Mulch is a layer of material applied to the soil surface, serving both an aesthetic function and a practical purpose in the garden. Organic mulch primarily helps regulate soil temperature, slow water evaporation, and suppress unwanted plant growth. Choosing between natural wood mulches, such as cedar and cypress, requires understanding their distinct characteristics. This comparison examines the features of cedar and cypress mulch to help determine which product is best for specific gardening goals.
Material Structure and Longevity
Cedar mulch is derived from the bark and wood of cedar trees, typically Eastern Red Cedar or Western Red Cedar, resulting in a distinct, reddish-brown color and a strong aroma. Natural compounds in the wood make it highly resistant to decay, allowing it to maintain its structure for three to five years. Because of this slow decomposition, cedar adds fewer nutrients back into the soil compared to faster-breaking mulches, and it can temporarily tie up soil nitrogen as it breaks down.
Cypress mulch is generally an orange or golden-brown color, made from the bark and softer wood of the cypress tree. It is also naturally resistant to rot, though its lifespan is often slightly shorter than cedar, lasting approximately two to three years before needing replenishment. When shredded, cypress mulch has a fibrous, interlocking quality that helps it stay in place and resist being washed away by heavy rain. However, this shredded material can sometimes compact into a dense layer over time, potentially hindering the movement of air and water into the soil below.
Performance Metrics: Water Retention and Weed Suppression
Both cedar and cypress mulches manage moisture and control weeds, though their physical forms influence performance. Cypress mulch is often promoted for its ability to retain soil moisture, which is beneficial in hot or arid climates. However, if applied too thickly, the dense, matted structure of shredded cypress can compact so tightly that it repels water, forming a crust that prevents moisture from reaching plant roots.
Cedar mulch also retains water well, reducing evaporation and helping maintain a cooler, stable soil temperature. Both mulches create an effective physical barrier against weed growth by blocking sunlight, which is necessary for germination. Their dense, interlocking nature helps them create a uniform cover that smothers existing weeds and prevents new ones from taking root.
Specific Factors: Pest Resistance and Environmental Sourcing
A notable distinction between the two is their inherent pest resistance, which stems from chemical compounds within the wood itself. Cedar wood contains aromatic oils recognized for their natural insect-repellent properties. These compounds help deter common garden pests such as termites, ants, cockroaches, and certain beetles, making cedar a strong choice for pest-prone areas. A potential drawback is that these same oils may also discourage beneficial insects like ladybugs and lacewings from inhabiting the mulched area.
The pest-resistant reputation of cypress is less reliable today, as much of the mulch is sourced from younger trees that lack the decay-resistant heartwood found in older specimens. Some modern cypress mulch has even been noted to attract termites, contradicting its traditional reputation. Beyond pest concerns, the environmental sourcing of cypress mulch is a significant issue. It is often harvested from slow-growing Baldcypress and Pond Cypress trees in sensitive wetland ecosystems of the Southeastern United States. This practice contributes to habitat loss and the degradation of natural water filtration systems. Cedar mulch, by contrast, is generally considered a more sustainable option because it is often made from the byproducts of existing timber operations or from more rapidly renewable species.
Selecting the Right Mulch for Your Garden Needs
The choice between cedar and cypress mulch ultimately depends on balancing garden priorities, performance, and ethical concerns. If long-term appearance, natural pest deterrence, and environmental sustainability are the primary goals, cedar mulch is often the preferred selection. Its longer decomposition time and proven repellent qualities against specific pests offer a low-maintenance and eco-conscious solution.
Conversely, cypress mulch may be the better option in certain situations where maximum moisture retention in a hot, dry climate is the focus. However, those choosing cypress must be aware of the risk of compaction and the potential environmental impact associated with its sourcing from ecologically sensitive wetlands. For many gardeners, the balance of longevity, pest-repellency, and sustainable sourcing makes cedar the more versatile choice.