Pronounciation: COZ-mos bi-pin-NA-tus

Hardiness zones
Sunset All
USDA All

Landscape Use: Cosmos is a wonderfully cheerful accent and border plant for mixed flower gardens around the world. In hot, arid climates like Phoenix, cosmos can be grown through much of the year as a bedding plant in well-watered flower gardens. In cooler climates, cosmos is great as a summer annual for flower gardens and planters such as this one at the famous Rilla monastery in Bulgaria.

Form & Character: Stiffly upright and vigorous, bright, festive when flowering, stiff upright, tender, open and airy.

Growth Habit: Evergreen, herbaceous annual, grows to 2- to 4-feet tall depending on cultivated variety.

Foliage/Texture: Opposite, variable in length, medium dark green, pinnately cut; fine texture.

Flowers & Fruits: Brilliant white. pink, red to magenta ray flowers, solitary or in clusters, 2 inches in diameter with 8 petals and small yellow centers; fruits are achenes.

Seasonal Color: In Phoenix, flowers freely throughout the cool season.

Temperature: Tolerant of all but highest Phoenix summer heat (afternoons, western sun, temperatures above 110^oF). In Phoenix, cosmos will also grow throughout the cool season during those years when winters are warmer (which is about every winter now with the effects of the Phoenix urban heat island being so prevasive).

Light: Partial shade to full sun, but wholly intolerant of intense full western exposures.

Soil: Well-drained soil with some organic matter is best, tolerant of some alkalinity.

Watering: Regular supplemental water is absolutely required in Phoenix.

Pruning: Head back slightly after bloom to promote secondary blooms, otherwise no pruning is necessary.

Propagation: Easy by seed.

Disease and Pests: None

Additional comments: Cosmos can make a warm and unassuming addition to any irrigated, warm-season Phoenix landscape flower garden. There are many named cultivars of variable height (including dwarf) and red-hued flower colors that expand the ude potential of this wonderful bedding plant.

Taxonomic factoid: The genus Cosmos contains about 25 species of annual and perennial plant species.