Composted walnut leaves are fine for all gardens/plants. Use the free compost!

I dealt with the juglone problem while sharing a garden at a neighbor's place with 2 huge English walnut trees. I did some research and forwarded the results to him, and I think they may be useful for you too.

Here are 2 articles about the toxicity from English Walnut trees. Unless your trees are grafted to a black walnut root stock, the amount of juglone is much diminished. That said, they still suggest keeping certain plants away from the roots and drip line of the trees (like tomatoes & potatoes). There's a list in one of the articles.

http://www.hort.purdue.edu/ext/HO-193.pdf
http://www.omafra.gov.on.ca/english/crops/facts/info_walnut_toxicity.htm

They also suggest that you should be able to compost those leaves for future use. I read that it takes about 30-40 days for juglone to break down. One of the best ways of dealing with what does make it into the garden, is to have more organic matter, hence more microorganisms, which are happy to consume and break down the chemical as part of their daily diet. Unfortunately, those bugs don't like massive quantities of commercial fertilizers (kills them), nor do they behave well when rototilled (population explosion then an early demise).

Since they are municipal leaves I don't think there is any way for nevermore to know what kind of walnut trees they came from. Around these parts (MO) there is a significant population of native black walnut. I don't know an English walnut to look at it, but the black walnuts (with or without husk) are easy to identify.

Anyway hopefully the articles posted above will have the answers.

Thanks for the info. They would most like be black walnut in this area. They will be mixed greatly with many other species of leaves and i don't use synthetic fertilizers.. so if it degrades over 30-40 days... i suppose i will be just fine. I guess i could always do the tomato seed germination/growing test to check every once in a while.

The only "problem" I have seen with using only the leaves from a Black Walnut tree is that the Quack Grass growth was suppressed but the Perennial Rye grass was not. When the Black Walnut leaves are mixed with other tree leaves there has not been any observed problem.

There are some tWo hundred plant that can be harmed from the Black walnut & juglone.
But compost from the leaves of walnuts & pecans have not hurt my plants.
I even mulched some tomatoes with pecan leaves one year & got a good crop.
I was not watching what I was doing & mulched with the wrong bag of leaves.

mustgarden, would love to be able to read what you read, "I read that it takes about 30-40 days for juglone to break down."

Do you remember where you found that info? I asked a similar question about juglone in compost with a lot of pecan shells and didn't get any info this specific.

Do a google search on "Juglone" and you will find a number of short articles by state universities. Some have lists of plants affected.

List of affected plants are everywhere, and are published in regard to growing within the drip line of a walnut tree. I would like to have some info sources about how long the juglone takes to break down, the topic of this discussion.

From Ohio State University:

"Walnut leaves can be composted because the toxin breaks down when exposed to air, water and bacteria. The toxic effect can be degraded in two to four weeks. In soil, breakdown may take up to two months. Black walnut leaves may be composted separately, and the finished compost tested for toxicity by planting tomato seedlings in it. Sawdust mulch, fresh sawdust or chips from street tree prunings from black walnut are not suggested for plants sensitive to juglone, such as blueberry or other plants that are sensitive to juglone. However, composting of bark for a minimum of six months provides a safe mulch even for plants sensitive to juglone."

Here is a link that might be useful: Whole article

Good article, thanks for sharing.