Seven pretty detailed questions about comfrey

Hello All,

First year home owner, gardner, composter, and first year I've ever kept a plant alive for longer than a few weeks! I've always liked the idea of growing my own food and permaculture but never really had a reason to start researching until now. It became readily apparent how useful comfrey (bocking 14) is and it's one of the first additions to my property. I've read A LOT about it but I do have some remaining questions for those of you with more knowledge than I. If you dont mind filling in some gaps for me or offering some other information it would be so greatly appreciated! I am located in Minnesota.


1: Can you use comfrey concentrate for lawn care? The lawn at this new house is in serious decline and while I plan to aerate and re sead this fall, I was wondering if it would work to dilute it to the same 15:1 ratio and spray it on the lawn. How often should I do it if it would benefit from it?

2: Will comfrey benefit regular trees (deciduous or coniferous) or just fruit trees? I have some colorado blue spruce with a fungus and some other trees in back that are in decline and I would like to save them if possible. All I can find online is using comfrey with fruit trees but wasn't sure if other trees would benefit?

3: Are there any vegetables or plants in which I should not mulch with comfrey leaves or use the diluted concentrate for a foliar spray? I've read that some vegetable plants don't do too well with higher levels of nitrogen (like lettuce?) but wasn't sure if it makes a difference between organic products like comfrey or if it is more so for commercial fertilizers. How often should I use the diluted concentrate in the garden?

4: I've read mixed reviews about how much sun these plants like and calling for everything from full sun to mostly shade. Any input from you guys?

5: How much water do these things like? I've read they grow well around creeks or rivers, does this mean they need a lot of water? If so, that may play a role in determining where the comfrey patch will go. I've been watering these planters a little each day.

5: In the last few weeks I have acquired from friends and an online retailer a total of 6 root cuttings that are starting in some small planters, 8 small plants (about 1yr old) in 5 gallon buckets, and 4 large plants (3yrs old with about a 14" rootball) in some 10 gallon planters. I understand that planters are not the greatest for these due to their wanting to send deep roots. My problem is almost the entire back yard will soon be cleared of buckthorn, tore up, regraded a bit or worked in some manner or another here soon and I wasn't sure where the final resting place for these will be yet and I didn't want to accidentally spread the roots where I don't want them. I am hoping to keep them alive long enough (1-2 months) to place in the ground. Is this wishful thinking? I have them in a mix of 66% compost and 34% potting mix mulched on top with straw.

6: I have one spot along the back of the house where I think I can put the large comfrey plants to get them in the ground, my only hesitation is that we may end up adding 1-2' tall retaining wall (raised bed) there and raising that ground up. If I plant them now at ground level and we then decide we need or want to add the retaining wall, would the comfrey still grow up and through that additional ground?

7: There is one spot in the yard which wont be worked over much due to a nice cluster of some really large cottonwood trees (see picture). I've seen a lot of people plant hostas around tree bases but was thinking about using comfrey instead however I am not sure how to go about it. I've read the benefits of planting comfrey in fertile holes and filling them with chicken manure, compost, etc. but I am afraid of hitting or damaging some of the cottonwood roots. I've thought about building up the tree base area with soil and compost and then planting the comfrey but I've also read that you shouldn't add anything around tree bases except mulch or it will damage or kill the tree (is this true?) Any thoughts about how to do this, I think it would look really nice. Also, how far should I plant them around the tree bases, 3'?

Robb Olson wrote:
2: Will comfrey benefit regular trees (deciduous or coniferous) or just fruit trees? I have some colorado blue spruce with a fungus and some other trees in back that are in decline and I would like to save them if possible. All I can find online is using comfrey with fruit trees but wasn't sure if other trees would benefit?

I use the leaves to mulch everything.  Biomass is biomass, unless it it aleopathic, which comfrey most certainly isn't.  Blue Spruce can get infestations of yellow headed spruce saw fly, rust, spider mites . . . all sorts of things.  While a heavy mulch of comfrey will feed the roots and the soil around the tree, I don't think it will do anything to take care of pests or diseases once the tree has them.

Robb Olson wrote:
4: I've read mixed reviews about how much sun these plants like and calling for everything from full sun to mostly shade. Any input from you guys?
5: How much water do these things like? I've read they grow well around creeks or rivers, does this mean they need a lot of water? If so, that may play a role in determining where the comfrey patch will go. I've been watering these planters a little each day.

