Acidifier

An acidifier is any soil amendment that decreases the soil's pH. This would include:

Substances That Increase Soil Acidity

Sawdust
Peat moss
Sulphur
Wood chips
Cottonseed meal
Leaf mold
Coffee grounds (Be sure to compost them first.)

Herbs and Plants That Love Acidic Soil

Sorrel (French), blueberry, honeysuckle and dandelion

This is a glossary entry that will help you understand some of my blogs better. Plants have a vocabulary; most specialized areas of learning do. Pick up one new term a day, and in no time you'll be a pro.