St Johns Wort is a perennial medicinal herb, long valued for its traditional uses. It's hardy across USDA zones 3 through 8, 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.
St Johns Wort — the short answer
St Johns Wort: grown in zones 3–8, full sun, pH 5–8, about 120 days to maturity.
- USDA zones
- 3–8
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Soil pH
- 5–8
- Growable Ground Plant Database
- Sun
- Full Sun
- Growable Ground Plant Database
- Days to Maturity
- 120 days
- Growable Ground Plant Database
- Frost-kill temperature
- -30°F
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — each tile names its own row's source, because per-field provenance varies.
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 grows in USDA zones 3 through 8 and 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
3-8
USDA PHZM 2023
Soil pH
5 - 8
Growable Ground Plant Database
Sun
Full Sun
Growable Ground plant catalog
Drainage
well (dry spells)
Growable Ground plant catalog
Frost Kill Temperature
-30°F
Where cold starts killing growing tissue. Not a winter-survival floor — a dormant perennial takes far colder, which its hardiness zone answers.
Growable Ground Plant Database
Days to Maturity
120 days
Growable Ground plant catalog
GDD Required
700+
Growing degree-days of accumulated warmth it needs to mature — humid summers reach this faster than cool coastal ones.
Growable Ground plant catalog
Mature Height
3 ft
Growable Ground plant catalog
Frost-Free Days
0+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
Start the season right
Plant st johns wort in full sun with at least 6 hours of direct sun. It grows in the cool halves of the year, so sow it in spring or late summer rather than waiting for midsummer heat.
Match the soil
St Johns Wort prefers pH 5 to 8 (Growable Ground Plant 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.
Where St Johns Wort thrives
St Johns Wort is hardy across USDA zones 3 through 8. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 3–8 spans average winter lows from -40°F to 20°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 34 outright and splits 17 more down the middle — and which side of that line your land sits on changes the answer.
Zones 3–8·Where St Johns Wort growsOpen map →
Where St Johns Wort stands, state by state
St Johns Wort is rated for zones 3–8 — a cold floor USDA puts at -40 to -30°F. Across the 50 states and DC, 34 sit fully inside that band, the line runs through 17 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 3–8
34 states
3 of 34 shown
The line runs through
17 states
- Alaska · zones 1a-9a
- California · zones 4b-11a
- Nevada · zones 4a-10a
3 of 17 shown
St Johns Wort’s band covers part of each of these states — which side of the line your county sits on changes the answer, and each state page draws it.
State zone extents: USDA Plant Hardiness Zone Map (PHZM) 2023. A zone is a 10°F band of average annual extreme minimum temperature, so a state that splits the band contains the boundary — its own page draws the county line, and a parcel report resolves which side your land sits on.
What grows around St Johns Wort
Growing guides for st johns wort
In rotation planning, st johns wort counts as a Other — beds recover best when other crops don’t follow each other in the same spot year over year. (Growable Ground derivation — crop-rotation group from botanical family)
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.
Before you harvest st johns wort, know your soil
Anything you grow to eat takes up what's in the ground it grows in, so it's worth knowing what's documented near you before you plant st johns wort for food. Our free screen reads 9 federal source types across roughly 1.8M indexed sites and shows which sit near your address and which way they drain. It's a screening estimate from public records and proximity — not a soil test — so a nearby record means a soil test is worth it, not that your soil is unsafe.
Your land is one point inside St Johns Wort's range
This page resolves to the species. Your state page draws the county line, and a report reads the parcel — the soil pH, drainage, sun, and frost dates on your exact ground, which no species average can see.
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:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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How we know this about St Johns Wort
The figures above are cited per row, not per site: the pH band names this plant’s own source column, the three temperature figures each carry their own, and days-to-maturity cites the publication that actually lists it. All of it comes from the Growable Ground Plant Database — a compilation over FAO ECOCROP, USDA PLANTS, and university Extension sources, published openly with per-field provenance.
Grounded inUSDA PLANTS Database•USDA PHZM•ASPCA
Frequently asked questions
Can I grow St Johns Wort in my zone?
St Johns Wort grows in USDA hardiness zones 3 through 8 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
How long does St Johns Wort take to grow?
St Johns Wort is ready to harvest about 120 days after planting. Your local frost dates and soil temperature move that window earlier or later.
When should you plant St Johns Wort?
St Johns Wort is a cool-season crop, so it goes in during the cool halves of the year — early spring, and again in late summer for a fall planting — rather than at the height of summer heat. 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 (Growable Ground Plant 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.
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. (Source: ASPCA.)