Both.  I've got it growing in full Southern California sun, as well as under fruit trees in the integrated orchard.  It does well wherever.  When it's thirsty, you'll see it wilt.  Because I grow comfrey pretty much throughout my food forest, it gets watered with everything else.  On a hot sunny day, like many broad leaf plants, you'll see it wilt.  But it usually perks right back up when the sun goes down.  Once established, it does much better when things get dry.

Robb Olson wrote:
5: In the last few weeks I have acquired from friends and an online retailer a total of 6 root cuttings that are starting in some small planters, 8 small plants (about 1yr old) in 5 gallon buckets, and 4 large plants (3yrs old with about a 14" rootball) in some 10 gallon planters. I understand that planters are not the greatest for these due to their wanting to send deep roots. My problem is almost the entire back yard will soon be cleared of buckthorn, tore up, regraded a bit or worked in some manner or another here soon and I wasn't sure where the final resting place for these will be yet and I didn't want to accidentally spread the roots where I don't want them. I am hoping to keep them alive long enough (1-2 months) to place in the ground. Is this wishful thinking? I have them in a mix of 66% compost and 34% potting mix mulched on top with straw.

I've kept comfrey in 5 gal. pots for 6 months or more.  You'll need to water it daily, as it will quickly fill the pot with roots and add a ton of biomass (leaves) above ground.  Yes, you're right about not wanting a plant in the wrong location, so a word of warning: you'll quickly find that the roots go through any hole in the bottom of your pot, and the plant will start to root right there where the pot is standing.  Short of setting the pot on concrete, be prepared to find that your potted comfrey will find its way into the ground.  Quickly.

Here is how you can tell that it's rooting in the ground: while other potted comfrey wilt in the hot sun, the ones that have tapped down into the soil will be perky and strong.  I've got a comfrey plant in a spot where a pot once sat.  When I picked the pot up, the grounded root snapped off, and then quickly established itself as a new plant within a couple of weeks.

Robb Olson wrote:

6: I have one spot along the back of the house where I think I can put the large comfrey plants to get them in the ground, my only hesitation is that we may end up adding 1-2' tall retaining wall (raised bed) there and raising that ground up. If I plant them now at ground level and we then decide we need or want to add the retaining wall, would the comfrey still grow up and through that additional ground?

It might come up through that much soil.  They aren't known for pushing up through soil as much as they are known for punching down through soil.

You can kill a comfrey plant a couple of ways -- but not easily.  1.  You can build a hot compost pile on top of it, but from the sounds of things, that location may not work for a 4 foot by 4 foot by 4 foot pile.  2.  You can hit it with an herbicide.  I didn't say that.  Look out -- here come the organic police to lock me up.  3.  My preferred method of ridding myself of an unwanted (poorly located) comfrey plant is to first dig as much of the rootball out, and then cover what remains with a black tub or pot.  I've got a bunch of old 15 gallon pots from various fruit trees I've purchased over the years.  I cover the holes in the bottom of the pot with duct tape, and then I just put the pot upside down over the comfrey plant.  I'll kick a bit of mulch around the outsides of the pot to keep any sunlight from getting in, and then i leave it.  For a LONG TIME.  That usually kills the plant.

Robb Olson wrote:
7: There is one spot in the yard which wont be worked over much due to a nice cluster of some really large cottonwood trees (see picture). I've seen a lot of people plant hostas around tree bases but was thinking about using comfrey instead however I am not sure how to go about it. I've read the benefits of planting comfrey in fertile holes and filling them with chicken manure, compost, etc. but I am afraid of hitting or damaging some of the cottonwood roots. I've thought about building up the tree base area with soil and compost and then planting the comfrey but I've also read that you shouldn't add anything around tree bases except mulch or it will damage or kill the tree (is this true?) Any thoughts about how to do this, I think it would look really nice. Also, how far should I plant them around the tree bases, 3'?

Sure -- 3 feet.  Or a bit farther.

