shrubN. America Native

Ames St. Johnswort

Hypericum kalmianum 'Ames'

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Essentials

At a Glance

Plant Type

Shrub

Height

30 inches

Width

30 inches

Light

Full Sun, Partial Sun

Zones

4, 5, 6, 7

Water

Low to moderate

Humidity

Adaptable

Lifespan

Deciduous shrub

Native To

Great Lakes region, North America

Toxicity

Toxic if ingested

The Story

Plant Bio

Hypericum kalmianum is a small, dense, rounded deciduous shrub native to the Great Lakes region, valued for its adaptability and long bloom time. 'Ames' is a cultivar selected for its compact, uniform habit and profuse, bright yellow, five-petaled flowers with a prominent puff of stamens. It also features attractive blue-green foliage.

Bloom Period:

EarlyLate

Uses & Benefits:

The combination of cool, blue-green foliage and cheerful, sunny yellow flowers provides a long season of interest. Its neat, rounded habit requires little pruning to look good, and the persistent seed capsules add winter texture.

This is an extremely tough and adaptable shrub, perfect for low-maintenance landscapes, parking lot islands, and roadside plantings. Its dense root system can help with erosion control on slopes.

The pollen-rich flowers are a magnet for bumblebees, native bees, and other pollinators. It is a host plant for the Gray Hairstreak butterfly. Its dense branching provides cover for small birds.

Marketplace

Where to Buy

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Planting

How to Grow

Select a location in full sun with well-drained soil
This plant is not fussy about soil type or pH
Dig a hole as deep and twice as wide as the pot
Set the plant in the hole, ensuring the crown is at soil level
Backfill with native soil and water thoroughly
Water regularly during the first season to establish

Pro Tip

For the densest form, prune the entire shrub back by about one-third in early spring before new growth begins.

Keep It Thriving

Care Guide

Do

Plant in full sun for best flowering and form.
Provide good drainage; it dislikes wet feet.
Prune in early spring to encourage bushy growth.
Water during extended droughts, though it is drought tolerant once established.

Don't

Don't plant in heavy, waterlogged soil.
Avoid planting in deep shade, which leads to poor flowering and leggy growth.
Don't over-fertilize; it thrives in average to lean soils.
Avoid shearing into a formal shape; its natural form is best.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Mulch
Plant
Prune

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Tough, low hedge or border plantingBright accent in a rock garden or dry slopeMass planting for sunny, difficult sites

Companion Plants

Echinacea purpurea Rudbeckia fulgida 'Goldsturm' Schizachyrium scoparium Salvia 'May Night' Penstemon digitalis

Multiply

Propagation Methods

Good to Know

Common Questions

Ames St. Johnswort questions

What zones can Ames St. Johnswort grow in?

Ames St. Johnswort is hardy in USDA Zones 4–7. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Ames St. Johnswort deer resistant?

Yes — Ames St. Johnswort is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.

When does Ames St. Johnswort bloom?

Ames St. Johnswort typically blooms in mid-summer through late summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Ames St. Johnswort need full sun?

Ames St. Johnswort does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.

Is Ames St. Johnswort drought tolerant?

Yes — once established (usually after the first full season), Ames St. Johnswort handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.