Is compost made of poison hemlock safe?

We have a significant amount of hemlock present in areas that the cattle that previously resided on our land frequented.  Last year was our first full summer on the land, and some of the hemlock made it 8 feet tall. My goal for the next few summers is to prevent as much of it as possible from blooming to help cut the life cycle, but part of that is going be creating a lot of poison hemlock that's rotting down. We have a young dog, and now have friends with kids, and i want to be careful not to create a situation where the kids might be exposed to hemlock toxicity.

First - is hemlock indicative of a nutrient deficiency?  
Second - when rotted/composted (let's assume a cold compost heap), will hemlock's toxicity be transferred to the compost that it creates or does it break down?
Third - if the compost is toxic, I'd assume it's not a good idea to grow little greens like lettuce in it, but would something like pumpkins or tomatoes be safe to eat?

To remove the weeds by pulling, wear rubber gloves and protective clothing and follow up with an herbicide to prevent future growth. Hand-pulling of poison hemlock works best with young plants or small infestations in wet soils. Mature plants should be dug up and removed. Once the plant and its roots are extracted from the ground, place the plant into a plastic garbage bag and dispose of it into a trash receptacle. Wash all clothing and tools afterwards. Do not attempt to compost poison hemlock as the poisons are persistent. Even the use of weed trimmers needs to be conducted using precautions so that plant material doesn’t come into contact with the body.

This article by George Hurd is an environmental/ resource development educator with Penn State Extension in Franklin County.

https://www.publicopiniononline.com/story/life/2016/09/04/lawn-and-garden-poison-hemlock-beekeeping-and-compost/89876474/

Based on this information Poison Hemlock would be best disposed of in a way other than composting. The article says black trash bags in trash receptacles.

Protect all folks cutting this by wearing rubber gloves and washing all clothes afterward.

If this were growing on my property I would not let it go to seed if I could not do anything else.

I know nothing about organic herbicides as I have not used them:

https://ucnfanews.ucanr.edu/Articles/Feature_Stories/Organic_Herbicdes_-_Do_They_Work/

I have read here on the forum about using corn gluten as a herbicide:

https://permies.com/t/173681/Corn-Gluten-Pre-Emergent-Herbicide

Anne Miller wrote:

To remove the weeds by pulling, wear rubber gloves and protective clothing and follow up with an herbicide to prevent future growth. Hand-pulling of poison hemlock works best with young plants or small infestations in wet soils. Mature plants should be dug up and removed. Once the plant and its roots are extracted from the ground, place the plant into a plastic garbage bag and dispose of it into a trash receptacle. Wash all clothing and tools afterwards. Do not attempt to compost poison hemlock as the poisons are persistent. Even the use of weed trimmers needs to be conducted using precautions so that plant material doesn’t come into contact with the body.

This article by George Hurd is an environmental/ resource development educator with Penn State Extension in Franklin County.

https://www.publicopiniononline.com/story/life/2016/09/04/lawn-and-garden-poison-hemlock-beekeeping-and-compost/89876474/

Based on this information Poison Hemlock would be best disposed of in a way other than composting. The article says black trash bags in trash receptacles.

Protect all folks cutting this by wearing rubber gloves and washing all clothes afterward.

If this were growing on my property I would not let it go to seed if I could not do anything else.

I appreciate the link, I'll give it a read tomorrow.  It is not realistic for us to throw away literal acres worth of hemlock in black plastic trash bags.  I'm planning to do everything I can to prevent it from going to seed, and expect this will take a few years, but honey production is one of the reasons that I'm planning to go so hard on this now, I would really like to get bees in the future.  

If you cannot dispose of the poison hemlock as the article suggests, what do you plan to do with it?

I feel chop and drop is too risky for you and your family or even you neighbors.

Maybe composting is the best thing to do though compost in an out-of-the-way spot and mark the spot "poison" and keep it covered with a tarp to keep it from blowing away.

