Can I Use Black-Dyed Cedar Mulch on Grape Vines?

Regular Cedar

• The aromatic oils in cedar repel insects. This can be good when it comes to harmful insects, but cedar oil also repels beneficial insects, which can be a problem when it comes to bees that are needed to pollinate the grapes. Because cedar mulch doesn’t decompose quickly, it doesn’t need to be replaced as often as mulches such as hay, resulting in less time spent working. As it decomposes, cedar mulch adds a small amount of nitrogen to the soil, which is perfect for growing grapes. In addition, regular cedar mulch costs about 30 to 40 percent less than mulch that is dyed black.

Black Cedar

• Regular cedar mulch turns gray after a few months in the sun. Colored mulches retain their color longer, sometimes even into the next year, thereby looking more attractive. Organic mulches aren’t usually a good choice for grapes because they can cool the soil down too much. Many grape growers use black plastic mulch to control weeds and keep the soil warm. Black-dyed cedar mulch warms the soil in a similar way to black plastic.

Disadvantages

• The dye in fresh mulch can rub off on hands and clothes and may stain the driveway or sidewalk. Many companies won’t deliver it if rain is forecast, and they suggest working with it only on dry days. Once the mulch is spread out, the dye “sets” and doesn’t usually cause further problems. The dye used to make black cedar mulch comes from carbon black, which typically is sourced from a petroleum product. Carbon black also can come from a vegetable source. Check the source of the pigment with the manufacturer, if this is a concern. Horticulturist Holly Scoggins at Washington State University says that certain colors can affect plant growth. However, little is known about the effects of dyed wood mulch on growing plants.

Proper Mulching

• Because mulching helps retain soil moisture, make sure not to mulch poorly drained soil; grapes don’t like it. Don’t pile mulch around young plants. Instead, leave a few inches around each plant to ensure that it receives enough air and sun. When mulching, either cover the entire ground or limit the mulch to a 4- or 5-foot band beneath the trellis. Apply a nitrogen fertilizer before adding mulch. Lay down 3 or 4 inches of native mulch before applying a thin layer of black-dyed mulch, approximately 1 inch deep. This will give the grapes the advantages of natural mulch along with the aesthetic look of using mulch that’s dyed black.