Honestly, I don't think you have to be too fussy about planting your comfrey in perfectly prepared holes.  It does pretty well regardless.  Of course, yes, the better the soil you plant it in, the quicker it will establish itself, but I wouldn't over think it.  Scratch around a bit and find a spot without a big root, plant your comfrey root cutting, push the soil back into place, and then lay a heavy mulch layer down.  Done.  Just water it regularly until it is established.

Cottonwood trees are tough suckers.  I don't know of anyone who has killed one by messing with their roots.  In fact, aren't cottonwood roots quite invasive (sewer line cloggers)?  

If you want to be careful of the roots, then carefully dig down.  Maybe flush the hole with a hose regularly so that you wash the soil back away from the roots.  But a well established tree isn't going to die if you poke a couple of little holes in the ground for a 3 or 4 inch comfrey root.

Best of luck.

One other thought: if you want to plant your comfrey near a tree but are worried about digging a hole, then that's where you'll want to keep your potted plants until you are ready to move them and plant them elsewhere.  Make that your comfrey nursery.  As the pots sit in one location, the plants will sink their roots through the holes in the bottom of the pot and will establish themselves in that spot.

Then, when you are ready to plant them elsewhere, you'll need to break the plant away from that spot.  The root will snap right off.

Now you'll get two plants from one pot.  Bada bing, and away you go.

I would only add:

6.  I doubt the comfrey would push up thru a foot or two of soil.  It's very easy to dig it up and move it before adding the retaining wall and dirt, and I would certainly do that.

The nice thing about comfrey is that you can set it and forget it.  It is dead simple.  Eventually you will forget that it's out there just doing it's little job of feeding bees and covering ground.   Make sure you like where you're planting it, stick a chunk in the ground, sort of make sure it gets established, then just let it do its thing.  The first couple of years, I chopped and dropped mine, but left it alone this year and it got massive.  It's doing a great job of living mulch all on its own and makes a nice garden plant if you let it do its own thing.

I don't think comfrey is likely to save an ailing tree.  I lost a nice young plum tree this spring to too much rain and likely a fungus.  It was underplanted with comfrey.  The good news is the comfrey is still there, being pretty.  So, while it makes great mulch, I would not rely on it to solve a big problem.

Young plants will wilt when they don't have enough water but have no problem springing back up.  In a dry climate, I'd probably be a little more careful about where I planted them, but mine have to survive on their own. Which, granted, is in a maritime climate so spring and fall they have all the water they need.  But, in summer, they're on their own.  '

The hole you need to dig for comfrey is so small, I wouldn't worry at all about hurting cottonwoods.  If you feel you're near a root, move to the side and try again.

Thanks for the help! So these plants, once fully established, will be roughly 3' diameter from what I have read, is this correct? I will space them out a little farther per your suggestion just so it wont feel so crowded. I would like the comfrey around the towering cottonwoods to be both ornamental as well as functional, similar to the attached hosta photos but with comfrey. How far away from the tree trunks/bases should they be (24" from base to center of comfrey plant?)? I've seen some hosta's that are pretty close to the base of trees so was just wondering what would be best. I hope you don't mine but I am calling upon your inner plant artistry here,  should I plant anything else around the trees with the comfrey that would either enhance the look or be beneficial (like clover or not sure what else, still new to plants)? My overall goal for the backyard would be to look like a woodland garden and since this cluster of cottonwoods are pretty much the focal point of the little basin area, I would like it look lively and full. Thank you again for your time to answer my questions!!

Robb

Robb Olson wrote:
6: I have one spot along the back of the house where I think I can put the large comfrey plants to get them in the ground, my only hesitation is that we may end up adding 1-2' tall retaining wall (raised bed) there and raising that ground up. If I plant them now at ground level and we then decide we need or want to add the retaining wall, would the comfrey still grow up and through that additional ground?

Ok, the other responses imply that you wouldn't want the comfrey in the raised ground.  It could be that I'm a comfrey fan or maybe a little slow in the head, but I was thinking you meant that you did want it.  When you say "hesitation", I thought you meant that you want comfrey plants now but you don't want to lose them, and you're not sure if the plants would remain when you raise the ground (without digging and replanting and disrupting their roots).
No, I don't know the answer to that question, but I would be curious if someone did that experiment.  I think they might go through 1' of dirt, am not sure about 2'.

I saw this video and thought it should be in here.

Good going guys,

Eric