Thanks all.  Yeah, it's not great, and it sounds like since the toxins persist long enough to be dangerous for a few years, it's going to be a matter of being very clear with our friends and their kids who use the land about the dangers of hemlock and areas that they should be especially cautious.  And realistically, limiting biomass production.  In this case, in able to manage as much area as I need to, I'll likely look into some sort of organic herbicide, or something adjacent, it seems the risk of poison with targeted herbicide application is lower than the risk of poison from the huge amounts of hemlock.  I believe that we are lucky in that the hemlock is primarily in areas that the cattle had frequented and disturbed soil (ridge lines, under trees, working areas) so locations are at least predictable.  Yes, managing the seed bank and preventing biomass and seed production are at the top of my list.  I really do want bees one day, but I need to be sure I'm not producing poison honey first.  


I'm less concerned with livestock consuming it, there were cattle on the land and they all seemed fine, and there is anecdotal evidence that sheep and goats can consume small amounts without getting sick.

I like to sheet mulch over mine as a series of spot mulches, which effectively composts it against the soil surface.  Not sure that it would be practical for you though based on the area and amount you are describing.

Greg Martin wrote:I like to sheet mulch over mine as a series of spot mulches, which effectively composts it against the soil surface.  Not sure that it would be practical for you though based on the area and amount you are describing.

In the garden area, this is exactly what I did last year in phase 1 of garden expansion before I even considered the toxicity of the hemlock.  This is likely what I'll do for phase 2, we didn't notice any issues with toxicity of anything that we consumed out of the garden, but we also didn't grow any root vegetables or fresh greens last year, just tomatoes, okra, and squash.  I'll likely keep the areas known to have hemlock as areas that get left in this type of production (or potentially areas that just get sheet mulched and used as walking/hangout areas) while we wait a few years.  The larger zones that are full of hemlock are a larger problem and sheet mulching that much space is also not a viable option, but killing it off and keeping it dead (thus not producing biomass) should be a feasible option.  

...It is known that drying of fresh C. maculatum under the sun for seven days produces an important loss of alkaloids, although contaminated hay has caused deaths in cattle.

From here: https://alfalfa.ucdavis.edu/+symposium/proceedings/2006/06-71.pdf
Sounds like it might be a good idea to cut or dig up the plants, let them dry under the sun for a good long while, and then sheet mulch the crap out of the whole area...

I know this is an older post, but I've been thinking a fair amount recently about what I might try to do with some unwanted toxic plants that seem to be growing pretty rampantly on our land. Particularly ones which I'm concerned might resprout from being chop and dropped since that is the obvious answer or put into compost even if done before going to seed (but especially after).  

So far, I think the most likely options I have come up with are:

1) Gather up as much of the plant material as possible and pack it into a retort for making biochar. No chance that will resprout, and should easily break down the toxins. I think a properly designed kiln should burn clean enough you wouldn't need to worry about breathing it (not sure if burning hemlock is typically dangerous like poison ivy is?). But maybe need to wear a well fitted and properly rated mask just in case?

2) Move a 55 gallon barrel with sealable lid out to the area to be cleared and begin packing it in and layering for a bokashi fermentation, which I am assuming would safely break things down (including seeds if necessary). Would be ideal to double check that assumption though that the fermentation process breaks down the toxins.

3) Similar to #2, but instead of bokashi just pack it in the barrel and then fill the barrel with water to let anaerobic bacteria set to work that way.

4) Can worms eat poison hemlock? (I've wondered the same for poison ivy and other similar plants too.) If so, perhaps one of the simplest options would be to try something like a Johnson-Su Bioreactor, but filled with problematic plant materials rather than leaves.



I made a very similar comment recently on a post in the fungus section of the forums.  I guess my go-to ways for getting rid of problem materials are pretty standardized... but in this scenario I do find myself left wondering if there is any danger of the toxins remaining after fermentation.  Or in the case of #4, whether I'd be killing all the worms in my experiment...

Hi John,
I just purchased land on the California/Oregon border and found out it's pretty well covered in Poison Hemlock.  Everyone here says DO NOT BURN IT. The fumes are as toxic as eating it. This is my first rodeo with the nasty stuff, so I may be overreacting due to inexperience, but I'm betting your neighbors would really appreciate you not putting that in the air. My own Grandmother nearly died because she drove past a prescribed burn that was full of Poison Oak. It got in her lungs. It's a whole lot less toxic than Hemlock and a few others.

