If cleome flowers aren’t among some of the most popular annuals sold at home improvement stores and nurseries, it may be due in part to their homely appearance as young seedlings. Unlike pert marigolds or dazzling New Guinea impatiens, cleomes usually don’t start blooming until they’re well established in the garden, so they can look rather weedy in their 6-packs. However, once the flower clusters emerge, you’ll want to add this plant to your list of easy-care favorites.
Spider flowers don’t emit a noticeable fragrance, but hummingbirds and butterflies didn’t get the memo, because they are drawn to these flowers all summer long. An additional unusual but welcome visitor to these flower clusters is the hummingbird moth, which looks so much like a hummingbird as it darts about at twilight you’ll do a double-take.
A member of the Capparaceae family, the genus Cleome is often referred to by the common names of spider flower, rocky mountain bee plant, and stinking clover. As an annual you can grow this in all climates; the tropical plant is perennial only in zones 10 and 11.
Averaging three to four feet in height, cleomes provide a welcome tall focal point in the annual garden where compact bedding plants tend to rule. What's more, the upright plants need no staking. The pink, purple, white, and lavender flowers complement many garden designs while pleasing visiting pollinators as well.
Cleome flowers look like few others. Many petals radiate from a central point, forming an umbel, or cluster, which tends to be softball-sized. Long stamens give flowers a spiky look. Even the foliage is attractive, being fern-like and delicate.
How to Plant Cleomes
Cleome flowers are easy to start in the garden from seed. Perhaps too easy, as the plants can self-seed to the point of being a nuisance. The seeds need light to germinate, so you can just sprinkle them in the garden after the danger of frost is past, and look for seedlings after 10 days. Alternatively, sow them in the autumn, and they’ll germinate when conditions are just right in your area.
If you do allow the plants to self-seed, thin the newly emerging seedlings to allow at least 18 inches between plants. This improves the vigor of individual plants, encouraging the most blossoms from each plant.
Cleome flowers grow best in full sun, as shady conditions can make them grow so tall as to topple over. If you start with transplants, you’ll see blossoms from early summer until the first frost. Gardeners growing cleome flowers from seed usually see their first flowers in mid to late June, depending on the climate.
Caring for Cleome
Cleome plants are drought tolerant, making them a welcome addition to the xeriscape garden. Add a 3-inch layer of organic mulch to their planting bed, and you’ll decrease your watering chores even further. Unlike some annuals, spider flowers are light feeders and giving them too much nitrogen results in leggy plants.
Cleome flowers thrive in average garden soil and shrug off flower insect pests and diseases. If you want to limit cleome’s self-seeding habit, spend time each week plucking the long seed pods that form under the flowers throughout the season.
Cleomes in the Garden
Cleome flowers are excellent candidates for the back of the flower border, where their lanky stems can hide behind other plants, but their festive flower clusters can sway in the breeze above other flowering annuals. Plant cleomes in clusters of five plants or more, as to avoid the "soldiers-in-a-row" visual that single plants suggest.
The casual form of cleomes suits the cottage garden or naturalized meadow well. Mix cleomes with zinnias, cosmos flowers, black-eyed Susans, salvia, or celosia. These plants all thrive in the same sunny conditions and moderate irrigation that cleomes love.
You can grow cleome in large containers, but choose a compact variety like the Sparkler series for best results. Combine your potted cleomes with a mounding flower like vincas and a trailing flower like petunias for the most full and lush look.