perennial

Caper Spurge

The Story

Plant Bio

Euphorbia lathyris is an erect, architectural biennial or short-lived perennial distinguished by its highly geometric growth form. In its first year, it produces a single, rigid stem clothed in glaucous, blue-green leaves arranged in precise, opposite pairs.

The second year brings terminal, branching clusters of chartreuse cyathia surrounded by triangular-ovate bracts. The entire plant is filled with a caustic, milky white latex that deters herbivores but poses a severe contact hazard to gardeners.

Uses & Benefits:

Provides a striking, geometric focal point with its blue-green, decussate foliage and architectural form.

Highly drought-tolerant once established, making it suitable for low-water gravel gardens and dry borders.

Flowers attract generalist insect pollinators, including flies and bees, while the toxic sap deters mammalian herbivores.

Essentials

At a Glance

Plant Type

Perennial

Height

79"

Width

35"

Light

Full Sun, Partial Sun

Zones

5, 6, 7, 8, 9, 10

Water

Low to moderate

Humidity

Low to moderate

Lifespan

Biennial or short-lived perennial

Native To

Europe, Asia, and Africa

Toxicity

Highly toxic if ingested; sap causes severe skin and eye irritation

Bloom period

Spring – Fall

In flower about 9 months of the year

Planting

How to Grow

Select a site in full sun to partial shade with well-drained soil, as the plant will rot in waterlogged conditions.
Sow seeds directly or plant containerized specimens in spring, ensuring the taproot is not severely disturbed.
Water moderately until established, after which the plant exhibits high drought tolerance.
Monitor the plant in its second year to deadhead spent flower heads before the seed capsules explosively dehisce.

Pro Tip

Wear heavy gloves and eye protection when handling this plant; the caustic milky sap causes severe skin blistering and temporary or permanent eye damage upon contact.

Keep It Thriving

Care Guide

Do

Wear protective gloves and safety glasses whenever pruning or handling the plant.
Plant in well-drained loam, sand, or clay soils.
Deadhead spent flowering stems to prevent aggressive self-seeding and garden escape.

Don't

Do not plant this species in wet, poorly drained soils where root rot is common.
Do not prune heavily into old, leafless wood.
Do not plant under the false assumption that it will actively repel moles or gophers.

Seasonal Care Calendar

Task	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Deadhead
Pest Check
Propagate
Spring Cleanup
Winter Prep

Watch Out For

Pests & Diseases

Common Pests

Common Diseases

In the Garden

Landscape Uses & Companions

Landscape Uses

Architectural AccentGravel GardenMediterranean GardenDrought-Tolerant Border

Companion Plants

Lavandula angustifolia Rosmarinus officinalis

Multiply

Propagation Methods

Good to Know

Common Questions

Caper Spurge questions

What zones can Caper Spurge grow in?

Caper Spurge is hardy in USDA Zones 5–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.

Is Caper Spurge deer resistant?

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

When does Caper Spurge bloom?

Caper Spurge typically blooms in spring through fall. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.

Does Caper Spurge need full sun?

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

Is Caper Spurge drought tolerant?

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