When NOT to plant comfrey

I've read a lot about the benefits of comfrey. But what about the drawbacks?

Each organism has its place, and the more we learn about them, the better we can put them to their best use--the one most in line with its nature, and the best use to us at the same time. That means, conversely, that if every plant has a place it belongs, there's a place it doesn't belong as well. I keep hearing comfrey comfrey comfrey... but when/where NOT to plant it?

(Now, I know many of you adore comfrey. I hope you won't run away shouting, "Heretic!" as my fellow English literature students nearly did when I told them I couldn't stand Wuthering Heights. Sorry Wuthering Heights lovers.)

I've got a weird little raised bed in an awkward spot. It has comfrey in it. I noticed it last year. What I don't yet know is whether it's true comfrey (propagating by seed and root fragments) or sterile "Bocking 14" Russian comfrey (only propagating by root). In the fall, I didn't think to save some seed and try growing it, but I will this year.

I'm currently deconstructing the bed and deciding what to do with that soil. It's lovely soil, and I've been sorting through it to find the viable comfrey roots so I can plant some where I want them. That said, I may not have found them all... and there may be viable seed in the soil as well... so I don't want to put that soil anywhere I'm going to regret.

For instance, I've heard it's a no to plant comfrey (deep rooted) under (especially within 4 feet of) an established apple tree. Basically, "You must plant them at the same time so the shallow apple roots can grow around the deep comfrey roots.) Is this true? Can I plant comfrey around my already-existing tree to try to give it a boost? Or should I wait?

Are there spots you regretted planting comfrey?

Plants it overshadowed/shaded out?

Places you had it once and now want to do something else with but can't?

A time it didn't work out for you the way you envisioned?

I've heard all about how it's wonderful, but now I want to hear the other side of the story.

I don't have an answer, but I think it's an excellent question!

I haven't got comfrey in my garden and am undecided whether it's worth planting any. I suspect it wouldn't be happy due to heat and dryness.

Last night I took the comfrey root pieces and buried them all (there were lots!) in a long window planter inside. I’m hoping they’ll start growing now even before the weather gets warmer, and once I’ve decided where to put them, I can transplant them. That will also help me find out what size of root pieces did best—I have some 8-12 inch ones and some as small as 1 inch.

If I can find a good spot around the roots of my established apple tree (formerly neglected by the previous owners and badly needing some amendments and pruning), I’ll plant some little pieces under it… around the drip line? Maybe closer? Then chop and drop to help feed the apple.

From what I’ve read, some people plant comfrey a few feet out from their fruit trees, some very close to the trunk.

Reasons not to do this? More ideas on specifically where has worked or not worked for you?

I am new to the comfrey game, but I do have two different varieties of Bockings.

I have placed the current set I have on a hillside where I do not plan to do any digging. Its primary purpose is to put down roots and stop erosion while the secondary is to intercept any chicken run runoff that may occur when it rains. This will serve as chop and drop material.

I have more started indoors from root cuttings that have been doing fantastic. These will be going under my fruit trees. I have given two years for the trees to establish. I don't have any worried about the comfrey competing, especially when I cut them and use them for fruit tree mulch. I'm going to go the route of planting them closer to the trunk for now and see where it takes me.

Timothy Norton wrote:
I have placed the current set I have on a hillside where I do not plan to do any digging. Its primary purpose is to put down roots and stop erosion while the secondary is to intercept any chicken run runoff that may occur when it rains. This will serve as chop and drop material.

That gives me an idea for an area I might want to spread comfrey—we have a hillside that’s just grass at the moment, and a pain to mow. Part of it is technically our land and part is technically the state’s (next to a right of way) and it’s also under some power lines. So I wouldn’t want to put any trees there that the state or a power company might cut down, but I have been considering low easily spreading bushes and little fruits, or maybe a “hedge” with native fruits for wildlife.

If I get more comfrey started from these fragments than I need at the moment, I may plant a few on this hill. It’ll help with erosion; it doesn’t get cut super often; and it will compete well with whatever I plant there eventually.

 I grow the species, divided from wild patches, and have been able to grow them in a bed for a year as a cover crop, transplant them elsewhere, and just have to pull up a few root sprouts in order to have a clean bed. But it does take some watching and trowel work. I think true comfrey is probably less invasive than Russian comfrey, which even though they don’t set seeds, find plenty of ways to spread.

The seedlings are large and grow very straight taproots, so you can recognize and probably transplant them if you find them.

