Of course, there will be conflicting input on the subject, but here's some information on dyed mulches:

The most common ingredient for turning mulch black is coal. Water-based paints and natural vegetable dyes are also commonly used. Black mulch dyes can also include chemical binders and preservatives that assist in the coloring process. There are also dyes made from the materials created by incomplete petroleum combustion. This specific type should be avoided because the dyes are carcinogenic and can be harmful to both the plants and the soil itself.

Some manufacturers use chromate copper arsenate, a toxic element to garden plants and other living things, to treat their wood. To be safe, it is best to purchase raw wood pieces that have been treated naturally

Molly

and it looks crap after a couple of weeks in the sun lol. Get something natural and then you don't have to worry.

Good for Molly.
I've never looked it up, but one look at the stuff told me it was probably not a good thing to put into a garden. There's something awfully 1950's about dyed MULCH.

It's like a shocking pink, or electric-blue Christmas Tree.

I wouldn't use it if someone gave it to me.

Jeri

hmmm, it would offend my sense of aesthetics.
Suzy, who currently has a nice pinky purple hair fringe (I think you call 'em bangs)

I honestly don't know much about the chemistry of the dye and whatever, but I've heard (probably here) that dyed mulch tends to leach nitrogen and whatnot out of the soil. I use bagged organic hardwood mulch from houston garden centers and my plants really seem to like it. I think everyone else in my neighborhood uses the dyed mulch.

I used black (dyed) mulch that my daughter gave me that was left from their spring mulching 3 years ago. A few weeks into the spring bloom period I saw that the petunias, lobelias and snapdragons that I grow in that bed every spring (for the last 10 years)were runty and not vigorous at all. I thought nothing of it, assuming the weather may have been the contributing factor for the poor performance and lack of vigor. When the spring annuals were dug up and I replaced them with my summer zinnias, coleus and other annuals, I again had a very disappointing bloom season. I attended a seminar in July of that year and the subject of mulches was the centerpiece discussion of the day. Only then, when various members talked about the devastating effects of dyed mulch on their gardens did it occur to me that this was the problem in my flower bed. I scraped off all of the black mulch and replaced a good part of the soil, knowing that the problem would have gone beyond the layer of mulch. In the case of this particular product, the effects were long-term (3 years) in my garden.
Molly

Molly, did you notice any deleterious effects 'downstream' from the mulch, where rainwater would run off?

Lucille, the bed I am referring to in my garden is a raised 1/2 circle bed that is surrounded on the back side and the north side by our concrete driveway, the front edge and south edges of the bed are surrounded by a river rock path so there is no soil area that comes in contact with it. My daughter (who gave me the mulch) has used this type of mulch for the six years she has lived in her new home. Most of her foundation shrubs have either died or have declined enough to warrant replacement since she moved in. I guess it could be coincidence, but I don't think so. I believe the deterioration is insidious and, therefore, undetected by the gardener.
Molly

So, yesterday I came across an ad that is even more outrageous than dye for garden mulch. It is a grass dye, you dilute it in your sprayer and spray it all over your lawn to make it greener.

Oh gezz there is a dye for grass!! HAHAHA wow

Spraying the grass green was quite common decades ago when I lived in Lubbock, Texas. No snow in the winter, so all there was to look at was brown grass for several months on end. Lubbock's solution: every winter, spray the grass green. Weirdest thing you ever saw. I nearly caused a car accident the first time I passed by a big yard with newly sprayed green grass in January.

Ugly too, I might add.

Kate

I figured the grass stayed green as long as its watered..

The dyed mulch is chipped wood that has not been composted. You are spreading raw wood on your soil. Proper composting of identical chipped wood would take a few weeks. Dying it with a chemical takes a few minutes.

The net-net is:
1. Uncomposted wood is more likely to attract ground termites. If this is a problem in your area, keep that in mind. It is not a problem in all areas.
2. It means more profit margin for the corporation.

I don't like it myself. The colors look very unnatural, and I would rather support small local compost businesses, and compost my own yard waste for use as mulch.

Huh. I wonder if some of my neighbors dye their grass? It wouldn't surprise me!

Thanks for this very informative thread!

I had some black dyed mulch that my mom brought over and was about to use it over all three of my new rose beds! So glad I saw this.

We did black mulch in the front of the house a few years ago where we had planted three small pine shurbs and some hostas and they were surviving (but had some mystery dead spots we couldn't figure out) and definitely not thriving and now I'm betting it had to do with that mulch!

BTW I actually emailed a dyed mulch company with my concerns, instead of taking me seriously they glibly assured me that nothing in their mulch could hurt my plants.
I'm inclined to believe the experiences I read here over assurances from a company that has a financial stake in dyed mulch sales.

Many warm season grasses turn brown and go dormant after the first freeze. Bermuda grass, very popular in the south does this. It looks like straw. Everyone has it, so it doesn't look bad (until the weeds start popping up). At lest we don't have to mow all winter long!

I thought people were dying their grass green, but the landscapers put food coloring in their spray to see where they have sprayed. It does look weird though.