Coffee Grounds for Acid-Loving Plants: Compost, Not Direct Application

A gardener recalls being told coffee grounds aren't good for acid-loving shrubs (azaleas) but forgot why. Friend disagrees.

The Nuance

Coffee grounds are excellent in compost (nitrogen source, ~2% N). They break down to near-neutral pH.

Why Not Direct on Azaleas?

• Fresh grounds can form a water-repellent crust.
• Caffeine may inhibit some plants.
• Azaleas hate anything piled against their crown/trunk (rot, pests).
• pH effect is minimal and temporary.

Best Use

Add to compost pile with leaves, grass clippings, vegetable scraps, eggshells. Use finished compost as mulch/soil amendment. Or mix grounds with potting soil first, then apply as thin top dressing away from stem. Water well.

For Acidification

Use elemental sulfur, aluminum sulfate, or acidifying fertilizers (Miracid) for reliable pH drop.