They also don’t like gravel very much, though I have seen a white-flowered specimen growing in pure sand. Comfrey will hog nutrients like a giant weed and send out aggressive fibrous roots in all directions, and deserve a good distance of at least a little more than their rosette spread (about 1ft radius for young comfreys) from other plants, since they will suppress any other growth within that range and even compete with goldenrod. I haven’t grown many trees in the past but would like to hear also whether people consider comfrey beneficial in those circumstances, since they can also be very competitive.

Maieshe Ljin wrote:I grow the species, divided from wild patches, and have been able to grow them in a bed for a year as a cover crop, transplant them elsewhere, and just have to pull up a few root sprouts in order to have a clean bed. But it does take some watching and trowel work. I think true comfrey is probably less invasive than Russian comfrey, which even though they don’t set seeds, find plenty of ways to spread.

Wow, so in your observations true comfrey spreads less than Russian comfrey (even though it can set seed)?

And in that case, do you think I could use the garden soil that I have in a annual vegetable bed (where I don’t want comfrey) and manage to remove any comfrey that grows without it being too much of a pain?

I've read that true comfrey has white flowers, and the Russian kind has bluish/purple flowers. Do you remember which color your flowers were?

Here's an article (which you probably have already read) talking about how Amy at the Tenth Acre Farm uses both. It seems if you're just wanting chop and drop mulch, Russian is probably the way to go. It's also probably what you want if you don't want to be as fastidious about keeping it from flowering to produce seed and spreading. (That's something I would worry about, personally. I wouldn't want it breaking containment and invading the natural areas around me.)

Personally, I'd probably try to grow a bit of both. I don't have any advice regarding growing it around established trees. Maybe keep it out near the drip line just in case though. If the tree is big enough, I doubt something like a few comfrey plants will do it serious harm.

In regards to the question of how close to plant, this thread dabbles a bit in that. - https://permies.com/t/17731/Comfrey-proximity-fruit-trees-close

I think that where I’ve seen Russian comfrey spreading, they probably spread originally on farm equipment. They were growing in the compost pile too, so that’s probably where they started spreading outwards from, as they love to grow in compost piles.

Since you don’t know which kind of comfrey it is, I would be cautious, maybe sift it if you have a coarse screen to get the roots out, and be vigilant with weeding. I suppose it could also help to plant tall, weedy vegetables like corn or tomato. Maybe not squash because you might not be able to see and pull comfrey sprouts as they come up. Another option is to just let them grow for a year underneath the vegetables (they aren’t much of a problem for strong vegetables while they are young), and transplant them elsewhere in summer or fall when the roots are larger and harder to miss. In my experience, comfrey, especially seedlings, will make nice neat taproots that are easy to dig up in deep, loose soil.

I also am suspicious of flower color as a good indicator. My comfrey is certainly true, and the flower are light blue. Go Botany lists flowers as blue to purple, white, or yellow. One way to discern is that true comfrey leaves are decurrent along the stem (wings along the stem) while neither the hybrid nor other species have that characteristic, but it’s not a very obvious feature. I also find that Russian comfrey gets more powdery mildew and grows a bit larger, with darker leaves and flowers.

I did manage to plant comfrey a bit close to my currant bushes once. When the bushes were small the comfrey overtook them a bit, but after a few years it was OK once the bushes grew more, since the comfrey growth hid the bushes just a bit from the birds so I got more of the berries!

In my region, don't plant Comfrey in your driest spot. That plant is barely alive, dying back during our seasonal drought, waiting until spring to try again. Don't plant in full shade. They die. Plants in 6 hours of sun are more than twice the size of plants in 4 hours of sun.

Joylynn Hardesty wrote:In my region, don't plant Comfrey in your driest spot. That plant is barely alive, dying back during our seasonal drought, waiting until spring to try again. Don't plant in full shade. They die. Plants in 6 hours of sun are more than twice the size of plants in 4 hours of sun.

This is why I haven't tried comfrey. I don't think it will be at all happy. I'm wondering about perhaps something from the borage family instead, as they may not be quite as good mineral accumulators but do produce  lot of biomass even in dry conditions and are also loved by pollinators.

I built a crude teepee type thing to set over my comfrey. That gives it dappled shade most of the day. It’s hot here so that works. I harvested the cedar stakes off my property so makes them more awesome imo lol. I do have them hooked into the drip system for the garden though.

