Acid-loving plants thrive in soils with a pH level lower than 7, ferrous sulfate. Acid-loving plants may react to high pH soils with yellow leaves and stunted growth. Acid-loving plants include azalea, camellia, crape myrtle, holly, blueberry and hydrangea.
One substance that may be used to nourish acid-loving plants is elemental sulfur. According to Michigan State University, elemental sulfur is very slow acting, and therefore should be added to the soil 6 inches deep one year before planting an acid-loving plant. Elemental sulfur should be used when planting an acid-loving plant in sandy, loamy, or clay-rich soils, which tend to be very alkaline.
A simple way to feed acid-loving plants: add used coffee grounds to their soil. Coffee grounds contain the low pH levels that acid-loving plants crave. Cooper points out that this practice not only nurtures acid-loving plants, but reduces kitchen waste.
Another soil additive that benefits acid-loving plants is ferrous sulfate, also known as ferrous sulfate. According to Drugs.com, ferrous sulfate is used in nutrition to combat ferrous-deficiency in the blood. Michigan State University reports that ferrous sulphate works more quickly than elemental sulfur, typically showing results in plants within three to four weeks of application. It is not recommended to apply more than 9 pounds of ferrous sulfate per every 100 square feet of soil.