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Dyed Black Mulch: Safe for Plants, But Dye Is a Trade Secret

Black mulch is dyed (zinc-based paint likely), and you can even buy dye to refresh faded mulch. The dye formula is a trade secret, but no evidence shows harm to plants.

Practical Take

Dye doesn’t leach toxins at harmful levels.
Mulch benefits (moisture, weed suppression, soil temp) outweigh dye concerns.
Use it if you like the look.

Source

Mulch dye FAQ: pinestrawdirect.com

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