The best answer I've gotten is to bag it up and send it to a landfill. It will supposedly decompose in the bag and the toxins will dissipate over time, without harm. I hope that's true.

As far as Bokashi, no clue. The seeds are the most toxic part of the plant, if my info is correct.

The water barrel may just give you a large amount of poisonous water to contend with. Hemlock toxin can survive for 3 to 5 years after it dies (I think).

The bioreactor is well outside my scope of knowledge, so I'm useless on that one, sorry. Sounds awfully cool though.

I'd be afraid I'd kill a bunch of worms and still have a problem.

I hope this helped, or at least gave you something to look up.

John Warren wrote:I know this is an older post, but I've been thinking a fair amount recently about what I might try to do with some unwanted toxic plants that seem to be growing pretty rampantly on our land. Particularly ones which I'm concerned might resprout from being chop and dropped since that is the obvious answer or put into compost even if done before going to seed (but especially after).  

So far, I think the most likely options I have come up with are:

1) Gather up as much of the plant material as possible and pack it into a retort for making biochar. No chance that will resprout, and should easily break down the toxins. I think a properly designed kiln should burn clean enough you wouldn't need to worry about breathing it (not sure if burning hemlock is typically dangerous like poison ivy is?). But maybe need to wear a well fitted and properly rated mask just in case?

2) Move a 55 gallon barrel with sealable lid out to the area to be cleared and begin packing it in and layering for a bokashi fermentation, which I am assuming would safely break things down (including seeds if necessary). Would be ideal to double check that assumption though that the fermentation process breaks down the toxins.

3) Similar to #2, but instead of bokashi just pack it in the barrel and then fill the barrel with water to let anaerobic bacteria set to work that way.

4) Can worms eat poison hemlock? (I've wondered the same for poison ivy and other similar plants too.) If so, perhaps one of the simplest options would be to try something like a Johnson-Su Bioreactor, but filled with problematic plant materials rather than leaves.



I made a very similar comment recently on a post in the fungus section of the forums.  I guess my go-to ways for getting rid of problem materials are pretty standardized... but in this scenario I do find myself left wondering if there is any danger of the toxins remaining after fermentation.  Or in the case of #4, whether I'd be killing all the worms in my experiment...

Idea:  What if it was composted and used to feed plants that you aren't directly eating, like shade trees?

Riona Abhainn wrote:Idea:  What if it was composted and used to feed plants that you aren't directly eating, like shade trees?

Riona,

You may be on to something. Composting normally breaks down toxins, so it may be enough to use for shade trees safely. I'd look up information until my eyes bled to be sure it's safe. Ok, maybe not THAT much looking, but I am a bit paranoid.
It's the alkaloid component that does the damage and lingers the longest, I think. I honestly don't know if composting would do it, but safer with shade trees than food.

I've got poison hemlock on my land, too. I've read research articles saying it can be composted but can take 2-3 years to be "safe". Definitely don't burn it, the smoke will be toxic!

I intend to handle it the same as humanure - a covered compost heap well out of the way of humans and animals that's given at least 2 years and ideally 3 before being used on trees or shrubs. The hemlock plants would be decomposing on the land anyway if nothing is done about them.

I won't grow food in the areas where the hemlock was growing for at least two years for that reason, but I think planting trees there should be fine.

My goats loved to eat poison hemlock,so much so they eradicated from a rotationally grazed small pasture i had them in once a month,they ate flowers leaves and stalks.Never saw them get sick and they would eat it from free ranging areas as they came upon it.They never ate the seeds though,once it developed seeds they would ignore it.They loved it in early spring when it was the most advanced "weed" around.I have cut it bare handed with a machete and piled and dried it,then set it on fire or let i compost in place,never been sick from it.Just wash off after it being on your skin and wear gloves.Always use caution and common sense around poison plants and if your not sure just stay away from it all together.

