// SPECIES PROFILE · ANNUAL · NON-NATIVE / NON-INVASIVE

Zinnia

Zinnia elegans

Zinnia (Zinnia elegans) is the cut-flower-and-butterfly garden workhorse — a tender annual native to the highlands of central Mexico, direct-sown after frost in NE Oklahoma, blooming continuously from July through hard October frost in nearly every color except blue. Consistently ranked among the top three annual nectar plants for butterflies in published pollinator-garden trials, and one of the most reliable cut-flower crops for the southern plains.

// QUICK FACTS

Family: Asteraceae — aster/composite family
Group: Annual — tender warm-season
Native range: Highlands of central Mexico (Chihuahua, Durango, Coahuila, Aguascalientes)
USDA hardiness: Frost-tender annual; killed by first hard freeze
Mature size: 1–4 ft tall (cultivar-dependent) × 1–2 ft wide
Sun: Full sun — non-negotiable
Soil: Average to fertile, well-drained
Water: Moderate; drought-tolerant once established
Bloom: July through hard frost with deadheading
Pollination: Butterflies (top tier), bees, hummingbirds, hoverflies
Invasiveness: Non-invasive — does not naturalize in N. American climates
Best uses: Cut flowers, butterfly garden, vegetable-garden border, mass color

Zinnia (Zinnia elegans) — *Zinnia elegans*. Photo via Wikipedia / Wikimedia Commons.

Identification

[ field key — habit · foliage · flowers/fruit · lookalikes ]

Habit

Erect single-stemmed or branched annual herb 1–4 ft tall depending on cultivar. Stems are stout, hollow, slightly hairy, with opposite leaf attachment. Cultivars range from compact bedding forms (8–12 in) to tall cut-flower selections (3–4 ft). Strongly upright habit; rarely needs staking.

Foliage

Opposite, simple, ovate to lance-shaped leaves 2–5 in long, slightly rough-textured, mid-green, sessile (no petiole) and sometimes clasping the stem. Foliage is unremarkable but clean — the appeal is entirely in the flowers. Mid-summer powdery mildew on lower leaves is the most consistent foliage problem in humid Oklahoma summers.

Flowers

Composite flowerheads 1.5–5 in across, in nearly every color and shade except true blue — scarlet, crimson, orange, yellow, gold, pink, salmon, lavender, white, lime green, and bicolors. Modern doubled cultivars produce dense ball-shaped 'dahlia-flowered' or 'cactus-flowered' heads; classic single forms have a clean ring of ray florets around a yellow disk. Each bloom lasts 7–14 days on the plant; sequential bloom continues for 12–14 weeks with regular deadheading.

Lookalikes

Other zinnia species in the trade include Z. angustifolia (narrow-leaf zinnia — smaller flowers, narrower leaves, 'Crystal' and 'Star' series), Z. haageana (Mexican zinnia — small bicolor flowers, 'Persian Carpet' series), and various Z. elegans × Z. angustifolia hybrids ('Profusion' and 'Zahara' series — superior mildew resistance). All are non-native and non-invasive in our climate.

Habitat & Range in NE Oklahoma

Zinnia elegans is not native to North America. Its native range is the seasonally-dry high-elevation grasslands and oak-juniper woodland edges of central Mexico (Chihuahua, Durango, Coahuila, Aguascalientes), where it grows as a summer monsoon annual. The species was domesticated and bred in Europe in the 18th and 19th centuries (named in 1759 for German botanist Johann Gottfried Zinn) and has been a global garden staple ever since.

Critically, Zinnia elegans is not invasive in North American climates. As a frost-tender warm-climate annual it is killed outright by the first hard freeze, and its seed has poor cold-tolerance, so it does not naturalize beyond the garden. This makes it one of the few non-native annual flowers whose ecological footprint in the Tulsa region is essentially zero outside cultivation — while still providing high nectar value to native pollinators during its bloom window. A textbook example of an ecologically positive non-native ornamental.

Ecology & Wildlife Value

[ wildlife · pollinators · interactions · conservation ]

Top-tier butterfly nectar plant

Zinnia elegans consistently ranks in the top three annual nectar plants for butterflies in published trials by the Xerces Society, Mt. Cuba Center, and Penn State Extension. The flat broad landing platform of the composite head plus the abundant nectar in disk florets makes it a magnet for swallowtails (eastern tiger, black, pipevine, giant), painted lady, monarch, gulf fritillary, common buckeye, sulphurs, and skippers. A 10×3 ft zinnia row in a Tulsa vegetable garden will reliably support continuous butterfly activity all summer.

Bee & hummingbird visitors

Bumblebees, sweat bees, leafcutter bees, and honey bees all forage zinnia flowers, particularly the single-flowered cultivars (doubled forms have reduced nectar accessibility). Ruby-throated hummingbirds regularly visit the red and orange single-flowered cultivars throughout the summer breeding season. A useful late-summer nectar bridge before fall goldenrod and aster bloom takes over.

Cut-flower production

Among the most productive cut-flower crops for the southern plains. Tall cultivars ('Benary's Giant', 'State Fair', 'Oklahoma' series) produce 8–15 long-stemmed cut flowers per plant per season with successive sowings. Vase life: 7–10 days. Major commercial cut-flower crop and the workhorse of Tulsa-area farmer-market and CSA growers.

Companion planting in vegetable beds

Zinnia rows planted around or through vegetable beds attract beneficial pollinators that improve cucurbit and tomato fruit-set, and also support populations of predatory beneficial insects (hoverfly larvae, parasitoid wasps, predatory bugs) that suppress aphids and small caterpillars on neighboring crops. One of the most-recommended companion-planting flowers in regional vegetable-garden literature.