UK based. At my home on our chalk soil my comfrey grows, but doesn't thrive. It doesn't do a good job of protecting other plants, or feeding the soil.  I can cut the better plants maybe once a year. Chalk soil tends to be shallow and very dry in the summer, as it is quick draining.

At my relatives place, in south Wales, I planted comfrey around their apple tree. It absolutely thrives. Their location is much wetter in terms of rainfall, but they are also on deep moist soil, with a water table only a couple of feed below the surface. The whole area is reclaimed marshland, criss-crossed with drainage ditches.  Comparing the exact same plants (from root cuttings) in different settings is remarkable. Around her apple tree the comfrey completely suppresses the grass, we get at least two if not three cuts per year, and the apple tree is thriving. The soil beneath is dark with organic matter, full of worms, and always damp even in dry spells.

I'm a big fan of comfrey for what it can do, but in some circumstances it is disappointing.

Joylynn Hardesty wrote:In my region, don't plant Comfrey in your driest spot. That plant is barely alive, dying back during our seasonal drought, waiting until spring to try again. Don't plant in full shade. They die. Plants in 6 hours of sun are more than twice the size of plants in 4 hours of sun.

No wonder the ones in that raised bed were happy last year! They got lots of sun. That’s good news for my hillside spot—it’s south-south-west facing.

Joe Hallmark wrote:I built a crude teepee type thing to set over my comfrey. That gives it dappled shade most of the day. It’s hot here so that works. I harvested the cedar stakes off my property so makes them more awesome imo lol. I do have them hooked into the drip system for the garden though.

Very clever! Does the teepee have horizontally and diagonally woven stakes or mostly just vertical ones? How did you hold/tie it together?

I’d love to see a picture if you have one.

I think comfrey on my latitude would be happy in full sun, but I love that idea in case they’re not—and for other plants!

Michael Cox wrote:
At my relatives place, in south Wales, I planted comfrey around their apple tree. It absolutely thrives. Their location is much wetter in terms of rainfall, but they are also on deep moist soil, with a water table only a couple of feed below the surface.

How old / how big was the apple tree when you planted the comfrey? How far away from the trunk did you plant it?

I have some happy comfrey...and I've killed it occasionally.

A local said his mother planted it and it took over the whole backyard - she must not have deer... My deer learned to eat it in the drought last year, so now I'm concerned more might end up dead, if the deer over-harvest it.

1. I would not plant it where there's a lot of nutrients and plenty of water if you don't want it to take over.
2. I would not plant it where I might have to do a lot of soil disturbance (like a potato bed) as breaking up the roots tends to spread it.
3. This is quite dependent on one's eco-system. My climate is not your climate.

Related question: how do you get rid of comfrey if it is out of control or simply somewhere it's not welcome?
1. Find a way to decrease its access to water.
2. Find a way to reduce the available soil nutrients. (Like by planting other fast growing, nutrient devouring plants.)
3. Find a way to make it work harder than the area can support - like chopping it every few days, and removing the chopped material to somewhere that needs the nutrients.
4. In my soil, I would not try digging it out for fear of spreading or increasing the problem. I would smother it under low nutrient material like fall leaves, or temporarily covering it with the heavy type of pond liner, which will control for light and moisture depending on the time of year.
5. Similarly, in my soil, I wouldn't risk moving soil it was growing in, to a location I did *not* want it. Maybe quarantine that soil in large pots and grow tomatoes or something, so if it shows up, you will know it?

Do not take this to suggest that Comfrey isn't a wonderful plant - I believe it is. However, I know 2 people who ended up with it in their "organic veggie gardens" and were "unhappy" with that fact. One family had enough land that they simply moved their garden to another area on the land, and let the comfrey get out-competed through neglect in the old garden. Not sure if the other family did anything but whine. However, they have made me a bit cautious. However, raspberries are at least as invasive in my ecosystem!

I would also really like to hear others feedback on planting comfrey close to trees.  i planted a few apples last year and put cuttings within a foot of the newly planted trees but they only grew to about 6" tall or so last year so its too early to tell what sort of good or bad it will turn out to be.

Our experience with comfrey:
I have a lovely bed of Russian bocking, almost straight gravel (on top at least there was a driveway right beside it) and full sun.  It does well and we use it to chop and drop and occasionally for medicine.  I later was gifted a comfrey plant and placed it under the newish apple tree...I did not realize it was the standard variety.... and I chopped some and threw it in the compost pile.  
The Russian has pretty much stayed put from what I can tell.   The standard is trying to take over the world.   I don't really mind that it has spread under the tree but compost row I am going to try to reclaim this year.  
Both varieties have a purplish blue flower.  The leaves are slightly different,  and side by side I could probably identify them,  but not it in the wild.
Unless you are digging or plowing your beds,  i would highly recommend Russian bocking.  In my experience,  I would never recommend standard comfrey (pictured).

