the AN formula (they do test their stuff quite extensively and should know)

"soilless" media can be treated as hydro as far as ph is concerned if using synthetic nutes, or as soil if using organic nutes. the only difference to be aware of with 'soilless' media such as coir is that it can lock up calcium and make it less available.

5.6 to 6.2 in soilless media check out: water, media, and nutrition for greenhouse crops edited by David Reed at Texas A M This book is excellent.

6 to 6.5 hydroponics check out: Hydroponics a practical guide for the soilless grower by Benton Jones at University of Georgia He's kinda old and retired. The book lists all methods of hydro and soilless and alot of "recipes" for nutrient solutions. Really interesting.

Relax, below 5 and above 7 is when the real problems start to occur

ezra has a great point there, listen to the manufacturer when it comes to pH

pH matters in the rootzone, not in the res, so, if you're not in DWC/Aero/Coco, measure the runoff to get an idea of whats the EC and pH in your rootzone.

Remember, pH charts only describe the solubility of a nute at certain pH ranges, not the real uptake.

The stronger the nutes, the lower the pH, since nutes are acidry.
Don't chase pH, let it drift a bit, don't try to correct a low nute strength with lots of pH down or a strong nute strength with lots of pH up.

In hydro, the water with the nutes should set the pH in the right direction (tap water buffered nutes for tap water, RO water buffered for RO), in soil, the dirt itself should buffer pH.
Ver/per for instance will accumulate nutes over time and thus the pH will fall over time.

pH adjustments with pH up/down are only small adjustments, never use both at the same res, its not exactly like tuning a radio, lots of troubes from chasing pH.

for the sake of it here you have some more pH charts: http://www.angelfire.com/cantina/fourtwenty/articles/nutrientavailability.htm

mace

Maybe I can create more confusion. When you measure the ph of soil, soilless mix, or maybe non-flowing hydroponics, you are measuring what is called the bulk ph. The ph surrounding the roots is called the rhizosphere ph. Measuring this ph would be difficult. It is more important. It may be up to 2 points ph difference higher or lower than the bulk ph. Nitrogen source has the biggest influence on the rhizosphere ph. Higher than 8 parts nitrate nitrogen to 1 part urea or ammonia will raise this rhizosphere ph and less than 8 parts nitrate nitrogen to 1 part ammonia or urea will lower the rhizosphere ph. (Nitrate raises ph and ammonia/urea lowers) The real question is what direction the rhizosphere ph is headed. This may be also something to consider and keep in mind when discussing ph. I love plants and I am really high right now.