An easily grown annual native to South America, cleome (Cleome hassleriana synonym C. pungens, C. spinosa) is a favorite in Southern gardens. The delicate pink, rose, purple, white, or bicolor spider-like flowers along with the spidery seedpods give it the common name, spider flower. It grows best in average, well-drained soils and in full sun to light shade. Somewhat drought tolerant, cleome will benefit from supplemental irrigation during dry periods. Many new dwarf hybrid cultivars (Cleome hybrida) have been bred for more compact growth habits and prolific blooms.
Depending on the cultivar or series, cleome will range in height 1½- to 5-feet tall with a 1- to 2-feet spread. The newer dwarf cultivars are 1½- to 4-feet tall by 1- to 2-feet wide, making them a good choice for smaller areas and containers.
Cleome bloom from June until frost. The 4- to 8-inch spider-like blooms start at the bottom of the stalk and move upwards. Deadheading, the removal the spent flowers, is not necessary. The flowers are followed by thin green seedpods that ripen to brown and split open to disperse the small seed. Older cultivars, such as the Queen series, produce viable seed and will potentially self-seed in nearby areas. Newer hybrids are sterile and do not produce viable seed.
The sticky, palmate green leaves have 5 to 7 leaflets that have a strong, sometimes unpleasant fragrance, and sharp spines at the base of each leaf. Most newer cultivars are odor and thorn free, making them a more desirable addition to the garden.
How to Grow
Seeds may be sown directly in the landscape after the fear of frost has passed. The soil temperatures should be 70 to 75° F. Thinly sow the seeds 4- to 6- inches apart and cover with ¼-inch of soil. Keep the bed moist, but not wet, until germination. Seedlings will appear in 7 to 14 days. Depending on the cultivar, thin the seedlings to a spacing of 10- to 15-inches apart. Seeds may also be started indoors 6 to 8 weeks before transplanting outside. Cleome will bloom 70 to 80 days after germination.
The Queen series seed have a better germination rate if they are chilled for 4 to 5 days prior to planting. To chill the seed, evenly spread them on a moist, not wet, paper towel, fold, place inside a zip-lock bag, and keep in the refrigerator. This series reseeds itself and should be considered for areas where the gardener wishes for it to return year after year. The hybrid Sparkler™ series seeds do not need to be chilled prior to germination. The Spirit™ series has the ability to self-sow, but may be established either by planting seed or by buying plants from a nursery. As the ‘Linde Armstrong’ and Señorita® series flowers are sterile and do not produce viable seeds, transplants must be purchased and planted into the garden.
After planting, add a thin layer of 1 to 2 inches of mulch to help retain moisture as well as discourage weed seeds from germinating. Due to the strong taproot, staking is usually not necessary.
Cleome works well in borders, background plantings, masses, cutting gardens, and containers. It contrasts well when combined with many other summer annuals, such as sunflowers, zinnias, cosmos, salvia, or celosia. Cleome makes a better impact in the landscape when planted in masses 2 to 3 feet wide. It is beneficial to plant other smaller annuals in front of the taller cleome cultivars as they tend to have bare lower stalks. Cleome is deer and rabbit resistant. The flower nectar attracts hummingbirds, butterflies, bees, and other pollinating insects. Another unusual visitor attracted to cleome is the hummingbird moth that visits the flowers at dusk.
Smaller cultivars, such as the Sparkler™ and Senorita® series along with the ‘Linde Armstrong’, have a more compact growth habit and are excellent additions to annual container combinations.
Overall, cleome is a tough annual. There are no serious insect or disease problems. Aphids, spider mites, and whiteflies can be a problem. It is susceptible to powdery mildew and rust in hot, humid climates; therefore, it is important to space the plants properly to allow better air circulation to help prevent infection.
In order to avoid disease issues the next year, remove dead plants after they are killed by frost.
- ´Helen Campbell´ has dramatic, pure white flowers and will reach a height of 4-feet and a width of 1- to 2-feet. The Royal Horticulture Society awarded this selection the prestigious Award of Garden Merit in 1993.
- ´Linde Armstrong´ is a dwarf, compact, odorless, and thornless grower with pink flowers that will reach 12- to 18-inches high and 12-inches wide. It is an Athens Select hybrid with sterile seed and is produced from cuttings. Transplants must be planted in the garden.
The Queen series is the oldest of the series bred cleome. The flowers are easily pollinated and produce viable seeds. The resulting seedlings will be similar to the parent plants, but not necessarily the same color. It is the tallest at 3- to 5-feet tall by 1- to 2-feet wide and will self-seed aggressively. The foliage has a strong odor along with sticky leaves with spines at the base. Mixed color seed blends are available along with individual color cultivars.
- ´Cherry Queen´-bright, cherry rose flowers
- ´Rose Queen´-pastel, rose-pink flowers
- ´Violet Queen´-purple flowers and the leaf edges are tinted purple
- ‘White Queen’-pure, white flowers
Señorita® series is a sterile, thornless hybrid that will not self-seed. The plants are 2- to 4-feet tall with an 18- to 24-inch spread, and have odorless leaves that are not sticky. The darker green foliage is smaller, and the plants do not become leggy. These hybrids do not produce seed and can only be started from transplants.
- ´Señorita® Rosalita´-rose pink flowers
- ´Señorita® Blanca´-pure white flowers
- ´Señorita® Mi Amor´- pink flowers
The Sparkler™ series was the first hybrid cleome developed. It is more vigorous and heavier blooming than the Queen series. The seed germinate easily, so no pre-chilling is necessary. This selection is an upright grower that reaches a height of 2- to 3-feet tall and 1½- to 2-feet wide. As they are shorter and bushier, the Sparkler™ series is an excellent choice for containers.
- ´Sparkler™ Blush´-blush pink and white flowers
- ´Sparkler™ Lavender´-pastel lavender flowers
Spirit™ series is more compact with a height of 2- to 4-feet tall by 15- to 18-inches wide. It has a better branching growth habit, but does have thorns and sticky foliage. It also has the ability to self-seed.
- ´Spirit™ Appleblossom´-pale pink fading to white flowers
- ´Spirit™ Frost´- white flowers
- ´Spirit™ Violeta’ -pink-purple flowers