Illustration
Russian Comfrey
Symphytum × uplandicum
Also called bocking 14
Russian Comfrey blooms from May through June.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Russian Comfrey
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 4–8. Expect it to reach about 3.5 ft tall and 2.5 ft wide at maturity, in roughly 2 years (a house reading).
Is Russian Comfrey toxic to dogs or cats?
- Listed as toxic to dogs and cats by Extension Toxicology Network, Oregon State University.
- Listed as poisonous to people by Royal Horticultural Society.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Fifteen fields were checked against named botanical sources, each recorded beside the sources that carried it, with every unsettled point written down and decided: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, soil, diseases, pests, toxicity, the plant's own names, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Russian Comfrey
Plant Russian Comfrey in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 4 to 8, spring means March to May and fall means August or September. Once settled, it blooms from May to June.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Russian Comfrey get?
3.5 fttall5 ft 7 inan adult2.5 ftwideSee Russian Comfrey in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Russian Comfrey
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Russian Comfrey about 2.5 ft apart, center to center, so each plant has room to reach its full width.
Add Russian Comfrey to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Russian Comfrey's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 9 published sources on August 28, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity
- RHSRoyal Horticultural Societyheight, spread, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity
- Plants For A Futureheight, spread, water, bloom months and color, soil, diseases and toxicity
- mountainvalleygrowers.comMountain Valley Growersheight, hardiness zones, sun, bloom months and color, pests and toxicity
- NC State ExtensionPlant Toolboxsun, bloom months and color, diseases, pests and toxicity
- strictlymedicinalseeds.comStrictly Medicinal Seedsspread, hardiness zones and toxicity
- blog-fruit-vegetable-ipm.extension.umn.eduUniversity of Minnesota Extensionsun
- ftc.govUS Federal Trade Commissiontoxicity
- ncbi.nlm.nih.govNIH LiverTox (NCBI Bookshelf)toxicity
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Russian Comfrey
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Leaves and roots carry pyrrolizidine alkaloids. Swallowed, they can cause sinusoidal obstruction syndrome and severe liver injury, and the harm accumulates rather than showing at once. The FDA asked US suppliers to withdraw comfrey products meant to be taken by mouth in 2001. Horses and cattle are at real risk too, and dried comfrey in hay stays toxic while becoming more palatable. Growing it, cutting it, composting it and using it as a mulch or liquid feed are all ordinary and fine; eating it, brewing it as tea, or letting a horse reach it are not. per NIH LiverTox and FDA and Oregon State
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.