Zinnia (group)
Common Name: zinnia
Type: Annual
Family: Asteraceae
Zone: 2 to 11
Height: 0.50 to 4.00 feet
Spread: 0.50 to 1.50 feet
Bloom Time: June to frost
Bloom Description: All but blue and brown
Sun: Full sun
Water: Medium
Maintenance: Low
Suggested Use: Annual
Attracts: Birds, Hummingbirds, Butterflies
Tolerate: Black Walnut

Culture

Annual. Easily grown in humusy, evenly moist, well-drained soils in full sun. Sow seed directly in the ground after last frost date and, if desired, at 2-3 week intervals thereafter until the end of June to insure a good season-long bloom. For earlier spring bloom, start seed indoors 4-6 weeks before last frost date. Some varieties are widely available in cell/six packs from nurseries (small plants that have not yet flowered are best). Disease-resistant varieties are good selections for hot and humid summer climates such as the St. Louis area. Set out seedlings and purchased plants after last frost date. Pinch young plants to promote compact, bushy form. Good air circulation helps prevent onset of fungal leaf diseases. Deadhead spent flowers to promote additional bloom and maintain plant appearance.

Noteworthy Characteristics

Although the genus contains about 17 species of annual, perennial and low shrubs native to the southwestern U.S., Mexico, Central America and South America, it is the cultivars of several species that have for years been popular garden favorites featuring colorful daisy-like flowers over a long summer to fall bloom period.

Zinnia elegans (common zinnia) is perhaps the most widely grown species. Plants typically grow 1-3' (less frequently to 4') tall on upright, hairy, branching stems. They feature continuous summer to fall bloom in cool summer climates, but may slow down some at the peak of a typical St. Louis summer, particularly if attacked by fungal diseases. Many flower forms (single, semi-double, double, ruffled, dahlia, cactus or small pompoms) and flower colors (shades of red, yellow, orange, pink, rose, lavender, purple, green and white) are available. Sizes range from small-flowered dwarfs (to 6” tall) to large-flowered giants (to 4’ tall). Ovate to lance-shaped, opposite leaves (to 5” long) usually clasp the stems.

A large number of cultivars are commonly available, including:

Button Box Series (double flowers of dwarf and dahlia types to 12" tall)
Dasher Series (dwarf double flowers to 12" tall)
Dreamland Series
(large double flowers in dwarf and compact types to 12" tall)
Lilliput Series
(small double flowers to 18" tall)
Magellan Series
(compact double flowers to 14" tall)
Marvel Series
(large flowers to 18" tall)
Peter Pan Series
(large flowers of dwarf and compact type)
Phoenix Series
(small flowers to 18" tall)
Pinwheel Series
(double flowers)
Pulchino Series (double flowers to 15" tall)
Short Stuff Series
(dahlia type doubles to 10" tall)
Small World Series
(to 6" tall) and
Zesty Series
(doubles to 24" tall)

Zinnea angustifolia (creeping zinnia) is also widely grown. It features narrow-leaved plants that are commonly used for mass plantings, edging, naturalizing, containers and hanging baskets. Size ranges from dwarf cultivars (to 6" tall) to taller cultivars (to 3' tall). Flower colors include various shades of red, orange, yellow, lavender and cream.

Cultivars of interest include:
Cascade Beauties Series (white and yellow to 10" tall),
Crystal Series (compact to 10" tall) and
Star Series (star-shaped flowers to 14" tall).

Zinnia grandiflora (Rocky Mountain or prairie zinnia) features small narrow leaved plants to 6" tall with yellow-orange flowers. Swizzle Series (double bicolor flowers to 12" tall) is noteable.

Zinnea haageana (Haage's zinnia or Mexican zinnia) features narrow leaved plants to 2' tall with 1" diameter flower heads containing yellow rays and orange center disks. 'Old Mexico' and 'Persian Carpet' are noteable.

Z. elegans x Z. angustifolia hybrid known as the popular Profusion Series (2" diameter flowers on 15" tall plants in orange, salmon red and white with no powdery mildew problems).



Genus name honors Johann Gottfried Zinn (1727-1759), professor of botany, Gottingen.

Problems

Z. elegans is susceptible to powdery mildew, leaf spots, root rots and blights. Plants of Z. angustifolia generally have better disease resistance than those of Z. elegans. Watch for whiteflies, aphids, thrips, Japanese beetles and caterpillars.

Garden Uses

Mixed borders, beds, cottage gardens, cutting gardens and containers. Many are excellent fresh cut flowers.