Sorry for the couple-week late response, but I just bought one and it seems to reflect what I expect at least. I'm not sure how these meters work, but mine only seems to report anything useful if it's held in soil. If I hold it directly in water or any other liquid, it doesn't do anything. But, I took some soil from my garden, which is slightly alkaline (according to both it and a traditional kit), poured some lime juice on the soil, and the pH meter immediately lowered its reading. Might not be accurate, but I'm going with it for now. Mine was $8 at home depot, brand is Hold All. If anyone has any ideas on how to test it in soil with a pre-known pH, I'll try that and see if it matches.

Here is a comment from the website Journal of Extension joe.org:"A soil probe that was inserted into moist soil in plots provided poor response to soil pH and is not suitable for diagnosis of soil pH problems." Suggest a reading. Also suggest contacting your local county extension agent for advice. Here is a link that might be useful: Journal of Extension

The only tree I have on my urban lot is what I thought was a Norway maple. It takes up an entire corner of my yard, so pretty much a quarter of my property. It took a while to do the entire area, but I have a pathway walking straight towards the trunk that then splits into two paths, one going off to the side where I have a deck and the other simply circles the tree and joins the other path. I have lamium, hay scented ferns, blue columbines, corydalis lutea, fringed bleeding hearts, and a couple hosta growing right at the base of the tree and then under the rest of the canopy to either side of the path I have more of the same, plus brunnera, 5 or 6 other ferns, epimediums, European ginger, creeping forest type phloxes, dozens of hosta varieties, Solomon's Seal, Jacob's ladder, lungwort, sweet woodruff, Lady's mantle, and toad lillies. I do have to water during dry spells and in some areas the plants barely flower, if at all, but they're green and growing and better than clay, rocks, and weeds, which is what was there when I started. I keep a thick layer of cedar mulch around everything but I plan on switching to shredded leaves for mulch once I get a shredder. I do realize you can't heap soil and mulch ontop of tree roots without killing the tree so I didn't go crazy, but the couple inches of mulch I have down has been there for 5-6 years now and the tree is fine. In some areas I dug the ground over, but in others I was lucky I could hack a hole in the cement-like clay and masses of roots big enough to shoehorn the plant in. In that area I stuck with cast iron plants like the hay scented ferns and basic hostas like lancifolia - nothing fussy. I figured what lives lives and I'll worry about replacing what dies. Nothing's died yet! Lisa

Ok well then I will add some vinegar to the water before watering it. Btw what soil pH tester do you guys use? I bought one from lowes for 10$ and tried it today and it was crap. The pH showed 6 or 7 for every soil I tested on. That is, the 5-2-1 mix that I just made today, my conifer pots in 5-1-1 mix, and regular ground soil.