I grew cleome from seed in my cutting garden last year for the first time and was delighted with, well, so many parts of this plant! First, it’s height: it grew at warp speed and was easily 5 feet tall by the latter half of the summer. Farmer florists and cut flower growers can rejoice at this plant’s long, strong, straight stems.
Secondly, those flowers. Covered in whiskery white, pink, magenta, and purple flowers, it’s no wonder that cleome is also commonly called “spider flower”. The flowers were like little jewels on the end of a magic wand, and they looked airy and delicate next to my chunky (yet very beloved) sunflowers and marigolds.
Lastly, its hardiness. My gardens experienced both flooding, as well as periods of drought last year which definitely wreaked havoc on some members of my garden. Not cleome! It flowered steadily from summer through fall’s first hard frost with little assistance from me.
I can’t tell if its look is elegant, or more otherworldly and weird – either way, this low-maintenance plant is worth trying. Read on and learn more about growing cleome in the garden.
Cleome Overview
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What Is It?
Cleome is an herbaceous flowering plant that is most commonly grown as an annual, although it may be hardy year-round in our absolute warmest growing zones. It is known for its one-of-a-kind, spider-like flowers, which attract hummingbirds, butterflies, bees, and moths. This species is thought to be mostly pollinated by bats in its native tropical habitat.
Characteristics
This plant features tall, stalk-like stems that are slightly hairy in texture. These glandular hairs can be sticky and may give off a musky, not totally unpleasant scent. Stems branch out to palmate leaves composed of 5-7 leaflets that are slightly fuzzy in texture. Small spines protrude from the base of each leaf petiole. Although the fragrance and leaf shape of this plant strongly resembles that of Cannabis sativa, cleome is not at all related.
Cleome is a long-flowering annual, and the blooms persist from early summer to the first hard frost. The flowers are really the stars of this plant! An unbranched 6-8 inch wide cluster of flowers (called a raceme) forms at the very top of the stem. Each individual flower features white, pink, or rosy purple petals that eventually open to show 3-inch long, thread-like stamen.
Elongated seed pods that resemble miniature green beans emerge from each individual flower. Gardeners interested in seed saving can collect and dry the pods, which open quite easily. Or, seed pods can be left on the plant, adding to its otherworldly vibe. Cleome self-seeds readily, although the plants aren’t overly aggressive or considered invasive. Some sterile hybrid cultivars may not produce seeds at all.
This genus grows rapidly and some varieties can easily reach 6 feet tall. Several newer cultivars have been bred to be more manageable for the home gardener and stand a compact 2-3 feet tall, with spineless, easy to handle stems and minimal fragrance.
Native Area
There are over 100 species of the genus Cleome spread throughout South America, Africa, and areas of Asia. There is even one native to North America: C. serrulata, also called the Rocky Mountain bee plant.
Cleome houtteana, which is the spider flower most widely grown by gardeners as an ornamental plant, is native to Paraguay, Uruguay, Argentina, and parts of Brazil. Most types of cleome are found in disturbed areas including roadsides, gravelly ditches, thickets, and meadow edges.
Planting
This is a versatile flower that works beautifully in beds, borders, mass meadowscapes, and containers. The lower stems of some cleome cultivars tend to be bare of leaves, so consider positioning them behind a mounded and floriferous perennial, such as coreopsis or hardy geranium.
Pair them with other sun-loving, fuss-free annuals like zinnias, cosmos, and sunflowers for a colorful cutting garden. Create a charming purple and pink cottage border by interplanting cleome among lavender and roses.
In containers, this plant shines as a “thriller plant” with its tall, upright stems that rarely need staking. Try them in the back of a pot filled with yellow gem marigolds and creeping jenny for heat-tolerant, pink and gold patio display. Shorter cultivars like ‘Linde Armstrong’ stand just 12-18 inches tall, perfect for containers.
Growing from Seed
These flowers are easy to from seed! Direct sow seeds in the garden after all threats of frost have passed and the soil temperature is close to 70°F (21°C). Sow 2-3 seeds every 12 inches. Lightly press seeds down and cover with just ¼ inch of soil.
Keep the soil moist but not waterlogged until seeds have germinated, usually 10-28 days after planting. Thin seedlings to one every 12-18 inches to encourage healthy, bushy plants and prevent disease.
Gardeners in colder climates may want to get a jumpstart on the season and start cleome seeds indoors. Sow seeds 6-8 weeks before the average date of last frost. Plants started indoors should be acclimated gradually to the outdoors (“hardened off”) for 7-10 days prior to planting out.
How to Grow
This is an easy plant to grow and its festive, fun flowers make it an especially appealing plant for new gardeners and kids.
