Cleome gynandra: complete guide

Overview

Cleome gynandra, popularly known as Spiderwisp or Cat's Whiskers, is an annual herbaceous plant originating from tropical and subtropical regions of the Old World. This plant is renowned for its striking, hairy flowers arranged in loose, elongated racemes along the stems. The plant typically reaches a height of 60 to 90 centimeters and offers a unique visual structure in the garden thanks to its thin, protruding stamens that resemble spider legs - hence the name Spiderwisp.

Cleome gynandra is relatively easy to grow and highly suitable for summer flower gardens in temperate climates. The plant grows rapidly and produces nearly continuous flowers from June through October. This is an ideal choice for cottage gardens, cut and dried flower arrangements, and mixed borders for maximum visual impact.

Appearance and Bloom

The plant develops upright, slender stems that are often slightly hairy with a deep green color. The leaves are hand-shaped and compound, typically featuring five to seven narrow, lance-shaped leaflets with serrated edges. The foliage is bright and vital, providing good contrast with the dramatic flowers.

The flowers are the highlight of this plant. They appear in long, loose inflorescences at the tops of the stems and have four delicate pink, purple, white, or red petals. The very long stamens and pistil give the flower its characteristic spider-leg appearance. Each flower opens for only one day, but the plant produces so many blooms that there is always something flowering. The flower has a subtle, pleasant fragrance, especially in the morning.

After flowering, the plant forms long, thin pods containing dozens of tiny seeds. These seeds can be saved for sowing in the next season, allowing this plant to self-propagate if allowed to set seed.

Ideal Location

Cleome gynandra thrives best in a warm, sunny location with at least six hours of direct sunlight daily. A south- or west-facing position is ideal. The plant tolerates shade but produces fewer flowers in partial shade. In very warm climates, light afternoon shade may be beneficial to prevent desiccation.

The plant is not very particular about wind, but very strong winds can cause breakage of the thin stems. Choose a somewhat sheltered location where air circulation is possible without extreme exposure to storms.

Soil

Cleome gynandra grows in virtually any reasonably fertile soil as long as it is well-draining. The plant tolerates poor soils but will grow better with the addition of compost or peat. pH can be neutral to slightly acidic (pH 6.0 to 7.5). Avoid heavy clay soils without amendments, as water stagnation can cause root rot.

Add sufficient organic material before planting, approximately 5 to 8 centimeters of well-processed compost worked into the top 15 centimeters of soil. This increases water-holding capacity and nutrient availability. For container culture, use well-draining potting mix with the addition of perlite or sand.

Watering

Watering is critical during the growth and flowering period. Water as soon as the top 2 centimeters of soil feels dry, but ensure the soil never remains continuously waterlogged. Young plants require more water than mature specimens. In hot summers, daily watering may be necessary.

Water at the base of the plant rather than from above, as wet foliage is susceptible to fungal diseases. Early morning watering is ideal. Ensure potted plants can drain well through holes in the bottom.

During dry periods, mulching with organic material can improve moisture retention. Approximately 5 centimeters of organic mulch around the plant (not against the stem) helps keep soil moisture consistent.

Pruning

Cleome gynandra grows rapidly and can become quite tall. Pinching the tops when the plant is 15 centimeters high promotes branching and a more compact form. Later in the growing season, spent flowers can be removed (deadheading) to encourage more blooms.

To keep the plant neat and promote branching, remove any damaged or dead branches as needed. At the end of the season, the plant can be cut back significantly, although it is usually treated as an annual plant and removed after the first frost.

Maintenance Calendar

May-June: Sow seeds after last frost, or plant young seedlings. Place in full sun. Begin regular watering.

July-August: Plant grows rapidly and produces flowers. Remove spent flowers to promote more blooming. Check for insects. Ensure soil remains moist.

September-October: Flowering continues. Seed pods can ripen; collect them for next year if desired. Begin preparing for autumn. Reduce watering slightly.

October-November: Plant care ends as temperatures drop. After the first frost, the plant dies off. Remove dead plant material from the garden.

Winter Hardiness

Cleome gynandra is not winter hardy in temperate climates and is usually grown as an annual. The plant cannot tolerate hard frost. In areas with winters where temperatures drop below 5 degrees Celsius, the plant must be resown each year, or young plants must be purchased.

In very warm regions, the plant can grow as a short-lived perennial, although it typically still performs poorly if hard frost occurs. In frost-free areas, mature plants can overwinter in a warm, sheltered location.

Companion Plants

Cleome gynandra combines well with other tall, slender plants such as cosmos, Salvia species, and amaranths. Low-growing flowers like marigolds, zinnias, and portulaca form a nice base layer beneath this tall plant. Silver-foliaged plants like artemisia provide nice contrast with cleome's fine texture.

In borders, cleomes work well as a background for lower-growing flowers. For a tropical garden combination, add other exotic annuals like tithonia and cosmos. Cleome also works well in large containers, especially in groupings of three or five.

Conclusion

Cleome gynandra offers an easy-to-grow, dramatic addition to summer gardens. With its unusual flower form, long flowering period, and slender silhouette, this plant provides exotic allure without requiring much maintenance. Whether you garden in the Netherlands, Belgium, or Germany, this annual flowering plant will certainly draw the attention of passersby and add special structure to your garden.

Available at specialized garden centers and seed suppliers such as Gamma and Intratuin. GardenWorld.app also offers advice on integrating this plant into your garden design.