Symphytum × uplandicum
Family Boraginaceae
Comfrey is the hardest-working plant in a food garden that you never eat: a deep-rooted fertility engine whose leaves regrow fast enough to cut several times a season for mulch, compost fuel, and traditional skin salves. Bees crowd its bloom while it quietly mines nutrients for everything nearby.
This is the sterile Russian hybrid, so it sets no seed and stays exactly where you put it instead of wandering the roadside. Fast, shade-tolerant, and 2-3 feet tall, it belongs under fruit trees and beside compost bins — choose its spot once, because those roots mean forever.
⚠ Spreads aggressivelyComfrey spreads vigorously and regrows from bits of root, so it's very hard to fully remove once established — give it a contained bed or a spot where it can roam freely, and edge it every year.
Full Sun to Shade
Moderate water
Very Fast growth
Salt-tolerant
Attracts bees
From the print shop
Our Plant Library collection carries comfrey — Symphytum uplandicum, print Nº 125, “Comfrey.”
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Hardy inZones 4-9Comfrey · Common problems
1 problem on file
None specific
1 problem on file
None specificComfrey · Comfrey strains
Garden comfrey is Russian comfrey (Symphytum × uplandicum), a sterile hybrid — it sets no seed, so unlike common comfrey it can't sow itself into a roadside weed. You increase it only by root cuttings or crown division.
In the 1950s Lawrence D. Hills — who went on to found the organic-gardening HDRA — trialed 21 comfrey strains at Bocking, Essex and numbered them Bocking 1–21. Only two are still grown today, and they split by job:
Pick your strain in the cultivar catalogue below.
Comfrey · Growing & propagation
LightWater
Soil
FertilizerUse urine or manure
PruningCut to ground for mulch ('Chop and Drop').
SpacingPropagateSterile, sets no seed
Comfrey · Seasonal care & spray guidance
early spring
3 jobsFeedingIn springSoil test before planting and work the fertilizer into the top 6 inches. On an established patch, apply roughly 1 to 2 teaspoons of 21-0-0 per square foot per month through the growing season. Comfrey is not a legume and cannot fix its own nitrogen, and you carry the entire leaf mass off the plant several times a year. Every cutting exports nitrogen the plant has to replace before it can push the next flush.
DividingIn springComfrey can go in any time from April to September, but it establishes best in spring. Lay root cuttings flat 2 to 4 inches deep, putting the longer pieces deeper, and set crown divisions or transplants upright about 2 inches deep. Space rows 2 to 3 feet apart in a checkerboard, tightening the spacing if you want more leaf per square foot. Comfrey rarely produces seed, so cuttings and divisions are the only practical way to increase it. Root cuttings take 3 to 6 weeks to push buds while crown divisions break ground in about 10 days, which is why divisions are the choice when you want leaf the same year.
What to watch forIn springEach spring, look for shoots coming up outside the bed you planted, especially anywhere you dug or moved soil last year. Lift young strays whole while the root is still shallow. Control weeds in the patch by shallow cultivation only, and avoid damaging comfrey roots, which sets the plant back. Comfrey is propagated from root cuttings precisely because root pieces develop buds and grow on, so soil-moving work around a patch tends to spread it rather than remove it. Utah State Extension warns comfrey can become invasive if it is not contained or controlled, which is why it is worth checking the edges once a year while strays are still small.
the growing season
1 jobWateringIn summerCheck the soil between cuttings and water once the top 2 inches are noticeably dry. Aim for moderate, steady moisture rather than letting the patch swing between soaked and bone dry. The roots run deep enough that comfrey rides out drought, but it still prefers moderate soil moisture, and the leafy regrowth you are asking for after each cut is mostly water.
as it ripens, and picking
1 job
HarvestingAt harvestLeave the plant alone the first year and start cutting in year two. Once established, gather a bunch of leaves and cut about 2 inches above the ground every 2 weeks through the growing season. If you want root as well, dig from one side of the root system only so the plant carries on. Cutting low and often keeps the crown pushing fresh leaf instead of running to flower, and the first season is what the plant needs to build the deep root that funds every later cut.