Light
Cleome really grows and flowers best in full sun, although they will tolerate partial shade. Too much shade can lead to leggy, floppy plants with fewer flowers. Six to eight hours of daily sun will ensure these plants flower at their very fullest.
Water
This plant has low to moderate water requirements. It looks its best when regularly watered, however it can easily handle short periods of drought. A layer of organic mulch around the plant will help the soil retain moisture for longer periods.
Soil
Decidedly unfussy, cleome has no particular soil requirements. In its native range, cleome has a tendency to grow in gravelly, disturbed soils; it’s rarely found in wet or heavy clay. In the garden, cleome grows well in average, well-drained soil.
Temperature and Humidity
Cleome loves warm, sunny weather and really thrives when temperatures are between 70 and 90°F (21-32°C). It is not frost tolerant and will die once temperatures dip below 32°F (0°C). It is relatively tolerant of humidity, however prolonged periods of extra high humidity and rainfall make cleome more susceptible to fungal diseases.
Fertilizing
Fertilizer is rarely needed with this plant and overfertilizing can actually lead to leggy growth. Amend particularly poor soil with a healthy dose of compost prior to planting. Container-grown cleome plants may benefit from a slow-release fertilizer applied halfway through the growing season.
Maintenance
Little to no maintenance is needed for healthy attractive flowers. Pinch or prune the tops of stems to encourage a bushier growth habit, if so desired. Deadheading is not required for this plant, however gardeners can snip off flowers as they fade to prevent seedpods from forming.
These plants have sturdy taproots that keep them upright for the most part, however you may want to stake individuals if you garden in an especially windy region.
Popular Varieties
Here are the most popular varieties and species for home gardeners.
‘Helen Campbell’
This 4-foot tall cultivar produces large, pure white flowers. Plants can grow to be 1-2 feet wide and require little to no maintenance. Pair with other white flowers such as Flowering Tobacco, phlox, and tuberose, for a glowing moon garden.
‘Linde Armstrong’
This cultivar is very compact, standing just 12-18 inches tall. Its short height and lovely rosy-pink flowers makes ‘Linde Armstrong’ ideal for containers. This plant is particularly heat-tolerant and is a great choice for southern gardeners.
‘Senorita Rosalita’
‘Senorita Rosalita’ is the perfect choice for the gardener who doesn’t want to wrestle with spines or surprise seedlings. This cultivar is spineless, odorless, and sterile, meaning it does not produce seedpods.
Because they don’t produce seed, this cultivar needs to be started from transplants. ‘Senorita Rosalita’ sprouts beautiful lavender-pink flowers up and down its stem as opposed to just at the very top. It typically stands 2-4 feet tall.
‘Queen’ Series
This is the oldest and tallest collection of the cultivars. Plants stand 3-5 feet tall and will self-seed very readily, making them excellent plants for a meadow or mass planing.
‘Cherry Queen’ features bold, bright pink flowers, ‘Violet Queen’ produces purple flowers as well as purple-edged leaves, and ‘Rose Queen’ bears soft pink blooms. These cultivars have the traditional scent, sticky leaves, and spiny stems of the well-known species.
‘Sparkler Blush’
A 2002 All-American Selections winner, this cultivar produces eye-catching pink and white bicolor blooms. ‘Sparkler Blush’ stands 3-4 feet tall with plenty of full, bushy foliage. It flowers freely in full sun and even tolerates occasional drought.
‘Spirit’ Series
Commercially available in ‘Spirit Appleblossom’ (a lovely pale pink and white), ‘Spirit Violeta’ (a light purple), and ‘Spirit Frost’ (clear white), this series stands 2-4 feet tall. Like the ‘Queen’ series, these plants have the sticky leaves and spines of traditional varieties.
Common Problems
This is a hardy flower with few problems. Older varieties bear unpleasant spines and sticky stems that most deer, rabbits, and woodchucks find unpleasant.
Pests
Few pests are found on these annuals. Occasionally, aphids, harlequin beetles, and various cabbageworms will feed on cleome foliage. Recent DNA studies found that the Cleomaceae family is closely related to Brassicaceae, which is why many of the pests that plague our brassicas (cabbage, broccoli, and kale) can occasionally be seen on cleome. Interestingly enough, it has been used by some growers as a trap crop to protect their vegetable crops.
Individual insects can be removed by hand, however large-scale infestations will require insecticidal soap or complete removal of plants to avoid pests from overwintering.
Diseases
Cleome is susceptible to rust and powdery mildew in particularly hot and humid climates. Providing adequate air circulation between individual plants is key to preventing these two diseases. Space seedlings 12-18 inches apart, depending on the variety.
Keep leaves and stems dry by watering at the soil level with a watering can or drip irrigation, instead of overhead watering with a sprinkler.
