solarization of comfrey

I have a couple hugel beds that have been overrun with Comfrey (not the sterile kind). If I were to try and solarize these beds would I likely be successful in killing off the comfrey? There are some pretty deep rooted ones in there. Clear plastic is my best bet? Thanks!

I am not a fan of that form of solarization.

It is possible that while doing this a person is also killing or weakening the soil organisms.

Why not use a method of smothering and blocking out sunlight by creating a thick mulch of wood chips, leaves, etc?  Anywhere from 6 inches to 12 inches will do this.

As this mulch breaks down it will add organic matter to the soil.

Why not use a method of smothering and blocking out sunlight by creating a thick mulch of wood chips, leaves, etc?  Anywhere from 6 inches to 12 inches will do this.

I have a bocking 14 variant so it may be different, but 6-8 inches of wood chips did nothing but slow my comfrey down and protect it from a late frost we had after our annual false spring. The leaves didn't even look weak or sickly whatsoever when they popped through! Maybe 12 inches would suffice, but I don't put anything past comfrey.

The one time I had to kill a flourishing plant, I waited until it started to wake up in spring soaked the area and put a 3 inch layer of whole, compacted damp leaves from last fall down with the intent of creating a wet enough environment to get some root rot going. I then topped the leaves with two pieces of cardboard all held down and buried in 6 inches or so of wood chips. That was two years ago and, so far, no comfrey, but I keep at least 6 inches of woodchips on top.

As so your original question about solarization, I have never done that, but I know of no reason why it wouldn't work in time. My only concern is in line with Anne's; you'll have to kill just about everything and everyone to ensure that the comfrey is also dead and gone.

Good luck obliterating one of my favorite plants!

Comfry won't be slowed by 6" to 8" of woodchips. It will push straight through and thank you for extra soil fertility.

I'm sure if you chop'n'drop it every week, you'll eventually run the roots out of energy.

Christopher Weeks wrote:I'm sure if you chop'n'drop it every week, you'll eventually run the roots out of energy.

I would love to know how long that would take!

Will Whitt wrote:

Christopher Weeks wrote:I'm sure if you chop'n'drop it every week, you'll eventually run the roots out of energy.

I would love to know how long that would take!

Pick a plant and a lopper and get to it! let us know when you have an answer :)

I'm aware of the potential of making the soil sterile but I figure I have boatloads of compost and other organic material to revitalize it afterwards. There's a portion of one bed where there are wood chips at least 12",  deep and it doesn't phase the comfrey. If I were an earthworm, sow bug, millipede, or other relatively mobile creature I'd be certain to find another domain to inhabit as the temperature increased. I don't know about all the other tiny critters like nematodes, bacteria, etc. But I would think that the soil would repopulate with those also eventually. The problem with chop & drop is I have way too much of that to do in other areas and I just can't seem to keep up with it.

I just read an account of ducks eating comfrey so aggressively that the comfrey died out. So I came running back here to share. :)  Still doesn't address the solarization enterprise, but it seemed like logging it here might help some people in the future.

Ducks.... Been thinking of ducks again since I lost my pair of Indian Runners to a mink a few years ago. I don't recall them ever chomping on the comfrey much but there wasn't nearly as much of it back then. Thanks for the tip!

I also don't think you can kill the  roots with solarization without really hurting the soil.
Maybe solarization, followed with black plastic, then cover crop then repeat, until they are tired out.
This could feed the soil while hurting the comfrey.

Will Whitt wrote:The one time I had to kill a flourishing plant, I waited until it started to wake up in spring soaked the area and put a 3 inch layer of whole, compacted damp leaves from last fall down with the intent of creating a wet enough environment to get some root rot going. I then topped the leaves with two pieces of cardboard all held down and buried in 6 inches or so of wood chips. That was two years ago and, so far, no comfrey, but I keep at least 6 inches of woodchips on top.

This!

The key is to get the mulch, leaves, wood chips to block out the sunlight.

Also the patch has to be large enough to cover the whole area where roots might be.

Anne Miller wrote:I am not a fan of that form of solarization.

It is possible that while doing this a person is also killing or weakening the soil organisms.

Why not use a method of smothering and blocking out sunlight by creating a thick mulch of wood chips, leaves, etc?  Anywhere from 6 inches to 12 inches will do this.

As this mulch breaks down it will add organic matter to the soil.

Comfrey will punch thru that like it is nothing.  Guessing would probably need to be 4 feet or more deep to work.

Michael Cox wrote:Comfry won't be slowed by 6" to 8" of woodchips. It will push straight through and thank you for extra soil fertility.

You are not kidding! I put down about a foot of arborist chip mulch over where I planted comfrey thinking I had killed it off. I have attached a picture of what I have discovered this very afternoon.

What a resilient plant.

Even if you dig up a bed of comfrey, unless you get every single segment of root out, I have found that it will regrow.
Perhaps you could post on a local gardening group for people to come and dig up as many comfrey plants as people want and then sieve through the soil to remove any remaining fragments.
Are there any local herbalists who might want some roots for making salves and tinctures?

My feeling is that mulching probably can work... with the caveat that it needs a pretty tough biodegradable barrier under the chips.  Double or triple layer cardboard, combined with the chips on top might be successful where chips alone will almost certainly not be.