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Plants Forbidden For Compost?

Posted by bob64 6 (My Page) on
Mon, Jan 21, 08 at 16:20

The thread on "Help on a couple of questions please" has inspired me to post these questions:

(1) What plants (and fungi, etc.) should never be used (or only sparingly used) for food crop compost due to their poisonous, toxic or otherwise unhealthy nature when the food is consumed?

(2) What plants (and fungi, etc.) should never be used (or only sparingly used) for any compost due to toxic effects on the plants that you wish to grow with the help of the compost?

P.S. Regarding question (2), I have already heard that Walnut, Ailanthus and Norway Maple all have alleopathic properties but I am sure there are other plants of concern or open to debate.


Follow-Up Postings:

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RE: Plants Forbidden For Compost?

Technically, a complete and finished compost has decomposed any ingredients into their base chemical constituents such that, they no longer retain the toxic properties of their previous compounds.

That being said, a lot of people use partially finished compost or compost in place... and then one might want to be more prudent about what goes into the pile.

I personally won't compost Poison Ivy, because I am very allergic to it. I am not concerned about poison ivy urishol in finished compost, but I am concerned about possibly contacting it, while working with the pile, before it is finished. I don't want the urishol on my tools, on my gloves etc.

I have composted walnut leaves, but they were a very small component of many different types of leaves and the compost was finished and aged before it was used.


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RE: Plants Forbidden For Compost?

  • Posted by whip1 z5 ne Ohio (My Page) on
    Mon, Jan 21, 08 at 17:45

For me, it's poison ivy. Besides the fact that I don't want it in the pile, I have no idea how to get it into the pile. It's one of the few times I use Round up.


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RE: Plants Forbidden For Compost?

Among other things, I was wondering if some plants that are poisonous when ingested directly (like digitalis or milkweed) could still send poisonous or harmful substances via their composted remains into food crops grown with that compost. So far it looks like y'all are saying it's not a major issue.


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RE: Plants Forbidden For Compost?

Milkweed gets composted or chopped & worked directly in to the soil in my garden. (There's always some growing in the garden that I leave for the Monarch butterflies.)

Since I get poison ivy just by thinking about it, I wouldn't compost it, much less go near it. I don't know how the heat of the compost would affect the oils which cause the irritation though I think a hot pile would make oils dissipate.

The chemical compunds in the plants that are toxic to us when ingested are generall broken down during the composting process. I've read warnings about Eucalyptus and Walnut, but I'd suggest that unless these were the predominant organic material in your compost, the concentrations of any compound harmful to other plants or you would be miniscule.

Wayne


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RE: Plants Forbidden For Compost?

I think you are safe to compost any plants. I have used walnut leaves and worse Ollie Ander leaves. Those Oliander lives are very toxic but I found worms eating them when raked in a pile, although they were dried leaves and not green.
The only thing that you should not put into your compost plant wise is diseased plants. Like black moldy tamatoes, ufrasion tamatoe plants, any disease should be in the trash can. Rotating your crops help with this. Also the leaves from a peach three with curly leaf, if you pick these off throw them in the trash can. That is what I would do. BIllC


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RE: Plants Forbidden For Compost?

Like many others about the only plants I will not compost would be Poison Ivy, Oak, and Sumac. I regularly compost Black Walnut leaves and would compost diseased plant tissue if I had any because I have seen much research that says that is okay and none that shows a plant, growing in good, healthy soil, would get that disease from my compost.


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RE: Plants Forbidden For Compost?

I don't compost spent tomato plants, not out of any concern for toxicity, but because the chance of the pile heating up enough to kill all the pathogens is remote, leaving the capacity to spread plant disease by applying the finnished compost.


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RE: Plants Forbidden For Compost?

If the composting process is thorough, with high enough temperatures achieved and maintained for a sufficient length of time, no plant material is forbidden, neither those with allelopathic properties or those containing disease pathogens. The process will break everything down into its elemental forms, rendering them harmless. A proper composting process is a great equalizer - the end result will be of uniform quality and substance regardless of the quality and composition of the initial ingredients. That is the entire point of composting.


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RE: Plants Forbidden For Compost?

If I'm not sure the compost will get hot enough, I avoid bindweed, especially the roots and seeds, but if I know it'll get hot enough, I'll compost anything.


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RE: Plants Forbidden For Compost?

I'm with BP, only my forbidden plant is horseradish. I've seen dock and dandelion roots survive composting, too, but they're easy to pluck or sift out. But I don't trust horseradish not to take over the world. I let the castoff roots rot in a bucket of water until slimy before throwing them into the heap.

Here is a link that might be useful: my website


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RE: Plants Forbidden For Compost?

Is it a good idea to add Norway maple seeds to the compost pile? Or will I have trees sprouting in there just like all over my yard and beds??

I have raked up a trash bag full and am wondering if I can just leave it in a corner of my garden or should I just toss it out? There is some hardwood mulch mixed in.


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RE: Plants Forbidden For Compost?

There is some research out there that indicates that it is not the heat of a compost pile that is needed for control of weeds and seeds but the length of time they are composted. Same thing with potentialy diseased plant material, the longer it is composted, not the heat of the compost, is what develops the needed immunities to control these disease pathogens.


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RE: Plants Forbidden For Compost?

Not sure if I would compost materials that had a systemic insecticide/pesticide applied recently such as some of the Bayer products . The label recommends not using these products on fruit bearing plants . If you were using the compost on anything other than edibles then it should not be an obvious problem .
Seems that the time materials spend in a compost would be the most important in mitigating harmful ingredients but again - not sure .


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RE: Plants Forbidden For Compost?

A whole bag full of Norway maple seeds! Oh Boy! If you have gone to the trouble of bagging them up, I would just let them sit for awhile and bake until the seeds are no longer viable. If plastic bag just punch a few holes in the bag, like with a digging fork and it will turn into mush ready for the compost pile when it was ready.

Do as I say and not as I do. I just raked everything up with the excess grass clippings and dumped it into the compost bin with a nice layer of browns over it. I guess I will see how much they like it in there. I guess it is finding out the hard way, which I am good at.

Foghorn


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RE: Plants Forbidden For Compost?

I probably wouldn't compost fake or plastic plants...


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