Plant library · Annual Flowers
Cleome hassleriana
Cleome brings a tall, open layer to annual borders, reaching about 4 feet tall while keeping a relatively narrow 2-foot spread. Its spider-like summer flowers suit loose, cottage-style planting as well as more structured beds that need vertical lift behind lower growers. Use it where its airy outline can rise above the planting rather than crowd a tight foreground.
Place cleome toward the back or middle-back of an island bed, or alongside a fence where its upright stems can read clearly without blocking a path or a shorter planting. Leave a foreground band for lower annuals; this softens the view of the stems near ground level and gives the taller plants visual support. Avoid narrow foundation strips and path edges, where the flowering stems may lean into circulation space.[1][2]
Set plants 18 inches apart, center to center, for a connected vertical display. Each plant can finish about 2 feet wide, so reserve a broad planting zone rather than treating that spacing as a clear walkway allowance. Keep the first row back from paths and bed edges, and allow enough reach-in room for deadheading or removing plants at the end of the season.
Give cleome full sun in a warm, open position with well-drained soil. Its low-water needs make it more useful in a sunny bed than in a damp pocket that stays cold or wet after rain. Group it with other plants chosen for exposed, brighter conditions instead of placing it behind dense shrubs or in shade cast by structures.[1]
Flowering runs from summer into early fall, so reserve its space as a tall seasonal layer rather than relying on it for spring structure. Deadheading can extend the floral display and limit unwanted seedlings. Because it is an annual, plan for the bed to open up after frost and leave access for clearing and replanting.[1]
Expect cleome to be a substantial presence during its growing season, even when planted among smaller annuals. Seedlings are sensitive to transplant disturbance, so direct sowing or careful early transplanting helps keep the intended spacing intact. It can also reseed readily, making it better suited to beds where a few volunteer plants can be noticed and edited before they fill the gaps.[1][3]
Editorial content updated 2026-07-20.