Don’t Just Pile It On: Why Old Mulch Needs To Go

 

 

Mulch makes beds look clean and helps plants thrive but leaving old, decomposed mulch in place and piling new mulch on top can quietly damage your plants over time.

 
 

Old Mulch Turns Into Soil

 

As mulch breaks down, it stops acting like mulch and starts acting like soil. Layering new mulch over old causes stacked layers to create a dense, soggy buildup that:
 

• traps excess moisture
 

• encourages fungus
 

• slows evaporation
 

• blocks oxygen from the roots
 

 
 

Removing Old Mulch Keeps Beds Healthy

 

Clearing out the decomposed layer helps you:
 

• maintain proper soil depth
 

• improve airflow
 

• reduce pests and disease
 

• ensure new mulch works as intended
 

• prevent long-term decline in shrubs and perennials

 

Even removing 1–2 inches makes a noticeable difference.

 

 
 

How Often to Do It

 

• Remove decomposed mulch each time you add more
 

• Remove ½ of the amount you add. (Ex. Remove 1 inch if adding 2 inches of mulch)
 

• Maintain a total mulch depth of 2–3 inches
 

 

A Small Step With Big Benefits

 

Taking the time to remove old mulch before adding new keeps your landscape healthier, prevents hidden damage, and helps your plants stay vibrant year after year.