Mulch is a beneficial landscaping material, but its quality degrades quickly if not stored correctly. Proper storage preserves the material’s texture, color, and effectiveness, preventing waste and ensuring the organic components remain ready to enrich your soil and protect your plants. Understanding the specific needs of different mulch types is key to successful preservation.
Before You Store Your Mulch
Mulch comes in two main forms: bulk piles or sealed bags, and preparation steps differ for each. Bulk mulch must be assessed for moisture content before storage. It should be slightly moist, but never saturated, as excessive water promotes anaerobic bacteria growth, leading to a foul, sour smell. If you detect a strong odor, spread the mulch in a thin layer and aerate it for several days to allow toxic organic acids to dissipate before piling it up again.
The type of material dictates the preparation needed for storage. Organic mulches, such as wood chips and straw, naturally break down over time. Inorganic mulches, like rubber or stone, do not decompose and require less maintenance, needing only protection from debris. Bagged organic mulch should be checked for ventilation holes; if none are present, poke a few tiny holes to allow the material to breathe and prevent mold formation.
Choosing the Right Storage Location
The storage location is the most important factor in preserving mulch quality. The ideal spot is dry, shaded, and offers good ventilation to manage moisture and decomposition byproducts. A covered area like a shed, garage, or patio is an excellent choice for both bagged and bulk material. This protects the mulch from rain, which introduces excess moisture, and direct sunlight, which can fade the color of dyed mulches.
Keep all mulch materials elevated off bare ground or concrete floors. Moisture from the earth or condensation can seep into the bottom layers of bulk piles or bagged material. Placing mulch on a wooden pallet, cinder blocks, or a durable tarp prevents this and promotes airflow beneath the material. When storing bulk organic material outdoors, never choose a low-lying spot where water can collect, as this encourages detrimental anaerobic decomposition.
Maintaining Mulch Quality During Storage
Active maintenance is necessary to prevent degradation, especially for bulk organic mulch stored for extended periods. Large piles of wood-based material face the risk of spontaneous combustion, caused by heat generated from microbial decomposition. If the internal temperature of a compacted pile rises above 155–185 °F, it can reach an ignition point.
To mitigate combustion risk, bulk piles should be turned or aerated every few weeks to release trapped heat and introduce fresh oxygen. Regular turning also prevents caking and slows the decomposition process. Bagged mulch should be stacked neatly, allowing space between layers for air circulation. If containing bulk mulch with a heavy-duty tarp, drape it loosely over the top and never seal it tightly, as ventilation must be maintained.
Periodically check the stored material for signs of pest infestation or mold, which often appears as white, thread-like strands called mycelia. Most organic mulches can be stored successfully for several months, while inorganic materials last indefinitely if kept clean and dry.