The Disadvantages of Wood Shavings as Mulch

Compaction

• To be of the most value in a landscape, mulch needs must be dense enough to discourage weeds and cool the soil, and porous enough to allow air and moisture to move through it freely. Very fine mulch, like sawdust and small wood shavings, compacts easily and creates an impenetrable barrier to water and air. Use only wood shavings that are large and irregularly shaped. If you can squeeze a moist handful into a dense lump, the wood shavings are too fine to be a satisfactory mulch. If your wood shavings mulch develops a crust on top, use a hand cultivator to break up the crust and loosen the mulch.

Movement

• Mulch must stay in place despite strong winds. Wood shavings have moderately good wind resistance. If your landscape is very exposed, however, or if high winds are common in your area, use wood shavings only in sheltered beds. Use shredded bark, bark chunks, large wood chips or an inorganic mulch in wind-exposed areas. Also avoid using wood shavings as mulch in areas prone to flooding — such as near a downspout — since the lightweight shavings are easily swept away by moving water.

Fire Hazard

• Unlike large-particle mulches such as shredded and chunk bark, wood shavings create a fire hazard when dry, so never use them close to your home or other structures. Avoid their use near any place where they can be ignited by sparks or hot exhaust, such as a driveway or a barbecue.

Rapid Decomposition

• Because wood shavings are small, they decompose rapidly when in contact with the soil. Wood shavings mulch must be topped off at least every year and more often in areas with plentiful rainfall, since moisture encourages rapid decomposition.

Nitrogen Depletion

• Wood shavings' rapid decomposition can cause a nitrogen deficiency in the soil, since soil organisms tie up nitrogen as they digest wood particles. Ohio State University Extension recommends applying 1 to 2 pounds of nitrogen per 1,000 square feet of mulched area as a precaution. Ask your garden center's advice on how much fertilizer you must use to supply an adequate amount, as the nitrogen content of fertilizer products varies. Never incorporate mulch into the soil when replanting an area; move the mulch aside to lessen the chance of nitrogen depletion.