Shookeli that is interesting and totally the characature of goats we'd think of when we make jokes about goats, eating tires etc. even though they can't really do that.  But they really seem to eat anything from nature so if anything can eat poison hemlock then it would definitely be goats!  Do you drink milk from them or are they the weed control service for your property rather than providing nourishment for you?

I only had them for the meat market along with brush clearing but no longer have them.They became more of a nuisance to my garden plants.I guess cabbage taste better than hemlock,who knew right? Goats really do eat many plants poison to humans.They love poison ivy too.

So maybe if goats eat it then their milk and meat would still be safe, as long as that's not all they eat?  Interesting and useful knowledge.

I never used or drank the milk from those goats but they had babies who did and no ill effects that i saw from eating anything from those pens.You could have the milk tested for any toxins to be safe.I would assume the meat would be safe as it would be cooked.Goats are really good at brush and weed control so i believe God made them to dispose of some of the toxic plants in the environment to keep them in check.

Everything has a purpose and im sure hemlock has it usefulness for something,identifying rich soil is one because it does not do well in poor soil.

We're talking Anacardiaceae here. Please don't freak out. I would guess that compost made from Poison Oak is safe if the compost reached normal temps and there was mineral soil and other primary ingredients present. But: if you don't need to mess with the Poison Oak/Ivy/Mango/Cashew why not leave it alone?
You are probably wondering if I am crazy already. But consider: have you ever made the mistake of eating an improperly roasted cashew? Have you ever eaten a RAW Cashew? Probably Not: raw cashews have been heated already. Cashews and Poison Oak are close relatives. Now have you ever seen Poison Oak/Ivy in bloom? Smells real nice. Makes gorgeous white honey that doesn't crystalize. Guess what? I ate lots of honey from Poison oak during my decade at Lost Valley and haven't reacted to Poison Oak since. Poison Oak Honey gets a premium price! I could tell lots of horror stories but I'll keep it to one: during my bicycle trip across Canada with a lover (her idea) we had a bit of a romp one sunny afternoon but after I saw there was some poison ivy around (same genus as P.O.) You can guess where welts appeared, and we were on BICYCLES. When we reached the closest point we planned on to N. Wisconsin where my family lived my brother and some of his buddies met us in Ontario and brought prescription drugs (and relief) to us.
I did a guest spot at a "Raw Vegan" permaculture course in Seattle. "Raw Cashews" were present at dinner, lunch and sometimes breakfast. Ever eat a raw cashew? I got some along the coast highway north of Mombasa from a vendor on the roadside that were not carefully roasted and DAMN what a bellyache. You have not eaten a truly raw cashew. They've all been heated to some degree to drive off the irritant oils. But the Cashew "Pear" (from which the single cashew "nut" hangs like a comma) is a sweet edible fruit and can make a fruit wine or fruit leather as well.
So poison oak berries are massively yummiferous for birds, in fact a Eugene resident and retired ecologist and bird expert was able to show how important the seeds are to birds (just like raw vegan permies) that he successfully got the plant put on the MANDATORY restoration list for replanting after highway work where climatically appropriate by Caltrans. The opposite approach was shown at the Willamette Park Disc Golf course there was a Poison Oak vine of FOUR INCH caliper 30 ft+ up a maple on one Fairway. Hysteria ensued and it was cut down and pulled off. Of course they didn't dig out the roots and it stump sprouted right where discs landed. Living at Lost Valley I started telling people you just need to talk with the innocent plant and it will leave you alone. BTW, the wood is beautiful, and the genus includes South African trees with wood streaked with pale yellow, charcoal gray and salmon pink, but don't mess with the leaves. What did the parks staff in Eugene do where poison oak was all over on the top of Skinner Butte? Cut the vines that were climbing up the trees, so it sprouted up ALL OVER the Fairway. Try sitting down there after a mowing. "just say KNOW" If your compost has heated up, if the needed ingredients (soil, nitrogen source, water, etc,) were present, you're OK, just don't set your raw compost on fire, eh? If you know you really react to poison oak and are living in the tropics, don't eat mango unless some else peels it, eh? Then eat some Mango honey!

Maybe making a compost tea of poison hemlock would kill poison hemlock?

That is a known weed killer technique, right?

That's an interesting idea, Anne!