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Growing Cleome from seed

Growing Cleomes from Seed

Spider! Flower! Spider! Flower! If you're alternating between screaming and swooning right now, and you love high drama, then you might want to think about planting Cleome hassleriana in your ornamental garden.

The spider flower plant, also simply called by its genus name "cleome," ranks among the easiest plants to grow. It begins blooming when others start to fade and keep kicking until the first fall frost.

Cleomes reseed easily, dress up xeriscapes, and make great cut flowers. They're also a valuable forage plant—thanks to their seeds and nectar—for a variety of avian and insect garden visitors.

A Quick History of Cleomes

Cleome hassleriana is native to South America below the equator, from Brazil to Argentina. Other nearly-identical types of the Cleome genus are indigenous to North America, with cultural relevance to native Americans. Cleome serrulata, for example, was harvested for its seeds and used to make tortillas and add bulk to porridges. C. serrulata is also known as Rocky Mountain Beeplant, Waa (Navajo), and Skunkweed, and aside from culinary uses, products derived from the seed pods were used to create paint and pigment bases, and the leaves were used as deodorizers.

Native Americans used to boil the leaves to relieve stomach aches, and many generations of youngsters have tried to smoke cleome leaves in an attempt to get high...but were sorely disappointed by the results.

There's no recorded history of how C. hassleriana made it north, though it's very likely the seeds were carried by migrating birds, or through ancient trading routes. Different wild varieties are known to thrive in the North American western regions, from dry washes to vacant lots.

Cleomes are in the caper family, and flowers on the caper bush share the same protruding stamens as cleomes. The seed-pods produced by cleomes at the end of their life cycle are its counterpart to the popular pickling fruit.

Cleome in the Garden

Cleome hassleriana earned the common name "spider flower" due to its long, hairlike stamens, which "spike" out from the dense clusters of flowers that explode from terminal stalks. It's difficult to get a sense of scale when checking out photos of cleome; you might assume they're similar to clovers or bee balm.

Yeah, sure. If those plants were exposed to radiation and grew into the botanical equivalent of a Mike Mendez horror flick. Cleomes, by comparison, are ginormous.

B movies are pretty thrilling, especially when they have bad words in their titles, but there's nothing terrifying about spider flowers unless you're allergic to bees. These suckers attract beneficial pollinators like nobody's business. Their large flowers provide nectar to hummingbirds, and when they go to seed (which they do, easily) they draw in all sorts of birds.

Like a radioactive botanical experiment, cleomes are extremely fast growers with a very long blooming period. In fact, the blooms begin even as the stalks continue to grow as if they just can't wait to begin their colorful displays.

Your garden will continue to explode well into fall if you plant these beauties en masse near other varieties that tend to "peter out" in the late summer heat.

Choosing a Spot for Cleome

Spider flowers are quite tall, making them excellent background plants. Their drought-tolerance allows them to hang out in neglected areas of your yard or garden, or on the margins of your irrigation zones. Their appearance and exaggerated size "tie together" gardens that use visually similar-in-appearance but scaled-down plants, such as mints and alyssums, in the foreground.

Cleome can get a little "leggy" in the richest soil, and the tallest plants might need staking in windy areas. Some gardeners prefer to plant complementary flower varieties in front of their cleome plants to hide their bases, but most of the time, cleomes look stunning on their own, from root to bloom. They should be planted in clusters for the best effect.

Cleomes look wonderful when planted near feathery, tall ornamental grasses, or among echinacea, cosmos, zinnias, and asters. When Columbine blooms taper off, their foliage makes a great footnote to cleome's towering stalks. Cleomes pick up the slack when delphiniums and other tall, columnar, early-blooming plants pack it in.

Enough of being coy about spider plants' beauty in the garden. Here are the specifics!

USDA Hardiness Zones: Spider flowers are annual, and thrive in zones 2-11.

Sunlight Preferences: Full sun to afternoon shade.

Moisture Preferences: For best growth and flowering, keep your plants evenly moist, but they do tolerate drier soils once they mature.

Soil Quality: Cleome will settle for any type of soil, as long as it drains easily. We recommend adding compost to your cleome beds to improve drainage and to give your plants the best start.

Soil pH: 6.0 to 7.0.

Plant Height: A whopping 2 to 6 feet! That's without the help of shadow governments or mad scientists.

Plant Spread: 1 to 2 feet.

Growth Habit: Cleome are upright-growers; plants are clustered at the tops of tall, leafy stalks.

Flowers: Delicate flowers emerge in loose 6" clusters from the tops of terminal spikes.

Paddle-shaped petals bloom in shades of pink, lavender, purple, and white.  

Foliage: Dark green, sticky seven-lobed palmate leaves grow from a central stalk. As the plants grow, your neighbors might accuse you of growing weed. (You can differentiate between your grow patch and your cleomes by noting that the leaves of the latter lack the serrations of the former).

At the base of each leaf, a tiny thorn reminds us that spiders do bite; we recommend wearing gloves when handling your cleome plants.

Fragrance: Both the leaves and flowers are fragrant, though the aroma varies from pleasant to...well, overwhelming. Some say the leaves don't just look like cannabis; they smell like it, too. Some describe the odor as "skunky" and off-putting; others dismiss it as simply "earthy" or "vegetative."

Maintenance: Deadheading recently-wilted flowers will curtail self-seeding unless you want them to multiply and emerge en mass the following spring. Pinching the tops of your cleome plants in early spring will help them retain a more compact, bushy shape. Keep an eye out for volunteer seedlings the next spring; even if you want your cleomes to naturalize, you don't want them to crowd one another or neighboring plants. Thin them out as necessary.

Cut Flowers: Cleomes make good cut flowers, though they don't last long; some gardeners report success in displaying them when dried. Once again, be mindful of the plant's thorns. Because of these, cleomes probably aren't the best choice for bouquets. Eric Larson of Leslie Land: In Kitchen and Garden recommends the following steps for getting the most out of your cut cleomes:

  • Cut the flowers in the early morning when the dew is still on the plant.
  • Remove the lower leaves.
  • Immediately immerse the stems—up to the base of the flower heads—in lukewarm water for 1 to 2 hours prior to adding them to your arrangements.

Pests and Diseases: Cleome is deer and rabbit resistant, and while aphids are attracted to its sticky leaves, it's not particularly prone to damage by invertebrates, mold, or viruses.

Growing Cleome From Seed

Cleome doesn't transplant well and does best when it's direct-sown immediately after your last frost. Plan to keep your planting area moist with the mist setting on your garden hose. Get ready; once your cleome plants emerge, they really take off!

Seed Preparation: A week or two of cold stratification might boost your germination speed, but it's not necessary.

Sowing Depth: Press the seeds onto the damp surface of smooth, prepared soil. Cleome seeds require sunlight to germinate.

Plant Spacing: Plant cleome seeds or thin seedlings 12" to 24" apart.

Germination Period: Cleome germinates in 7 to 21 days, most often at the 14-day (ish) mark under optimal conditions.

Indoor Seed Starting: You can start your seeds indoors, under lights, 4 to 6 weeks prior to the last spring frost, on a heat mat set to 70-75°F. Once your plants have emerged and reached a height of 6" (be sure to keep the lights just above the seedling, raising it as necessary, to prevent legginess) transplant them outdoors or into large containers. Transplanted cleomes typically don't thrive as well as direct-sown plants.

About Seed Needs

We're a family-operated small business based up here in Michigan, and we know firsthand the importance of fresh, high-quality seeds for successful gardening. That's why we started selling seeds back in 2006, and thanks to a great crowd of loyal, satisfied customers, we've been able to grow our little company and continue to do what we love.

We thrive on feedback to improve our business and learn what varieties you want us to carry. Contact us with your questions, or simply to share your gardening success stories! Heck, even the occasional disaster can be a learning experience for everyone, and we've always got a few pointers to help you improve your gardening skills, which we include in our gardening blog.

Whether your goal is to add healthy, homegrown fruits and veggies to your family's menu, experiment with herbal remedies, support local wildlife and pollinators, or create a stunning landscape that will put your neighbors to shame, we've got you covered... and we're grateful for all our customers who've had us covered all these years!

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