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MULCHING YOUR TREES

Mulching is one of the easiest ways to help young trees become established and grow. Mulch can be any soil covering used for weed control, moisture retention, and similar purposes, and can be a tree=s best friend if used properly. Mulch can benefit larger trees, also.

Mulches can be either organic or inorganic. Organic mulches include bark (shredded or nuggets), wood chips, composted leaves and yard waste, pine needles, straw, grass clippings, and shredded newspaper. Composted leaves and grass clippings tend to decompose more rapidly than bark mulches. Inorganic mulches include stone materials such as decorative gravel and crushed lava.

Benefits of mulching your trees include keeping moisture in the ground to prevent the soil from drying out by reducing evaporation, preventing grass and weeds from growing around the tree and thereby keeping lawnmowers and string trimmers away from the stem (prevents lawnmower blight), preventing soil erosion and compaction, improving the aesthetic appearance of the tree site, and moderating the soil temperature to protect roots. Water and nutrients are transported up and down a tree stem just inside the bark, so any bark damage by equipment can kill a tree. Organic mulches also return nutrients to the soil as the mulch breaks down and improve the soil.

Apply mulch to a young tree immediately after planting, and then add sufficient mulch periodically thereafter to maintain an adequate layer. Use enough mulch to cover the rooting area of young trees. Spread mulch in a circle with a 2 to 3 foot radius around the tree, and 2 to 4 inches deep. The mulch should not touch the stem of the tree, but rather be kept several inches away. The resulting mulched area should resemble a doughnut, with the tree stem growing through the doughnut hole. Piling too much mulch around the base of a tree has absolutely no benefit, is a waste of time and money, and can be harmful to the tree. The resulting mountain of mulch only encourages root growth into the mulch, causes damage to the stem, inhibits air exchange, and encourages rodent and insect damage. A mulch bed more than 4 inches deep is not necessary.

Over time, organic mulches can become compacted, and should be loosened with a rake periodically. Add fresh mulch as the existing mulch decomposes to maintain a 2 to 4 inch layer. Hardwood bark mulches have usually been aged or composted, and can be dyed in various colors. Wood chips that are very fresh may cause a temporary nitrogen deficiency as the decomposition process begins, but will actually add nutrients in the long-term. Some nitrogen fertilizer might have to be added if large amounts of fresh chips are used.

Sources of mulch can vary, including a local garden center, tree trimming companies, and local landfills. Yard waste, and also Christmas trees, are sometimes composted or chipped at landfills and become available as mulch for local residents. Mulch is available for Baltimore County residents at the Eastern Sanitary Landfill off Pulaski Highway in White Marsh. Call 410-887-2000 for more information. Organizations conducting community plantings in Baltimore City can call the City=s Forestry Division at 410-396-6108 for assistance with obtaining mulch.

       The Forest Conservancy District Board for Baltimore County

9405 Old Harford Road

Baltimore, Maryland 21234

(410) 665-5820 

Email Robert Prenger ....... rprenger@dnr.state.md.us

 Melvin Noland ....... mlnoland@bcpl.net