Is colored mulch safe for your gardens?
Colored mulch has always made me nervous, even before you started to hear stories about soil contamination and how it wasn't good to use it around food crops. Since the colors were so unnatural looking, I never found them appealing in my landscape. In fact, black mulch is a huge pet peeve of mine. I don't mean to insult anyone who enjoys that look, it's just not for me.
Is colored mulch safe? I think the jury is still out. When colored mulches were first introduced, the dyes contained heavy metals and other undesirable chemicals that would eventually seep into the soil as the mulch broke down. Dyes were often used to cover up an inferior product, which may have included pressure treated wood products. It's kind of like putting make-up on your skin, the dyes are designed to cover imperfections.
How can you find safe colored mulches? Choose products that contain vegetable or soy based dyes, are biodegradable and are MSC Certified, by the Mulch & Soil Council. The package may also state that it is safe to use around food crops. Although to be honest, I would still avoid putting it around food crops, just in case. Plus, it's way to expensive to just be tilled into the soil at the end of the season.
How to apply colored mulch effectively? Colored mulches tend to lose their color over time, so you may want to apply a natural colored mulch on the bottom and top dress with the more expensive colored mulch. You could also use less mulch by placing 6-8 layers of black and white newspaper on the ground first, around each plant, and then placing an inch or two of mulch on top. The newspaper will last most of the season, if not all the season (depends on how much rain you get during the year).
Wood mulches will also leach a small amount of nitrogen from the soil as it breaks down, so you can counteract this by applying an inch of compost to the soil before applying your mulch. This will also allow you to use less mulch.
What are some alternatives to colored mulch? If you have decided to avoid colored mulch for now, whether it's because of the safety issue or you are just trying to save money, there are many alternatives to colored wood mulch.
- Natural Cedar Mulch
- Natural Bark Mulch
- Pine Needles
- Black/White Newspaper with Compost or Mulch on Top
- Cocoa Shells (don't use if you have dogs)
- Straw - Excellent for Vegetable Gardens
- Hay - May Include Weed Seeds (Use with Caution)
- Untreated Grass Clippings
- Ground Cork (May not be Available in All Areas)
- Shredded Leaves
In conclusion, colored mulches are safer than they used to be. Purchase from responsible companies that aren't afraid to label their product with all their ingredients. Use sparingly and avoid food crops if possible.