I've planted Japanese maples in mix very similar to the 5-1-1, and I've never had an issue.
Add the recommended dose of Garden Lime - 1 tablespoon per gallon of mix - and simply add white vinegar
to your watering solution periodically. It's far easier to adjust the pH of your water than it is to try and maintain
a specific soil pH (which is constantly changing, depending on temps, moisture levels, fertility levels, et cetera).

Josh

About how much vinegar and how often? Every time I water/ fertilize with weak FP? My water is a perfect 7. What does the lime do besides make the mix more alkaline? This is probably a loaded question huh :)?
thanks Josh,
Julie

In addition to slightly raising pH, the Lime is a source of Calcium, primarily.

Short answer, add a capful of white vinegar to a gallon of water as often as you think of it.

Long answer, take a gallon of water, add vinegar until your pH is between 5.0 - 5.8,
take note of that amount of vinegar, and then add the same amount to a gallon of water
whenever you water/fertigate.

Josh

thanks Josh!