Annual
Spider Flower
Cleome hassleriana · Cleomaceae
Also called: Cleome, Grandfather's Whiskers, Pink Queen, Spider Plant (misnomer)
Spider Flower (Cleome hassleriana) is a low-water annual well suited to Tucson and the low desert. It grows to 3-5 ft tall and 1-2 ft wide in full sun, with a fast growth rate.
Spider Flower at a glance
- Water use
- Low (established)
- Sun
- Full sun (6+ hours); tolerates Tucson's intense sun well. Light afternoon shade acceptable in hottest weeks.
- Mature size
- 3-5 ft tall and 1-2 ft wide
- Growth rate
- Fast
- Bloom
- Airy clusters of pink, rose, lavender-purple, or white with long protruding stamens, Summer through fall (continuous bloom in heat; thrives through monsoon)
- Cold hardiness
- Frost-sensitive; killed by freeze. Grown as a heat-tolerant summer annual in Tucson 9a-9b.
- Soil
- Adaptable to most well-drained soils including lean, sandy, alkaline Tucson soils. Good drainage important.
- Native range
- Southern South America (southern Brazil, Argentina, Paraguay, Uruguay)
- Best used as
- Back-of-border height, Pollinator and moth garden, Cottage and cut-flower garden, Quick summer fill
- Wildlife
- Attracts bees, butterflies, and hummingbirds; night-blooming fragrance draws sphinx (hawk) moths. Strong pollinator value.
- Toxicity
- Generally regarded as non-toxic to pets and humans; not on the ASPCA toxic list. Note the stems have spines and the foliage is glandular/musky-scented—wear gloves when handling and discourage contact with sensitive skin.
How to grow Spider Flower in Tucson & the low desert
Watering
Warm-season annual: direct-sow or transplant after last frost (March-April). Water regularly to establish, then drought-tolerant—deep weekly watering suffices once rooted. Avoid waterlogged soil.
Fertilizer & nutrients
Light feeder; tolerates poor soil. A modest application of balanced slow-release fertilizer at planting is sufficient. Excess nitrogen reduces flowering and causes flopping.
Pruning & care
Deadhead to prolong bloom and limit prolific self-seeding. Tall plants may need staking. Remove at season's end.
Notes
Heat- and drought-tough summer annual that excels in Tucson's monsoon season when cool-season flowers are gone. Self-seeds aggressively—deadhead if you want to control spread. Plants have a distinctive pungent foliage scent and small thorns on stems.
Sources: University of Arizona Cooperative Extension; Pima County Master Gardeners; Missouri Botanical Garden