Mulching tips for the landscaper

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.  

Several of our Extension educators report getting a number of calls and questions regarding landscape mulch; How much? What’s the best mulch? And so on.

Over the past few years we’ve conducted a trial on several mulch types in replicated mini-landscapes at the MSU Horticulture Teaching and Research Center. The mulches we used were ground pine bark, hardwood bark, cypress mulch and ground pallets (the ubiquitous red mulch). We also included two treatments without mulch; either with or without weed control. The take-home message from the research is the properly applied mulch consistently improves soil moisture availability, weed control and plant growth compared to plots without mulch, even if the plots were kept weed free. Most of the mulches worked equally well. Plants in the cypress bark plots grew a little slower and had lower rates of photosynthesis than the other mulches, but were still ahead of the mulch-free plots. So the final decision on the choice of mulch for most homeowners and landscapers will come down to a matter of cost and aesthetics. (view photos)

The advantages of organic mulches (improved soil properties, ease of application) usually outweigh the advantages of inorganic mulches such as river rock or white rock.

Two to three inches of mulch is adequate – more is not better.

Don’t pile mulch around the base of trees (the dreaded mulch volcano) – keep a 6-inch mulch-free ring around trees.

Don’t use uncomposted grass clippings or leaves as mulch – they will form a thick, smelly, unsightly mat that inhibits moisture and oxygen movement to plant roots.

Note: Thanks to Kalamazoo Landscape Supply for donating the mulches for the project.

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