Comfrey · Companion plants
Good companions
Underlined names have their own growing guide in this library.
Comfrey · Calculators & field guides
Comfrey · Yearly calendar
PruneJanuary to December
BloomPruneHarvestBloomMarch to August
PruneJanuary to December
HarvestMay to September
These are the species' typical months — expect them a few weeks earlier in warm zones and later in cold ones. Watch the plant, not just the calendar.
Comfrey · Ecology & uses
Symphytum × uplandicum
AttractsMoisture
SaltFine near roads and coasts
DeerProtect young plants
Origin! Some parts toxic — see notesNever take internally — pyrrolizidine alkaloids cause sinusoidal obstruction syndrome and severe liver injury (FDA asked manufacturers to remove oral comfrey supplements in 2001). Topical use only, on intact skin, in short courses (EMA: about 10 days; Germany caps 4-6 weeks a year). Avoid in pregnancy and breastfeeding, and use caution on children.
UseUseTraditional use
Traditional use ratingCut 3-4 times/season.
Edibility, identification, and traditional-use notes here are general reference — not medical or veterinary advice, and not a claim that any plant treats or prevents anything. Medicinal ratings record how strongly a plant features in herbal tradition, nothing more. Never eat or dose a plant you have not positively identified. More on how to use this library.
Comfrey · Varieties & cultivars
Comfrey's named strains are the Bocking series — sterile Russian comfrey (Symphytum × uplandicum) selections bred by Lawrence D. Hills at Bocking, Essex in the 1950s and numbered from his trial plots. Sterile selections such as Bocking 14 do not produce viable seed: multiply them by root cuttings or crown division. They do not self-seed, but pieces of root left in the soil can regrow. Bocking 14 is the one most gardeners want: rust-resistant, the highest in potassium, with a deep taproot that mines minerals for chop-and-drop fertilizer. Bocking 4 is the beefier forage strain.
Which type are you growing? Non-sterile common comfrey (Symphytum officinale) can also grow from seed; seed-grown common comfrey is not Bocking 14. Non-sterile comfrey can spread invasively by seed and is hard to remove once established; root fragments can regrow. Follow the root-cutting guide.
2 varieties
The garden standard and the strain you'll usually find. Sterile — sets no seed — with the highest potassium of any comfrey (~7% potash) and the top rust resistance. Its thin flower stems break down fast, so it's the pick for chop-and-drop mulch, compost activation, and 'comfrey tea'. Slightly higher pyrrolizidine alkaloids than Bocking 4, so keep it out of the kitchen and off livestock feed.
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The forage strain: deeper-rooted and more drought-hardy, with more protein and lower pyrrolizidine alkaloids — the safer pick where it'll be grazed or eaten. Also sterile. Choose Bocking 4 for animal fodder; choose Bocking 14 for feeding the soil.
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Sources & plant identity
Symphytum × uplandicum
Hardiness, size and timing vary with your cultivar, soil and climate.
University extension research, brought together with hands-on growing experience at Story Thyme Farms.
Publisher marks identify sources, not sponsorship or endorsement.
Comfrey questions, answered straight.
With care. Never take internally — pyrrolizidine alkaloids cause sinusoidal obstruction syndrome and severe liver injury (FDA asked manufacturers to remove oral comfrey supplements in 2001). Topical use only, on intact skin, in short courses (EMA: about 10 days; Germany caps 4-6 weeks a year). Avoid in pregnancy and breastfeeding, and use caution on children. Site it accordingly if children or pets roam the garden. This is general reference, not medical or veterinary advice — call a vet or poison control if something has actually been eaten.
Cut 3-4 times/season.
Proven companions include fruit trees (chop-and-drop mulch under them) — the full companion list, and what to keep away, is in the Growing tab above.
Root cuttings or crown division only — sterile, sets no seed.
It can be an aggressive spreader — give it room or a barrier, and check your state's invasive-species list before planting.
Where comfrey sits in the library.
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