Hmmmm.....walnut trees are known to inhibit the growth of other plants (allellopathy[or is it allelopathy?). I'm not sure what part of the tree produces this allellopathic compound, but I think I would do a little more research before trying a walnut mulch.
Maybe someone on this forum can enlighten us?

wanda

There's a lot of info on Google. I thought for sure that black walnuts were the main offenders, but I guess English walnuts are allelopathic (say that fast 3 times!), as well, albeit to a lesser extent.

Brenda

Here is a link that might be useful: Walnut allelopathy Googled

I can only give you my own experiences with black and english walnuts. The leaves I compost right along with all the other leaves with no problems. I would not use uncomposted leaves as a mulch as they are a slimy mess on the ground through the winter. When I remove a walnut tree the allelopathy from the roots continues as long as the roots are alive. When I remove the stump and stop the root life in the ground within a year I can plant sensitive plants in the area. Al

The use of black walnut compost with vegetables

Summary:

There is no published research showing that composted black walnut leaves result in a product toxic to vegetables. Published research on composted English walnut leaves showed no phytotoxicity to the tested species.

Do not use freshly-cut mulch on any vegetable crop. The bacterial decomposition process will cause a nitrogen deficiency for the crop, regardless of the species of plant used. Based on verified, published research, any plant material, adequately composted ,can be used as an amendment for planting mixes for vegetables.

Do not use pure plant compost of any species as a planting medium for vegetables. Additions of soil, sand, vermiculite, perlite, coir, etc should always be made for reasons such as aeration, drainage, pH, etc.

There are reports involving black walnut roots and bark, but these are not used in most compost preparations. There are observations regarding planting within the drip line of the black walnut and resulting toxic effects. Vegetables should not be planted within the drip line of any tree. This is for the well-being of the tree and the light requirement of the vegetables.

I am too afraid to use walnut mulch... I lived with several black walnuts... I've SEEN their evil ways! :o) There are so many other mulches, why chance it?