Simple rule: DO NOT PLANT COMFRY WEHERE YOU MAY NOT WANT IT IN THE FUTURE.   Removing it requires doing as you did several times.
Otherwise use the bounty you have to try it wherever you think it may be helpful and not in the way in the future.
Smothering it out is not a valid plan.   Some was growing but weak where a garden bed had been in the past so I thought it would be a source for propagation.    It was very difficult because it had grown through an impermeable barrier that prevented rain from reaching the roots directly that is wy it was weak but not dead.  

Timothy Norton wrote:
If I get more comfrey started from these fragments than I need at the moment, I may plant a few on this hill. It’ll help with erosion; it doesn’t get cut super often; and it will compete well with whatever I plant there eventually.

Be careful with planting too much on a steep hill, as comfrey leaves die back completely in the winter (and since it kills off grass, there is not a lot of root mass to prevent soil erosion in the winter, as the big comfrey leaves killed off all vegetation under it). Now, if you put a swale at the bottom of the hill, with perhaps some fruit trees, if you plant the hill full off comfrey, those dead comfrey leaves will all collect in the swale and fertilize the fruit trees, without you lifting a finger.

M

Yes I have a couple cross bars. I will grab a pic in the morning

Do you have gophers? Gophers have been the main way comfrey has spread all over my yard. It is one of their favorite foods and they will store it in their burrows for later. I once dug up a gopher den where one had made a pantry of cut roots stacked up like logs. I planted these 1 1/2 inch pieces in my green house and they sprouted comfrey and horseradish. Now I keep comfrey in large pots.

Lydia Feltman wrote:Do you have gophers? Gophers have been the main way comfrey has spread all over my yard. It is one of their favorite foods and they will store it in their burrows for later. I once dug up a gopher den where one had made a pantry of cut roots stacked up like logs. I planted these 1 1/2 inch pieces in my green house and they sprouted comfrey and horseradish. Now I keep comfrey in large pots.

Ooh, we have one big groundhog we named Gaston (large and hairy). He lives very near our garden.

(Out an upstairs window last year I saw him heading for the garden. I ran downstairs and outside and scared him away--he was on his hind legs reaching for the tomatoes. When I looked, I found two teeth marks on the nearest tomato. Caught him in the act!)

The garden area is fenced in this year... hopefully that will deter him. I'll have to keep an eye out to see if he heads for the comfrey once I plant it...

Arliss Wirtanen wrote:I would also really like to hear others feedback on planting comfrey close to trees.  i planted a few apples last year and put cuttings within a foot of the newly planted trees but they only grew to about 6" tall or so last year so its too early to tell what sort of good or bad it will turn out to be.

I'm new to comfrey, so not positioning myself as an expert, but I planted it too close to very young apple trees that I'm growing from seed -- maybe a foot from the tree. It grew up much bigger than the baby trees, so I kept having to cut or step on the comfrey to prevent it from shading the apple. I ended up digging a lot of it up and moving it to be about 3-4 feet from the apples instead. But I only did that last year, so I'll know more in six months to what extent they just come back from root fragments I didn't get.

Reading some of the newer posts, it might be right for me to mention that I’m typically cutting back my true comfrey in the garden before they go to seed, so they don’t get to spread there. In the wild, they spread more. Before I knew comfrey, there was one in the forest that I would gaze in wonder at, but the plant died after a few years, probably a combination of competition (goutweed!) and shade. And now there is a patch in a lower section that I’m tending and cutting, and it has been a little happier since then, and there are descendent plants here and there from the seeds that came from the original patch.

Now, thinking about the soil benefits of comfrey and their dying in the forest, it seems like it might be a benefit to plant them under young trees. Peter Wohlleben mentions that trees that grow slowly, grow the strongest and healthiest wood, so maybe the competition from comfrey isn’t a terrible thing at first, as long as the tree is relatively tolerant of slow growth, like nut/forest trees. Maybe a little shade would help too, keeping the trees from drying out and overexposure.

