Last week, I posted some pictures on Facebook of healthy, blooming, summer perennials. My friend, Betty, who lives in coastal South Carolina, remarked, “What’s in your soil? Wow!”

I responded that our soil is acidic, especially in the sandy areas around the house, with some heavy clay in the field. Amending the poor soil is an ongoing task. We add compost to the front garden beds and borders and to the raised vegetable beds every year. In the past few years, Jim has mixed mushroom compost from a local supplier with garden soil, and we have had good results.

Betty’s second question was, “Is mushroom compost better than peat moss?” Her question is one I have heard several times about compost, in general. Both products are used to amend poor soil, but they are derived from different sources and have different functions as soil additives.

Peat moss is composed of dried sphagnum and other mosses. It is harvested or “mined” from peat bogs that have formed over thousands of years. I...