Ann:

Rather than focus on the Ph meter, which you may never be able to fine-tune to your satisfaction, why don't you tell us where you are located so we have some idea of what your native soil might be like, and exactly what you are using to amend your soil. Meanwhile, you can clean the probe of your Ph meter with the rough side of a kitchen sponge, which may or may not make the meter work to your satisfaction, but will remove any surface corrosion without damage to the instrument.

First let's clear up the matter of trying to raise the Ph around hydrangeas, which was a mistake if you really did it. This plant takes the same low PH conditions as blueberries and rhododendrems. Did you apply lime around these plants, or what?

The usual way to lower the Ph when planting the species in question is by mixing in lots of peat moss with the native soil. Addition of garden sulfur is helpful as a long-term acidifier in soils with a naturally high Ph. After that, you can make surface applications of iron sulfate, aluminum sulfate, or products like ironite or Hollytone, which is both a conditioner and acidifier. Soils with a high organic content tend to maintain a naturally lower Ph, so the use of compost at planting and as a mulch is a good technique.

So tell us what you used, and when and how you used it, and someone will give you a readout of whether what you did was helpful or not. And don't forget to tell us where you are.

Don Yellman, Great Falls, VA

You need to scrub the end with the little white pad that came with the meter. Scrub vigorously. If you lost the white pad get one of those scotch brand green dish scrubbie things and use that. I clean mine before every reading and it has remained accurate for five years.

Scott

OK, I scared myself there---I have been acidifying for blueberries, rhodies, and hydrangeas. Hydrangeas in acidic soil tend to have bluer flowers---that's why I was acidifying for those too.

I live in Anne Arundel county, Maryland. My soil is mostly sandy and quite nice, but there are pockets of clay. No matter what I plant, I ammend heavily with compost---mostly leaf grow, but also some old manure and when available, home made compost. When planting each of the plants I mentioned, I mixed generous amounts of aluminum sulfate into the soil.

The rhododendrons are doing OK...I also fertilize those in the spring with Holly Tone.

My hydrangeas haven't bloomed yet, so I don't know how that'll turn out.

My concern is the blueberries. Although they bloomed profusely this year and it looks like I'll get a few handfuls of berries, the plants look stunted to me. They've been there 3 years and have barely grown at all. I just don't know what to do for them any more. That's why I was checking the pH.

I'll try cleaning the probe. I also read somewhere not to use it to test liquids (I wonder why?!?) so that may have been part of the problem with my test.

Ann

Ann:

A Ph too high for blueberries usually is expressed in poor health of the leaves -- yellowing, green veining etc. -- rather than slow growth alone. Perhaps your blueberries could use a shot of nitrogen for faster growth, and the Hollytone could help there, but pure ammonium sulfate might be better if you can find it at a nursery. Sandy soils tend to lose their nitrogen a little faster than clay soils, although it sounds as if you are doing the best you can with your compost program.

I deep mulch my blueberries with stable manure every winter, and that seems to have eliminated the need for any other amendments.

Don Yellman, Great Falls, VA

Why ammonium sulfate if you think nitrogen is the problem? I think the leaves are OK...maybe just some Hollytone?

I need to get my hands on more manure. I need a truck! : )

Thanks Jellyman. Your name alone is inspirational.

Ann