I guess it’s more like an aframe vs a teepee. It currently has 3 bars but it may need a 4th. There was still some slight wilting last year but they were just planted then. I tied it together with fencing wire

I put it right up next to my apple trees. Big mistake. The other day my gopher-digger dog dug up a nest in the rootball of the 10-yr apple tree.
Some other trees are leaning over now, likely because the comfrey roots don't act as stable soil.

Do not plant it with the intention of it dynamic accumulating minerals, because sadly it doesn't really do any of that.

Henry Jabel wrote:Do not plant it with the intention of it dynamic accumulating minerals, because sadly it doesn't really do any of that.

Oooh, provocative! How do you know that? It certainly has long roots and builds a lot of biomass up top. Is it only pulling water up from the depths?

ETA: I went searching. There's not a lot, but the report over here says:

It is also possible that the widely reported benefits of mulching with Russian comfrey are not so much caused by its high nutrient content, but by other benefits resulting from mulching with plant tissue: increased organic matter, conservation of soil moisture, reduction in soil temperature, etc.

I do not grow comfrey but, after reading the posts about it, I googled it.

There is a plethora of information on the internet concern the plant. From what I have read, it is a great companion plant for organic gardening, attracts beneficial insects and those that prey upon destructive insects and enriches the soil. It should be planted in full sun, loamy, well-drained soil. It can be invasive due to its deep roots.

As I said above, while I do not current grown comfrey, it is a plant that will be giving serious consideration as to where to plant it in my vegetable garden.

Has anyone had experience using comfrey in pastures for ruminants?  

I'm curious if it would work well in clumps throughout my paddocks, and I imagine the animals would eat it down to the stalk.  So, might reduce the risk of spreading.  

Christopher Weeks wrote:

Henry Jabel wrote:Do not plant it with the intention of it dynamic accumulating minerals, because sadly it doesn't really do any of that.

Oooh, provocative! How do you know that? It certainly has long roots and builds a lot of biomass up top. Is it only pulling water up from the depths?

ETA: I went searching. There's not a lot, but the report over here says:

It is also possible that the widely reported benefits of mulching with Russian comfrey are not so much caused by its high nutrient content, but by other benefits resulting from mulching with plant tissue: increased organic matter, conservation of soil moisture, reduction in soil temperature, etc.

It does some minerals like all plants but its not particularly good at it. From the top of my head its average in calcium and that's about it. Dr Duke's Phytochemical database is the place to look.

That's minerals though if you are mulching with it you might also be spreading some useful biology around along with all the normal benefits of mulching.

It looks like there might be a valid claim to accumulating and distributing potassium and silicon, and boron to a lesser extent. And it does produce just an awful lot of foliage, so the gross physical reasons that chop-n-dropping anything is good, apply especially to comfrey even if dynamic accumulation isn't a legit reason.

Christopher Weeks wrote:It looks like there might be a valid claim to accumulating and distributing potassium and silicon, and boron to a lesser extent. And it does produce just an awful lot of foliage, so the gross physical reasons that chop-n-dropping anything is good, apply especially to comfrey even if dynamic accumulation isn't a legit reason.

Finally found the spreadsheet on the desktop:

K: Lambs quarter is 87100 vs Comfrey's 1870
Si: Horsetail 97000 vs Comfrey's 1
B: Dandelion 125 though there doesn't seem to much info on B

Cant seem to find a link to where I got this all in a handy spreadsheet and I cant seem to attach .xls sadly

Henry Jabel wrote:Do not plant it with the intention of it dynamic accumulating minerals, because sadly it doesn't really do any of that.

Can't speak for that, but I do know that the two most valuable benefits I have seen are weed impression around fruit trees, and the luscious organic rich soil that forms beneath it. The root zone of comfrey doesn't compete with the fruit trees, unlike grass. Where the comfrey is successfully suppressing the grass the fruit trees are doing far better.

Accumulation of minerals is always something I'm a little suspicious of anyway. Our chalk bedrock and subsoil is notoriously alkali, calcium rich, and deficient in certain minerals. They are present deeper in the chalk, but far beyond the root zone of any plants. If i want trace minerals I need to add them to the soil directly. My preference for this is granite rock dust.

I wonder how much the medicinal components are useful to the soil. All of the mucilage, for instance, has to provide some significant moistening effect, as well as other medicinal compounds perhaps affecting, nourishing and healing soil life/other plants. The leaves, and aeration, also might create a good microclimate, shaded and moist, for the proliferation of mycorrhizae. Perhaps these characteristics may still allow nutrients to become more available even if they aren’t present in the plant tissue.