A heavy mulch is least desirable for which plant?

A heavy mulch is least desirable for which plant?

• A. Fern
• B. Rose
• C. Maple
• D. Iris

Answer: (D)

Mulch depth should match how a plant’s roots and crown sit in the soil. Iris have rhizomes that lie near the soil surface, so a thick layer of mulch can cover and smother them, trap moisture and heat around the crown, reduce air exchange, and promote rot and disease. Keeping mulch light and away from the crown helps the iris stay healthy. Ferns and roses tolerate or even benefit from a moderate mulch as they have deeper roots or more forgiving crowns, and maples handle mulch as long as you don’t pile it against the trunk. The iris is the one for which heavy mulch is most likely to cause problems.

Mulch depth should match how a plant’s roots and crown sit in the soil. Iris have rhizomes that lie near the soil surface, so a thick layer of mulch can cover and smother them, trap moisture and heat around the crown, reduce air exchange, and promote rot and disease. Keeping mulch light and away from the crown helps the iris stay healthy. Ferns and roses tolerate or even benefit from a moderate mulch as they have deeper roots or more forgiving crowns, and maples handle mulch as long as you don’t pile it against the trunk. The iris is the one for which heavy mulch is most likely to cause problems.