Choosing the best type of colored mulch may largely depend on your reasons for using it. Some people use colored mulches to create an appealing contrast to their plant, thereby making them more noticeable. There are also people who use colored mulch because they believe it enhances the growth of specific plants. Mulches that have been dyed black are also occasionally purchased because they tend to help the soil retain heat from the sun in addition to making some plants stand out. Choosing the best colored mulch to enhance the appearance of your garden or help with its growth depends on the color and type of plants you have.
If you want to make light green plants stand out, you may benefit from using a red mulch. Red mulches also tend to be a popular choice to use around rock gardens. You can use a brown mulch to enhance the appearance of almost any plant because it may complement all shades of green. Blacks can also provide a good color backdrop to make any plant stand out, but it is typically used for heat retention purposes rather than for its appearance.
A mulch that has been dyed black may be an ideal choice for plants that are in very shady locations because the dark color will help the soil hold in the heat from the light it does receive. It may not be a good idea to use black mulch around plants that get lots of sun, because the excess heat could damage them. Some evidence from various studies suggests that red mulch might help like-colored plants, such as tomatoes and strawberries, grow to be larger and healthier. This would likely be due to the similar color of the mulch reflecting the heat from the sun to the plants and encouraging growth.
Colored mulch is usually made of either plastic, rubber, or wood, which may be important to take into consideration before purchasing. Plastic might not be the best choice if you want something that will decompose over time, nor would rubber. Wood is a natural substance, but it could contain pieces of recycled pressure-treated wood. Before 2003, pressure-treated wood contained arsenic, and there is a chance that parts of old pressure-treated wood may be in colored mulch. To possibly eliminate your risk of getting trace amounts of arsenic in your garden, you can look for colored mulches that have the MSC (Mulch and Soil Council) certification logo, which means it should not contain any arsenic-contaminated wood.