How Do I Keep Mushrooms from Growing In My Mulch?

Pine needles or pine straw mulch do not encourage mushroom growth.

“I buy fairly expensive mulch each year but continually experience mushrooms growing in it.  What causes this and is there anything, (non-toxic), I can use on the mulch to stop mushrooms from growing?” Question from Diane of Newark, Ohio

Answer: Traditional bark mulch is the perfect medium for mushroom growth, especially if it’s kept moist. The job of mushrooms and toadstools is to break down forest detritus, such as old trees, bark, and leaves. The main thing that you can do to stop mushrooms from growing in your mulch is to switch to a different type of mulch that does not encourage mushroom growth.

Organic Mushroom-Free Mulch Options

Mulches that are more acid are less apt to discourage mushroom growth. Two of the easiest to find and most reliable are pine straw or pine needles and pine bark nuggets. Pine straw is purchased in bales and makes a very attractive garden mulch. Pine bark chunks are a reddish color and slow to break down. Another organic option would be the application of screened compost, which is finer and breaks down more quickly.

Stone mulches are another option. Please click here to read a full article about all types of mulches and garden top dressings.

Happy Gardening,


This bed is covered with a thick layer of pine straw,


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

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