Soil pH Guide

[DrMike27]

Just got a pH test kit and it had this nice insert showing various plant pH preferences and thought I’d share. I think it’s nice to have all these in one location.

 

[DirtMechanic]

That is a pretty good list. I think I am fairly lucky to have generally acid soil in some ways. Trilliums for example grow naturally here. What kind of tester did you get that had so much swag come with it?

 

[DrMike27]

It was a Luster Leaf rapid test kit. For 15$ I thought it was worth it...and I’m hoping it’s accurate because it gave me a pH of 7.0. I was a little worried because I’m planning on digging an in-ground garden and Arizona tends to have very basic soils. I’m feeling pretty confident in my results since I don’t have any caliche in my yard (at least everywhere I’ve dug in the last year).

 

[DirtMechanic]

Did you use tap water or distilled? I ran that same test and mine showed high even though its 5-5.5 pH. The tap should fluctuate around 7 and the distilled water 6

 

[DrMike27]

I just used bottled water. Even if my result was artificially high, I’m feeling pretty good about it.

 

[DirtMechanic]

Trust, but Verify.

 

[DirtMechanic]

So based on your complete trust (wink) in the test, what guidance have you decided to follow? I personally failed with every test utilizing water, and I am sure it was a mass thing. I had no backup detail from the vendors for followup of any sort.

 

[DrMike27]

I decided to do the ‘trust, but verify’ approach and tested the area at two different places at two different depths and got the same results. I’ve seen reviews saying that the test could be flawed, so what I then did to kinda give me a little more insurance was till about 12-18” and then mix in a few yards of a potting mix and mix everything together. So far, I have only transplanted my pomegranates but I’m planning on using the plot for beets and sweet potatoes.

 

[DirtMechanic]

What I found out about the tests that use water is that they are great for water and pools. I suspect the mass and buffering capacity of water is taking over the test when its a smaller amount of drier soil getting measured. I dont think the chemicals are magically sensitive, and if the test was full of dirt (irony!) instead of water you could not see the color. One way to back check is soil survey mapping. UC Davis has one. The Link Here. I just enter the street address. Anyway, soil will be made up of several sub types, an upper oxidizing layer is often listed as a small percentage with the deeper soil indicated by larger percentages. The pH will drift toward those lower soils and be somewhere between the upper top soil pH and the deeper core soils pH. But people building will bring in trucks of soil from offsite and other things so I like a stick meter just to check. AZ soils are supposed to be alkaline as I recall. Your grass certainly looks happy.