St Johns Wort is a perennial medicinal herb, long valued for its traditional uses. Notably, it stands up to deer and grows just as well in a container as in the ground. Its summer flowers are a moderate draw for honeybees and native bees.
Zones
Data not available
pH Range
5-8
Sun
Full Sun
Days to Maturity
120
Score St Johns Wort on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether st johns wort actually takes — and those shift from one yard to the next. Enter your address and we'll score st johns wort against your land's real conditions.
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What St Johns Wort is
St Johns Wort grows as a perennial and reaches around three feet at maturity. It blooms yellow in summer. It's also deer-resistant and well suited to containers.
How to grow St Johns Wort
St Johns Wort is ready to harvest about 120 days after planting. St Johns Wort does best in full sun — at least 6 hours of direct sun a day — and soil from pH 5 to 8, on well-drained ground. It needs around 700 growing degree days to mature, which is why climate matters as much as soil.
USDA Zones
Data not available
USDA PHZM 2023
Soil pH
5 - 8
USDA PLANTS Database
Sun
Full Sun
plant_species_v5.csv
Drainage
well (dry spells)
plant_species_v5.csv
Days to Maturity
120 days
plant_species_v5.csv
GDD Required
700+
plant_species_v5.csv
Mature Height
3 ft
plant_species_v5.csv
Frost-Free Days
0+
plant_species_v5.csv
Start the season right
Plant st johns wort in full sun with at least 6 hours of direct sun, once the soil has warmed and frost risk has passed.
Match the soil
St Johns Wort prefers pH 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 st johns wort for — flower, leaf, or root — at its seasonal peak.
Good to know
One caution for pet owners — st johns wort 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.)
St Johns Wort offers moderate value to bees and other pollinators. (Source: Xerces Society, Pollinator Partnership.)
Where St Johns Wort thrives
Whether st johns wort 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 St Johns Wort will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether st johns wort actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
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Frequently Asked Questions
Can I grow St Johns Wort in my zone?
Zone data for st johns wort is being finalized. A Growable Ground report checks your parcel's full suitability against federal soil, climate, and zone data.
How long does St Johns Wort take to grow?
St Johns Wort is ready to harvest about 120 days after planting (University Extension production guides). Your local frost dates and soil temperature move that window earlier or later.
When should you plant St Johns Wort?
Most growers plant st johns wort after the last spring frost, once the soil has warmed. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does St Johns Wort need?
St Johns Wort needs full sun — a spot that catches at least 6 hours of direct summer sun a day. In more shade it still grows, but usually gives a smaller, later crop. The catch is that a yard rarely gets even light everywhere — a fence, the house, or one tall tree can quietly take those hours. A Growable Ground report reads the real sun-hours across your land, canopy and buildings included, so you can pick the brightest bed before you plant.
What soil does St Johns Wort need?
St Johns Wort prefers soil pH 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 St Johns Wort attract pollinators?
Yes — st johns wort's flowers are a solid nectar source for honeybees and native bees (Xerces Society, Pollinator Partnership).
Is St Johns Wort safe for pets?
St Johns Wort 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.