I think that you're fine using anything as long as it remains on top of the ground, not mixed into the soil.

I'll bet it was Juglans nigra (Black Walnut) because of concern about juglone. Actually a number of different plants produce some negative-allelopathic chemicals. Black walnut is just the most recognized for such. I have heard people claim that black walnut chips had an impact on plants that they were applied around. As the chips brake down, they would send some juglone into the soil.

i would NEVER keep stump grindings..

if not completely removed from the grinding hole... it will be along time before you can grow anything there as the rotting wood steals all available water and nitrogen ....

and the same.. as to anywhere you move it int he garden..

EXCEPT for a compost pile for a year or two ...

i dont know about the juglone issue on SURFACE applied mulch ....

free is free... and i tend to let piles stand for a year ...

but my gut is wondering.. how deep you would have to apply the mulch.. to create a toxic level of such... i mean really.. a 3 inch deep cover of mulch.. on a give square foot.. shouldnt really release so much juglone.. to toxify that one foot of area...

but my gut has lied to me before.. and i dont have any experience with it ...

this is right up there with suggesting that pine needles will affect soil pH ... which is an exponential function ... well.. yes it will ..... if you put 100 feet of needles on a spot for 100 years.. yes.. you might actually change pH .... as in the floor of a mature forest .... but that is not really how it will work.. in a standard garden ...

anyway.. let them get rid of stump grindings.... but for compost pile for a year or two ..

ken

Eucalyptus? Seems I heard of that somewhere. Our Wal-Mart has bags of this mulch, so I may be wrong.

You just can't till it into the soil. It causes no harm if used on top of the soil as a mulch. We use hundreds of yards of it that the local tree service gives us at no charge (it's not particularly attractive). We use it around our barns and in our commercial areas where the coarseness of the chips is not a problem as no one gets up close to it.