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Cleome hassleriana

spider flower

Cleomaceae

Southeastern Brazil, Paraguay, northern Argentina, Uruguay

Attracts Pollinators Attracts Butterflies Attracts Hummingbirds Deer Resistant Drought Tolerant

SunFull Sun – Part Shade

WaterLow · drought-tolerant

Overview

Cleome hassleriana is a fast-growing annual reaching 3-5 feet (90-150 cm) tall and 18-24 inches (45-60 cm) wide, with upright sticky stems and palmately compound leaves of 5-7 lance-shaped leaflets, each 2-4 inches (5-10 cm) long. The leaves and stems exude a pungent skunk-like odor when crushed, which deters deer and rabbits. Flowers form in dense terminal racemes that elongate progressively from June through frost, with individual flowers 1-1.5 inches (2.5-4 cm) across in shades of pink, white, lavender, or rose-purple. Each bloom has four petals and six long projecting stamens (4-5 cm), giving the flower a spider-like appearance. Bloom continues for 12-14 weeks. Long narrow seed pods 3-5 inches (7.5-12.5 cm) develop below the flowering raceme, splitting open to release reddish-brown seeds. Plants self-sow vigorously in zones 4-9, often appearing as volunteers the following season. The species can become invasive in some regions and is listed as a watch-list non-native in parts of the eastern United States. Hairs on stems and leaves can cause skin irritation in sensitive individuals.

Native Range

Cleome hassleriana is native to southeastern Brazil, eastern Paraguay, northern Argentina, and Uruguay, where it grows in disturbed grasslands and forest edges. The species was introduced to North American horticulture in the late 19th century and remains common in cottage gardens and Victorian-style plantings. It naturalizes in disturbed sites in the southern and central United States.

Suggested Uses

Cleome hassleriana is used as the back layer in mixed annual borders, cottage gardens, and pollinator plantings, spaced 18-24 inches (45-60 cm) apart for solid coverage. The vertical structure is used in mass plantings against fences and walls, where the 3-5 foot (90-150 cm) flower spikes give visual height through summer. Cut stems last 5-7 days in arrangements when harvested at the half-open raceme stage.

How to Identify

Cleome hassleriana is identified by tall upright stems with palmately compound leaves of 5-7 leaflets and dense terminal racemes of four-petaled flowers with prominently projecting stamens. The skunk-like odor when leaves are bruised is diagnostic. Seed pods are pencil-thin and arch downward below the open flower head as the raceme elongates.

Appearance

Size & Dimensions

Height3' - 5'

Width/Spread1'6" - 2'

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~14 weeks

Summer Fall

Bloom begins in late June or early July in USDA zones 5-7, continuing through first frost in October-November. The raceme elongates from below, opening 5-15 new flowers daily over a 12-14 week period. Individual flowers last 1-2 days but the continuous opening creates a steady display.

Detailed Descriptions

Flower Description

Pink, white, lavender, rose-purple

Foliage Description

Mid-green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 5-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam sand clay

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Cleome hassleriana grows in full sun (6+ hours daily); partial shade reduces stature by 30-40% and softens stem strength. Soil tolerance is broad: any well-drained loam, sand, or amended clay with pH 6.0-7.5 supports growth. Direct sowing 1-2 weeks after last frost when soil reaches 60°F (15°C) gives stronger plants than indoor-started seedlings, which often resent transplanting. Watering during the first 4 weeks supports establishment; mature plants tolerate drought of 2-3 weeks. Fertilization is generally unnecessary in average soils; rich soils produce floppy growth requiring staking. Plants tolerate heat to 95°F (35°C) without flagging.

Pruning

Pinching the central growing tip at 12 inches (30 cm) tall produces a branched habit and more flower racemes per plant. Spent flowers and developing seed pods can be removed at the base of the inflorescence to extend bloom by 2-3 weeks and limit self-sowing. Plants in exposed sites benefit from a single bamboo stake when stems exceed 4 feet (1.2 m).