Soil pH

So been meaning to ask this for a while and keep forgetting. Whats everyone use to maintain soil pH ? Mine is too high. 8 to 8.5. Changing the watering solution to like a 6 does nothing to the soil seems. Need something IN the soil for next time I think. My water is 7.2. and when nutes are added it does not change much so its my soil medium. Thought it was great mixture just need to lower it down to the 6's. Thanks

Did you make the soil, or is it a commercial soil?

HoundsNTrout said:

when nutes are added it does not change much

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What nutrients are you using?

HoundsNTrout said:

So been meaning to ask this for a while and keep forgetting. Whats everyone use to maintain soil pH ? Mine is too high. 8 to 8.5. Changing the watering solution to like a 6 does nothing to the soil seems. Need something IN the soil for next time I think. My water is 7.2. and when nutes are added it does not change much so its my soil medium. Thought it was great mixture just need to lower it down to the 6's. Thanks

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What are you measuring with?

HoundsNTrout said:

So been meaning to ask this for a while and keep forgetting. Whats everyone use to maintain soil pH ? Mine is too high. 8 to 8.5. Changing the watering solution to like a 6 does nothing to the soil seems. Need something IN the soil for next time I think. My water is 7.2. and when nutes are added it does not change much so its my soil medium. Thought it was great mixture just need to lower it down to the 6's. Thanks

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I had some plants in high pH soil recently. I had decided to grow without my usual FF nutes. I compost my own grow medium, which includes about one third composted cow manure, and lots of once used Fox Farms Ocean Forest, so why not save the $ and see if my soil was any good by itself? Everything was fine til about 2 weeks into flower stage. While a plant will naturally rob lower leaves of nutients already made to support faster flowering, my plants looked like they were not gonna survive it. But the flowers looked very healthy. So I checked the soil pH, and it was slightly over 9. Looking at a nutrient uptake chart in relation to pH, I could see where nutrient uptake was inhibited with higher alkalinity values. I started feeding regularly my FF nutes, and they straightened out fine. I promptly added sulfur to my compost for future grows.
Here's that pH chart:

electricthot12 said:

I had some plants in high pH soil recently. I had decided to grow without my usual FF nutes. I compost my own grow medium, which includes about one third composted cow manure, and lots of once used Fox Farms Ocean Forest, so why not save the $ and see if my soil was any good by itself? Everything was fine til about 2 weeks into flower stage. While a plant will naturally rob lower leaves of nutients already made to support faster flowering, my plants looked like they were not gonna survive it. But the flowers looked very healthy. So I checked the soil pH, and it was slightly over 9. Looking at a nutrient uptake chart in relation to pH, I could see where nutrient uptake was inhibited with higher alkalinity values. I started feeding regularly my FF nutes, and they straightened out fine. I promptly added sulfur to my compost for future grows.
Here's that pH chart:

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Seems that is sort of how it went here too Thanks.

HoundsNTrout said:

So been meaning to ask this for a while and keep forgetting. Whats everyone use to maintain soil pH ? Mine is too high. 8 to 8.5. Changing the watering solution to like a 6 does nothing to the soil seems. Need something IN the soil for next time I think. My water is 7.2. and when nutes are added it does not change much so its my soil medium. Thought it was great mixture just need to lower it down to the 6's. Thanks

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How are you measuring the ph of the soil?

Hollatchaboy said:

How are you measuring the ph of the soil?

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I've struggled with this. What is the best way?

electricthot12 said:

I've struggled with this. What is the best way?

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There really is no good way. Soil microbes usually adjust the ph, at the rhizosphere. Ph can be different throughout the medium.

electricthot12 said:

I've struggled with this. What is the best way?

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I believe the only accurate way is checking several locations in the pot with a soil ph probe. They aren't cheap.

If you're using a soil-LESS mix such as Fox Farm or Roots Organic, etc., then you're not really dealing with dirt-soil. Most all of the ingredients in soil-less mixes are inert. Dirt, on the other hand, is full of all kinds of critters and microbes and "stuff" that helps buffer and regulate the pH. In soil-less mixes....not so much. In my opinion and experience, you are better off handling those mixes in more of a hydroponic type way -meaning that you should use a fertilizer regime such as Jack's 3-2-1 or Master Blend's system or similar and pH accordingly. And because it's not really dirt, you SHOULD definitely keep tabs on the pH of your incoming water as well as the runoff.

EDIT: And you can easily check your runoff with the General Hydroponics pH test drops -available on Amazon and cheap! Will it give you and EXACT pH reading? No. Will it give you a sense of the range your pH is? Yes!

If you don't have, or can't afford, a good test probe, a slurry test is your next best option. Take the soil from 3-4 different spots mix it with water to a mud consistency, then use test strips or PH meter.

Even soil less mixes, contain organic material. Anytime you have organic matter, you have microbes, unless you run sterile.

1212ham said:

I believe the only accurate way is checking several locations in the pot with a soil ph probe. They aren't cheap.

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I use Rapitest soil kit, and prepare my sample accordingly. One part soil to 5 parts distilled water. But it doesn't tell much. So I then stick my pH pen in the test water and read that.

Hollatchaboy said:

There really is no good way. Soil microbes usually adjust the ph, at the rhizosphere. Ph can be different throughout the medium.

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I make my own compost, and turn frequently. Have for years. Should be same pH throughout. Lots of well composted (two years) cow manure in there.

electricthot12 said:

I make my own compost, and turn frequently. Have for years. Should be same pH throughout. Lots of well composted (two years) cow manure in there.

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I get that, but plant roots exude acids to make some minerals soluble. The plants themselves can change the pH of the medium, to a point.

When I was growing in l.o.s., I never pH'ed the input water. There's really no need. The soil microbes will adjust to what they, and the plant prefer.

If you're using bottled nutes though, it's a different story.

Hollatchaboy said:

I get that, but plant roots exude acids to make some minerals soluble. The plants themselves can change the pH of the medium, to a point.

When I was growing in l.o.s., I never pH'ed the input water. There's really no need. The soil microbes will adjust to what they, and the plant prefer.

If you're using bottled nutes though, it's a different story.

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I use Fox Farms nutes. I always pH to 6.3. I generally start a new grow with 50% Ocean Forest. My seedlings couldn't take the fungal salad that has developed in my compost over the years. Once established in veg stage though, fungus becomes beneficial, as it is to all plant life..

In my experience, Fox Farm soil less mixes can sometimes come with extremely low pH. On my last run, my plants got sick early on and my runoff showed a pH of 4.0. This suggested there was no buffering going on at all, regardless of whatever microbes may have been present. I essentially did end up running so much high-pH'd water through there to bring it into a ~6.5 range that I essentially ended up with a sterile mix. After that, I started a Jack's 3-2-1 regime and never looked back. Everything grew very well after that.

Phytoplankton said:

If you don't have, or can't afford, a good test probe, a slurry test is your next best option. Take the soil from 3-4 different spots mix it with water to a mud consistency, then use test strips or PH meter.

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Yep. Agreed. Slurry test is a good thing. I did several on my last run and they all were in alignment with the runoff tests.

Peat is pretty low pH.

Elemental sulfur can lower soil pH over time - bacteria consume it and excrete sulfuric acid. Most of the "soil acidifier" products, like for blueberries and such, use some form of sulfur.