When Not to Use Cedar Mulch
According to Fine Gardening’s Patrick Kelsey, mulch is “any organic substance used as a top cover to soil that enhances the rooting environment of plants.” This garden multitasker addresses issues related to water retention, temperature control, and other potential problems. Cedar mulch also adds a rich color and aroma to the garden. Most experts agree that it is a preferred option. At times, however, it might not be the best choice.
Some people may be sensitive to the cedar fragrance, and they may find that it exacerbates allergy symptoms. This is especially true when the chips are used in flower beds close to entrances and windows. Overcome this barrier by saving the cedar mulch for trees and plants that are farther from areas in which susceptible people may gather or spend significant time.
When woody plants decompose, they can draw nitrogen from the soil, depleting the levels needed by other plants to thrive. Generally, this is only a problem when the products are tilled into the soil. For this reason, avoid using cedar chips on beds containing annuals or in vegetable gardens, where it will be incorporated into the soil layers, and save it for plantings where it can remain on the soil surface. If you do choose to mix it, amend the soil with extra nitrogen to balance the depletion.
When fresh, wood mulches can add acid to the soil. While it is usually a minimal amount, if the soil already has a low pH level, using cedar mulch could create a problem. If you still want to use the product, allow it to compost for a year or two or add lime or wood ash to your beds before planting and mulching. This is not usually a problem when the cedar only rests above the ground.
One of the reasons for using mulch is to help the soil retain moisture. If the area has low or wet spots, a thick layer of cedar mulch can cause too much water to stay in the soil, causing root rot and other problems. Either avoid the use of mulch in those areas or use a thinner layer there.
There is some argument that cedar mulches are toxic to very young plants and seedlings. However, most experts agree that this is only a problem when you use cedar sawdust or when plants have very shallow root systems. Switching to larger wood chips should solve the problem.
One advantage of using cedar to mulch plants is that most insects avoid it, unlike some other wood chips that attract termites and other pests. But it could discourage beneficial as well. If you want to keep beneficial insects in your garden, you might want to use other organic mulches,