Skullcap is a perennial medicinal herb, long valued for its traditional uses. It's hardy across USDA zones 3 through 9, stands up to deer and grows just as well in a container as in the ground. Its summer flowers are a moderate draw for native bees and butterflies.
Skullcap — the short answer
Skullcap: grown in zones 3–9, full sun, pH 5.5–7.5, about 120 days to maturity.
- USDA zones
- 3–9
- 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
- 5.5–7.5
- 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 Skullcap on your exact land.
Zone averages can't see the slope, soil, frost, and sun that decide whether skullcap actually takes — and those shift from one yard to the next. Enter your address and we'll score skullcap against your land's real conditions.
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What Skullcap is
Skullcap grows as a perennial and reaches around two feet at maturity. It blooms blue in summer. It's also deer-resistant and well suited to containers.
How to grow Skullcap
Skullcap grows in USDA zones 3 through 9 and is ready to harvest about 120 days after planting. Skullcap does best in full sun — at least 6 hours of direct sun a day — and soil from pH 5.5 to 7.5, on consistently moist ground. It needs around 1,200 growing degree days to mature and a growing season of at least 100 frost-free days, which is why climate matters as much as soil.
USDA Zones
3-9
USDA PHZM 2023
Soil pH
5.5 - 7.5
Growable Ground Plant Database
Sun
Full Sun
Growable Ground plant catalog
Drainage
poorly (saturated >50% of year)
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
1200+
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
2 ft
Growable Ground plant catalog
Frost-Free Days
100+
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 skullcap 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
Skullcap prefers pH 5.5 to 7.5 (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. Match watering to the plant's drainage preference and your local rainfall.
Harvest at its peak
Harvest the part you grow skullcap for — flower, leaf, or root — at its seasonal peak.
Where Skullcap thrives
Skullcap is hardy across USDA zones 3 through 9. 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 3–9 spans average winter lows from -40°F to 30°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 42 outright and splits 9 more down the middle — and which side of that line your land sits on changes the answer.
Zones 3–9·Where Skullcap growsOpen map →
Where Skullcap stands, state by state
Skullcap is rated for zones 3–9 — a cold floor USDA puts at -40 to -30°F. Across the 50 states and DC, 42 sit fully inside that band, the line runs through 9 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 3–9
42 states
3 of 42 shown
The line runs through
9 states
- Alaska · zones 1a-9a
- California · zones 4b-11a
- Nevada · zones 4a-10a
3 of 9 shown
Skullcap’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 Skullcap
Growing guides for skullcap
In rotation planning, skullcap 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
Good news for pet owners — skullcap isn't known to be toxic to dogs or cats. (Source: ASPCA.)
Skullcap offers moderate value to bees and other pollinators. (Source: Lady Bird Johnson Wildflower Center.)
Before you harvest skullcap, 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 skullcap 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 Skullcap'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 Skullcap will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether skullcap 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 Skullcap
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 Skullcap in my zone?
Skullcap grows in USDA hardiness zones 3 through 9 (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 Skullcap take to grow?
Skullcap 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 Skullcap?
Skullcap 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 Skullcap need?
Skullcap 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 Skullcap need?
Skullcap prefers soil pH 5.5 to 7.5, on consistently moist ground (Growable Ground Plant Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Skullcap attract pollinators?
Yes — skullcap's flowers are a solid nectar source for native bees and butterflies. (Source: Lady Bird Johnson Wildflower Center.)
Is Skullcap safe for pets?
Skullcap is not known to be toxic to dogs or cats based on available data. Always supervise pets around new plantings. (Source: ASPCA.)