Powdery mildew is the only consistent problem. NE Oklahoma’s humid summer nights produce reliable powdery mildew on lower zinnia foliage by August. Mitigations: (1) plant the 'Profusion', 'Zahara', and 'Queeny' series — modern interspecific hybrids with strong mildew resistance; (2) space plants at the recommended distance (don’t crowd); (3) water at the base of plants only, never overhead; (4) accept some lower-leaf damage on tall cultivars and remove affected leaves — the bloom continues unaffected.

Horticulture & Care

[ siting · planting · maintenance · pests ]

When to plant

Zinnias are direct-seeded after the last frost in NE Oklahoma — typically mid-April in central Tulsa to early May in the Bartlesville/Pawhuska area. Soil temperature should be at least 60°F. Successive sowings every 3–4 weeks through mid-July maintain peak bloom into October. Transplants are also widely available but offer little advantage over direct seeding in our climate — zinnias resent root disturbance and direct-sown plants typically catch up to or surpass transplants by midsummer.

Planting & establishment

Direct-seed: after frost, when soil is warm. Sow 1/4 in deep; thin to final spacing when seedlings have 3–4 true leaves.
Sun: full sun — absolutely non-negotiable for strong bloom.
Soil: average to fertile, well-drained; tolerates a wide pH range.
Spacing: 9–12 in for compact cultivars; 12–18 in for tall cut-flower forms. Adequate spacing reduces powdery mildew significantly.
Water: 1 in per week from rainfall + irrigation; water at the base only — overhead watering invites mildew.
Mulch: 2–3 in to retain soil moisture and suppress weeds.
Fertilizer: light side-dressing of balanced fertilizer at first flowering boost; do not over-fertilize.

Pruning & deadheading

Pinch the central terminal bud of young plants when 6–8 in tall to promote branching and a fuller plant with more lateral flower stems. Deadhead spent blooms regularly — cut back to the next set of leaves with a flowering bud. Continuous deadheading is the single most important practice for season-long bloom: let the plant set seed and bloom slows or stops.

Notable cultivar series

Pests & diseases

Powdery mildew — the consistent issue; choose resistant hybrid series and provide spacing/airflow.
Bacterial leaf spot in wet years — remove affected leaves; rotate locations annually.
Japanese beetles can defoliate tall cultivars in midsummer — hand-pick or accept some damage.
Spider mites on drought-stressed plants — correct watering practice.
Deer-resistant (rarely browsed); rabbits occasionally nip seedlings.

Cultural & Material Uses

Zinnia has a fascinating cultural history — nearly forgotten in its native Mexican range until European botanical collectors rediscovered it in the 1700s, then transformed by 19th- and 20th-century plant breeders into one of the most-bred annual flowers on earth.

Pre-Columbian Mexican use: Cultivated by the Aztecs for ornamental and minor medicinal use; reportedly considered an ugly, weedy flower (the Aztec name cimatlhuxochitl translates roughly as 'eye-sore'). The dramatic appearance change came only after centuries of European selective breeding.
European introduction & breeding: Spanish missionaries collected seed in the 1500s; reached European gardens by the 1600s. Named in 1759 for the German botanist Johann Gottfried Zinn (1727–1759), professor at Göttingen. Doubled forms appeared in the 19th century; the modern 'giant' types were developed by Burpee and other US seed houses through the 20th century.
Modern plant breeding: Among the most-bred annual flower genera; the Profusion and Zahara interspecific hybrids (Sakata, late 1990s onward) are landmark achievements in heat- and disease-resistant bedding plants — multiple All-America Selections winners. Continue to be a focus of professional breeders worldwide.
Indiana state flower & cultural symbolism: Zinnia elegans is the official state flower of Indiana (designated 1957). Often featured in Mexican Day-of-the-Dead and Catholic harvest-festival arrangements. The Pueblo of Acoma and other southwestern Indigenous nations use related Zinnia grandiflora for religious and dye purposes.
Cut-flower industry: Major commercial cut-flower crop globally; foundational species of the regional specialty cut-flower movement (Lisa Mason Ziegler, Erin Benzakein/Floret) that has revitalized small-farm flower production across the US since 2010. Key crop for Tulsa-area farmer markets and flower CSAs.
Garden-history note: President Thomas Jefferson grew zinnias at Monticello; documented in his garden notebooks. Has been continuously in commerce in the US for over 200 years.

Sources & Further Reading

USDA NRCS PLANTS Database — Zinnia elegans: https://plants.usda.gov/plant-profile/ZIEL
Lady Bird Johnson Wildflower Center — Zinnia notes.: https://www.wildflower.org/plants/
Missouri Botanical Garden Plant Finder — Zinnia elegans: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=287183
All-America Selections — Zinnia AAS winners (Profusion and Zahara series).: https://all-americaselections.org/
Mt. Cuba Center — pollinator-trial reports including zinnias as butterfly nectar plants.: https://mtcubacenter.org/research/trial-garden/
Xerces Society — pollinator-friendly plants of the southern plains.: https://xerces.org/pollinator-conservation/pollinator-friendly-plant-lists
OSU Extension — annual flowers and cut-flower production for Oklahoma.
Sakata Seed America — Profusion and Zahara breeding history.
Wikipedia — Zinnia elegans: https://en.wikipedia.org/wiki/Zinnia_elegans

Photos courtesy of Wikimedia Commons contributors under their respective licenses.

Companion Planting

[ guild · polyculture · cross-layer pairings ]

In a kitchen-garden polyculture, zinnia pairs naturally with: american persimmon (Diospyros virginiana), american beautyberry (Callicarpa americana), maypop / passionflower (Passiflora incarnata), comfrey (Symphytum officinale), cosmos (Cosmos bipinnatus), and black cherry (Prunus serotina).

In a polyculture bed, zinnia pairs with the partners above for pest deterrence, pollination, and soil-building.