Comfrey is a perennial medicinal herb, long valued for its traditional uses. Notably, it stands up to deer. Its summer flowers are a real draw for honeybees and native bees.
Zones
Data not available
pH Range
5.5-8
Sun
Part Sun
Days to Maturity
85
Score Comfrey on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether comfrey actually takes — and those shift from one yard to the next. Enter your address and we'll score comfrey against your land's real conditions.
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What Comfrey is
Comfrey grows as a perennial and reaches around three feet at maturity. It blooms purple in summer. It's also deer-resistant.
How to grow Comfrey
Comfrey is ready to harvest about 85 days after planting. Comfrey does best in part sun — at least 4 hours of direct sun a day — and soil from pH 5.5 to 8, on well-drained ground. It needs around 1,800 growing degree days to mature and a growing season of at least 90 frost-free days, which is why climate matters as much as soil.
USDA Zones
Data not available
USDA PHZM 2023
Soil pH
5.5 - 8
USDA PLANTS Database
Sun
Part Sun
plant_species_v5.csv
Drainage
well (dry spells)
plant_species_v5.csv
Days to Maturity
85 days
Comfrey; perennial; propagated by root division (not seed). Cut for mulch / chop-and-drop.
USDA-NRCS
GDD Required
1800+
plant_species_v5.csv
Mature Height
3 ft
plant_species_v5.csv
Frost-Free Days
90+
plant_species_v5.csv
Start the season right
Plant comfrey in part sun with at least 4 hours of direct sun, once the soil has warmed and frost risk has passed.
Match the soil
Comfrey prefers pH 5.5 to 8 (USDA PLANTS Database). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band.
Water steadily
Keep the root zone evenly moist through establishment. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at its peak
Harvest the part you grow comfrey for — flower, leaf, or root — at its seasonal peak.
Good to know
One caution for pet owners — comfrey is toxic to dogs and cats (moderate severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Comfrey is a standout pollinator plant — high value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)
Where Comfrey thrives
Whether comfrey thrives on a given site comes down to its soil pH, drainage, sun, and frost dates — the conditions that vary parcel to parcel.
See if Comfrey will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether comfrey actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Frequently Asked Questions
Can I grow Comfrey in my zone?
Zone data for comfrey is being finalized. A Growable Ground report checks your parcel's full suitability against federal soil, climate, and zone data.
How long does Comfrey take to grow?
Comfrey is ready to harvest about 85 days after planting (USDA-NRCS). Your local frost dates and soil temperature move that window earlier or later.
When should you plant Comfrey?
Most growers plant comfrey after the last spring frost, once the soil has warmed, leaving enough of the season for its 90-day frost-free need. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Comfrey need?
Comfrey does well in partial sun — around 4 hours of direct sun, and it takes some afternoon shade in stride. That flexibility makes it a good match for a bed the house or a nearby tree shades for part of the day. A Growable Ground report maps how the sun actually falls on your land, hour by hour, so you can set it where the light lines up.
What soil does Comfrey need?
Comfrey prefers soil pH 5.5 to 8, on well-drained ground (USDA PLANTS Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Comfrey attract pollinators?
Yes — comfrey's flowers are a strong nectar and pollen source for honeybees and native bees (Xerces Society, Pollinator Partnership).
Is Comfrey safe for pets?
Comfrey is toxic to pets (dogs,cats) with moderate severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency.