How to Plant and Grow Spider Flower

Growing up to 5 feet tall, cleomes (a.k.a. spider flowers) are striking annual plants that provide an eye-catching focal point at the back of a garden—and they don't even need to be staked to stay upright. Most commonly available in shades of white, pink, and purple, the spider flower’s airy blooms add a tropical flair to mixed borders. What’s more, hummingbirds and other pollinators (such as butterflies and hummingbird moths) love spider flowers for their generous nectar supply.

Spider flowers begin blooming as soon as they are established (about 10 weeks after seed germination) and won't stop until they are knocked out by the first frost. Even after the blooms fade, the long, narrow seed pods add interest to the display. In late summer and early fall, the spindly seed pods project outward from the main flowering stem, adding to the spiderlike quality of the flower stalks.

There are some caveats to the easy-growing spider flower, however. Most notably, its ability to self-seed prolifically in the right conditions. The foliage of spider flowers, which closely resembles the look of a marijuana plant, also produces a musky, skunk-like odor which some find offensive. Lastly, some cultivars will have sharp thorns and a sticky ooze on the stems after the flowers have bloomed, so it’s best to wear gloves when handling the plant.  

Where to Plant Spider Flower

As long as your spider flowers are planted in full sun and well-drained soil with a decent amount of organic matter, they will bloom all season long. Given their sturdy height, spider flowers make great backdrops or centerpieces for flowerbeds—particularly in lush, colorful gardens designed to attract pollinators. 

Unless you plan to manage the spider flower's self-seeding habit, it's best to plant it in a place where you will enjoy having it return—possibly for several years.

Tall cultivars of spider flowers may not be suitable for containers, but many new dwarf varieties, like the C. hassleriana ‘Sparkler’, would work as well in containers as they do in the ground. Just be sure to place them in an area that receives full sunlight for large portions of the day.

How and When to Plant Spider Flower

You can sow spider flower seeds directly in the ground in late spring when the danger of the last frost has passed. Loosen the soil and sprinkle the seeds on the surface, covering them with only a light layer of soil. Keep the soil consistently moist as the seeds germinate. They should begin to sprout within a week or two. Once seedlings emerge, thin them out until they are about 8 inches apart. If need be, you can thin them again to approximately 18 to 24 inches apart once the plants are established. Just make sure the plants have plenty of air circulation to avoid issues with pests and
diseases.  

If you are planting nursery-grown plants or transplants, you may want to harden them off for a few days by placing them outside for a few hours each day and gradually increasing the amount of outside time.

When you are ready, dig a hole as wide and deep as the root ball and space the plants at least 8 inches apart. Tamp down the soil gently and then water the plants thoroughly.

Spider Flower Care Tips

Spider flower plants are prolific bloomers, and thus, produce lots of seeds. As their thin seedpods ripen and burst open, their tiny seeds scatter about the garden. This means that if you plant spider flowers once, you may be blessed with new plants for years to come—without any extra effort on your part. They are not considered invasive but if left unchecked, spider flower plants can grow profusely. The best way to control seed spread is to remove seedpods before they open and add a layer of mulch around the plants to prevent any missed seeds from taking root.

Light

Plant spider flowers in full sun for a dense habit and the best floral display. While the plants can handle partial sun situations, they are unlikely to bloom as profusely without access to ample direct sunlight.

If you must plant your spider flowers in a shaded area, make sure they get as much of the full morning and early afternoon sunlight as possible and let them take shelter from the harsh late-day sun.

Soil and Water

Spider flowers thrive in average to rich well-draining soil, ideally with a pH of 6 to 7.

While your spider flowers are getting established, keep the soil evenly moist, but not soggy. If you like, you can add a 2 to 3-inch layer of mulch to help retain the soil moisture and block volunteer plants from emerging.

Once established, spider flowers are fairly drought-tolerant (and could be a good addition to xeriscape gardens), but you may want to give them supplemental water if conditions get very dry.

Temperature and Humidity

Spider flowers love summery weather when daytime temperatures are between 70 and 85 degrees and no lower than 60 degrees at night. They are not frost-tolerant and will likely die when temperatures drop below 30 degrees Fahrenheit.

Spider flowers hold up well in humid climates, but they are more susceptible to issues with fungus and rot when humidity levels are especially high.

Fertilizer

Spider plants require little if any fertilizer. In fact, overfertilization can lead to leggy plants.

When planting a spider flower in a container, however, you may want to give it some slow-release fertilizer to support its prolific blooming habits.

Pruning

Spider flowers don’t require a lot of pruning, but you can trim them back during their growing season if you want to encourage bushier (rather than taller) growth.

Deadheading is not necessary and may be difficult since you can't simply pinch off the top. If you like, you can trim off dead or damaged leaves by using sharp shears to snip them at the place where they join the stem. Some older varieties of spider flowers may lose their lower foliage as they mature. Disguise those bare stems, if you like, by placing shorter species around the taller plant.

You can remove entire flower heads to prevent seeds from forming by cutting them off the stem. You can also cut the blooms to use as cut flowers if the smell is not offensive to you. To do so, cut the flowers to your desired length early in the morning and carefully remove the lower leaves from the stems (be cautious of the prickles and spines).  

Potting and Repotting

When growing spider flowers in containers, you may want to choose a dwarf variety to avoid the plant getting too top-heavy for its pot. You can plant seedlings in outdoor containers in April or May (depending on your climate) as the weather begins to warm and the danger of frost has passed. Choose a large pot and fill it with fresh, well-draining potting soil. Add your seedling to the center of the container and surround it with flowers that will fill around the edges of the pot or spill over it.

Make sure your container gets lots of full, direct sunlight and the soil stays consistently moist as the plants get established. You may need to water container-grown spider flowers more often than those grown in the ground. To encourage blooming, give your container-grown spider flower a dose of slow-release fertilizer during the growing season.

Repotting should not be necessary as spider flowers are annuals and will not last more than one growing season.

Pests and Problems

Spider flowers are surprisingly resistant to most pests and diseases. They are also largely ignored by rabbits and deer.

Spider flowers can have issues with leaf spot, downy mildew, powdery mildew, and dust if the plants are overcrowded or too wet. Make sure they have plenty of air circulation and avoid overhead watering if possible.

You may find the occasional cabbageworm or flea beetle dining on your spider flower's foliage or have issues with aphids, spider mites, or white flies—especially if your spider flowers are planted too close to each other or other plants.  

How to Propagate Spider Flower

Spider flowers propagate easily from seed, so other methods of propagation are, quite frankly, unnecessary.

You can harvest seeds from a healthy spider flower plant (if it is not a sterile hybrid) by allowing the seed pods to dry and turn slightly brown. If you choose this method (rather than allowing the plant to self-seed) you will only have a couple of days to harvest them before the seed pods pop open and spill their seeds. Once you’ve collected the seed pods, remove the seeds and allow them to dry completely on a paper towel or plate (approximately 5 to 7 days). You can store them in an airtight container until the following spring. It should be noted that if you harvest seeds from a nursery-grown spider flower, the offspring plants may not look and perform the same as the parent plant.

To grow your spider flower plant, sow the seeds directly into the ground in late spring or start them indoors approximately 6 to 8 weeks before the last frost. Fill growing pots or a growing tray with moistened potting soil and place the seeds on the surface of the soil, pressing them down gently, but not fully into the soil. Place the tray or grow pots in a plastic bag and then put the bag in an area that gets 8 hours of warm, direct sunlight each day. If the soil is moist enough and the bag is properly sealed, you shouldn’t need to water your seeds again until they germinate (but be sure to add moisture if the soil dries out).  

You will need to create a fluctuation of temperatures (65 to 70 degrees at night and 75 to 80 degrees during the day) to germinate the seeds. You can create this artificially with a heating mat or a small space heater placed a safe distance from the bag.

Transplant your seedlings outdoors (after hardening them off for a few days) when the seedlings are approximately 3 to 4 inches tall and there is no more danger of frost.

Types of Spider Flower

Much of the breeding work in recent years has focused on shrinking spider flower's substantial height. These new shorter varieties are better suited to containers, as well as the front or middle of the garden.

'Helen Campbell' spider flower

Cleome 'Helen Campbell' bears pure white flowers on tall, 4-foot stems.

'Queen Series' spider flower

Cleome 'Queen Series' offers a mix of rose, violet, and white flowers on 4-foot-plants.

'Senorita Rosalita' spider flower

Cleome 'Senorita Rosalita' bears lavender-pink flowers on a more heat-resistant 4-foot-tall plant.

'Violet Queen' spider flower

Cleome 'Violet Queen' produces lavender-purple flowers on 4-foot-tall plants.

Spider Flower Companion Plants

Cosmos

You can depend on this cottage-garden favorite to fill your garden with color all season long. The simple, daisy-like flowers appear in cheery shades on tall stems that are great for cutting. The lacy foliage makes a great backdrop for shorter plants, as well. Cosmos often self-seeds in the garden, so you may only have to plant it once—though the colors can appear muddy or odd in offspring plants. Sow cosmos seeds directly into the ground in spring or start with established seedlings. Avoid using fertilizer or overly rich soil as both can cause the foliage to grow large and lush while discouraging blooms. Cosmos does best with average moisture but will tolerate drought.

Moonflower

Moonflower is one of the most romantic plants you can grow and it can be found as an established plant in many garden centers. It's an ideal twilight-garden plant that bears large trumpet-shaped flowers that unfurl in the evening (or on overcast days) and stay open until the sun rises. Some are sweetly fragrant when open. This beautiful plant, like the spider flower plant, is also very heat- and drought-resistant. Plant it outdoors after all danger of frost has passed and give it moderate moisture and fertilizer. You can also train it into a treelike plant along a stake, especially in a large container. It should be noted, however, that moonflower and moonflower seeds are considered toxic to both humans and animals.

Zinnia

Want fast color for just pennies? Plant zinnias! A packet of seeds will fill an area with gorgeous flowers in an amazing array of shapes and colors—even green! And it will happen in just weeks. There are dwarf types of zinnias, tall types, quill-leaf cactus types, spider types, and multicolor blooms. You can also get special seed blends for cutting, special blends for attracting butterflies, and more. Zinnias are so highly attractive to butterflies that you can count on having these fluttering guests visiting your garden every afternoon. To make your garden irresistible, plant lots of tall red or hot pink zinnias in a large patch. 'Big Red' is especially nice for this with blooms that are outstanding and excellent for cutting. Zinnias grow quickly from seed sown right in the ground and do best in full sun with dry to well-drained soil.

Garden Plans for Spider Flower

Tiny Corner Garden Plan

Give your front yard almost instant curb appeal with this small, colorful garden plan. It includes other pollinator-friendly plants like flowering tobacco, butterfly bush, cosmos, and zinnias.

Moon Garden

A moon garden, or twilight garden, is designed to be enjoyed at night. The white blooms of these garden plans take on an ethereal glow and the air fills with the fragrance of night-bloomers like moonflowers, four o’clocks, and angel’s trumpets.