shrubN. America Native

Einstein Summersweet

Clethra alnifolia 'Einstein'

Not currently listed at our partner nurseries.

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Essentials

At a Glance

Plant Type

Shrub

Height

48 inches

Width

48 inches

Light

Full Sun, Partial Sun, Shade

Zones

4, 5, 6, 7, 8, 9

Water

Medium to Wet

Humidity

Tolerates high humidity

Lifespan

Long-lived shrub

Native To

Eastern North America

Toxicity

Non-toxic to humans and pets

The Story

Plant Bio

Clethra alnifolia is a deciduous shrub native to eastern North America, prized for its fragrant summer flowers that bloom when few other shrubs do. It's known for its adaptability to moist, shady sites and its attractive yellow fall color. Einstein ('Novacleein') is a selection noted for its exceptionally long, elegant flower racemes, which can reach up to 12 inches. It maintains a compact, rounded habit perfect for smaller gardens.

Bloom Period:

EarlyLate

Uses & Benefits:

Valued for its wonderfully fragrant, bottlebrush-like white flowers that bloom in mid to late summer when few other shrubs are in flower. It also provides excellent, clear yellow fall color.

Its tolerance for wet soils makes it a superb choice for rain gardens, boggy areas, or low spots in the landscape. It is also highly salt tolerant, making it suitable for coastal gardens.

A magnet for a wide range of pollinators, including native bees, honeybees, and butterflies. It is a larval host for the Sweetfern Underwing moth (Catocala antinympha).

Marketplace

Where to Buy

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Planting

How to Grow

Select a spot with moist, acidic soil and partial shade.
Dig a hole twice the width of the root ball.
Amend heavy clay soil with compost to improve drainage.
Set the plant at the same depth it was in the pot.
Backfill the hole and water thoroughly to settle soil.
Apply a 2-3 inch layer of mulch around the base.

Pro Tip

Plant in a location with morning sun and afternoon shade to maximize flowering without stressing the plant in hot climates.

Keep It Thriving

Care Guide

Do

Provide consistent moisture, especially during dry spells.
Use an acidifying fertilizer if leaves show chlorosis.
Allow it to sucker to form a natural colony if desired.
Plant in a spot with good air circulation.

Don't

Don't plant in dry, alkaline soils.
Avoid letting the soil completely dry out.
Don't prune after new growth begins in spring, or you'll remove flower buds.

Seasonal Care Calendar

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

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Fragrant border accentMoisture-loving foundation plantPollinator garden standout

Companion Plants

Itea virginica Lobelia cardinalis Osmunda cinnamomea Rhododendron viscosum Vaccinium corymbosum

Multiply

Propagation Methods

Good to Know

Common Questions

Einstein Summersweet questions

What zones can Einstein Summersweet grow in?

Einstein Summersweet is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Einstein Summersweet deer resistant?

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

When does Einstein Summersweet bloom?

Einstein Summersweet 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 Einstein Summersweet need full sun?

Einstein Summersweet does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.