woodland wildflower

Great St. John's Wort

Hypericum ascyron

Also known as Great St. John's-wort, Giant St. John's-wort, great St. Johnswort

Native to the Midwest and the Northeast and southern Canada

Quebec to Minnesota, south to New Jersey, Pennsylvania, Indiana, southwestern Iowa and northeastern Kansas

Light Full sun to shade Sun tolerance
Moisture Moist to wet Moisture preference
Zones 3–7 Cold to heat range
Bloom Jun–Aug Flowering time
Height up to 6 ft to 1.8 m
Life cycle Perennial Annual to perennial

Full details, see below

In the garden

A woodland wildflower for sun through shade and consistently moist to wet soil. At up to 6 ft, it needs room in shade gardens and woodland edges. Hardy in USDA zones 3–7.

Growing conditions

Light

Full sun Partial shade Full shade

Moisture

Dry Moist Wet

Hardiness zones

Find your zone:

Pollinators & wildlife

Bees Common Eastern Bumble Bee

also Brown-belted Bumble Bee, American Bumble Bee, Ligated Furrow Bee +7 more
Half-black Bumble Bee, Worthy Longhorn, Ceratina dupla, Illinois Cuckoo Sweat Bee, Colourful Willow Miner Bee, Yellow-spotted Cuckoo Nomad Bee, Colletes productus
Flower flies Eastern Hornet Fly

also Hairy-eyed Bee-mimic Fly, Yellow-throated Meadow Fly, Yellow-legged Bog Fly +1 more
White-haired Pithead
Beetles Mordellistena comata also Metacmaeops vittata
Also visited by
- Wasps: Ancistrocerus tigris

Full plant details

Where it grows

Habitat: WoodlandThe wild plant community it grows in.
Native range: The Midwest and the Northeast and southern CanadaUnited States (18): CT, IA, IL, IN, KS, MA, ME, MI, MN, MO, NE, NH, NJ, NY, OH, PA, VT, WI. Canada (2): ON, QC. Where it grows wild on its own, by state and province.
Native distribution: Quebec to Minnesota, south to New Jersey, Pennsylvania, Indiana, southwestern Iowa and northeastern KansasThe same native range, usually more exact than the state list, and often noting where it has spread beyond it.

Growing conditions

Light: Full sun to shadeHow much sun it takes, from full sun to full shade.
Moisture: Moist to wetThe soil dampness it prefers, from dry to wet.
Hardiness zones: USDA 3–7 · Canadian 4–7The cold-to-heat climate range it survives.
Soil: Moist soilsThe soils it grows in naturally.
Soil texture: Light to heavy (sandy to clay)The soil grade it prefers, from sand to clay.
Soil pH: 5.7–7.1The acidity to alkalinity it tolerates (7 is neutral).
Soil quality: MediumHow rich a soil it needs. Many natives prefer lean soil and flop in rich beds.
Water use: MediumHow thirsty it is, a rough guide to how often to water.
Salinity tolerance: NoneHow well it copes with salty soil, near roads or the coast.
Lime (CaCO₃) tolerance: LowHow well it copes with chalky, lime-rich soil.

Growth & form

Height: up to 6 ft (to 1.8 m)Typical mature height.
Life cycle: PerennialWhether it lives a single season (annual), two (biennial), or returns for years (perennial).
Growth rate: ModerateA relative ranking versus other plants of the same type (USDA), not an absolute rate.
Shape: ErectIts overall silhouette.
Root depth: 14+ in (36+ cm)How far the roots reach, a guide to drought resilience and transplanting.

Flowers, foliage & fruit

Type: WildflowerWhat kind of plant it is.
Bloom: Jun–AugWhen it flowers.
Flower color: YellowThe bloom color, or colors.
Toxicity: None knownWhether any part is poisonous to people or pets.

Propagation & seed

Cold stratification: Required (cold, moist)Whether seed needs a cold, moist spell before it will germinate.
Propagation: Container, sprigsHow to start new plants.
Seed: ~2 million seeds per poundNotes on the seed and how to sow it.
Seed spread rate: SlowHow readily it self-sows. Slow or none means well-behaved, not a spreader.
Seedling vigor: MediumHow strongly young seedlings establish.
Vegetative spread: NoneWhether it creeps outward or stays put in a clump.