I am assuming this is eastern PA? It doesn't sound that unusual for the rest of the state. It is quite high for the east, and likely to raise a few eyebrows among those who haven't hit it before. My native pH is 7.2, and I have been accused multiple times of sleep-liming.

It isn't a concern *unless* you are trying to grow plants that are sensitive to higher pH like azaleas. Somewhere, which I wish I could remember where, I read that the real problem these plants have is that they have become extremely efficient at pulling minerals out of acidic soils where they are largely tied up. So when they are planted in higher pH soils they pull out too much mineral, and suffer from a plant form of arteriosclerosis

Apparently aluminum toxicity is only a problem at low pH. The aluminum reacts to become a toxic form.

Yes it is eastern PA.

After talking to the PA extension agent , this area is common for high calcium levels and many soil reports come back the same. I am ok with the 6.6 pH. In the future if the homeowner want to lowers the pH, I think that iron sulfate or garden sulfur would be a good choice, rather than the aluminum sulfate. I could not find a test at PS for aluminum sulfate, so I am thinking about recommending that they wait till fall to plant, and that adding compost to the soil may not be a bad idea. Thanks for your help - mad g.

pH chart

Forget about altering the soil, instead plant species adapted to calcareous soils ie:

eastern red cedar or selections thereof

many oaks including dwarf chinquapin oak (shrub)

sumacs & smoketrees

hop hornbeam

NJ tea - must be sunny and well-drained

sassafras

spicebush

many viburnums

most legumes including redbud

meadow-sweet Spiraea latifolia (best in wet areas)

I don't think that adding compost is EVER a bad idea.

And I have to agree with Ken here- fighting mother nature is a full time job and the moment this homeowner relaxes the soil will bounce right back to it's natural state. She always wins over the long term.

If I was this homeowner I'd spend my time researching plants that will do well in these conditions rather than trying to find methods to fight it.

calcareous soils - thanks I was looking for that term. Are you aware of any plants that do not tolerate high calcium levels. I believe that there may be many plants that not be bothered by this high level --- Driving around the same neighborhood I see lots of thriving plants. However I will certainly look for the list of plants that do well in calcareous soils ( it is an important list to have! for this job)

This is a front yard in a residential neighborhood. I need lower plants that work in a front bed.

This is the first time the homeowner did a PSU soil test. Each time they did a store bought self test which only told them pH. I typically suggest this test because I do not want to select plants for the design that will not do well.

Altering the soil - IMHO when large old shrubs are removed from a bed it is a good idea to try to amend the depleted soil. My other concern was if there is any level of aluminum sulfate that the composted soil may help. It cant hurt, and it can be easily add to the bed which has no shrubs now.

Thanks for all the good advise.

In my part of the world there are abundant calcareous soils. After ploughing many field are essentially white. But is excellent farmland and we can grow a wide variety of plants. Beech woods for example are at home here.

Azaleas, rhododendrons, blueberries and most heathers are not suited to these soils. Camellias and some magnolias struggle. Mountain Laurel is impossible.

Here's a link, but it is for the UK so some suggestions might not suit your climate.

Previous comments about working with the soil you have rather than trying to amend to alter pH make excellent sense!! You can make some small adjustments but attempting a larger change will be just an exercise in frustration. Most soils have a buffering capacity that resists any permanent significant pH change.

And you want to avoid using aluminum sulfate to acidify soils if you are growing any ericaceous plants. They are especially sensitive to aluminum toxicity, which will be a real concern with multiple applications of this product.

floral - the client said they could not grow Azaleas, rhododendrons! Thanks for the excellent list. I have seen some of this plants growing on this property. gardengal, - thanks for the ericaceous recommendation --- I will avoid.

I don't think that adding compost is EVER a bad idea

As long as it is clean (not contaminated with herbicides for instance) and put on top of the ground, as mulch, when being used for long term plants like shrubs. Digging it in is appropriate only for subjects like annual vegetables and flowering annuals, that have small root systems and are planted in beds that are re-worked frequently.