I suggest that folks start by looking at their town's Annual Water Quality Report.
Here's your latest one.
The pH is slightly acidic, so it seems likely you don't have an excess of calcium or magnesium, so even if you don't want to spend the money on a
water analysis, I think you can safely add more to be sure the plants are getting enough.
There are a couple of ways you can go. Personally, I prefer to use a fertilizer that contains calcium and magnesium so I don't have to bother with another product. I prefer
K-Lite fertilizer, but the
MSU RO formula is also good.
Another alternative is to get a
cal/mag supplement and add it to your irrigation regimen periodically.
A third option is incorporating gypsum or dolomite in the potting medium or top-dressing with a little for both calcium and magnesium, or pulverized, calcined oyster shell (often sold for poultry) for just calcium.
When I moved to coastal NC, with a similar geology to yours, I got a water sample and found that my water contains almost no magnesium, but that lime is added to stabilize the pH, so there's plenty of calcium. I could have just used Epsom Salts for the Mg, but again, I find it easier to just use a complete fertilizer.