Cedar is generally better for mulch: Cedar Mulch: Aromatic: Cedar mulch has a pleasant, natural aroma that can help deter certain pests, like moths and ants. Decay Resistance: Cedar mulch decomposes relatively slowly, meaning it will last longer in your garden. Cypress Mulch: Decay Resistance: Cypress mulch also decomposes slowly and lasts a long time. Moisture Retention: It can help retain moisture in the soil.