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Large white petunia

Large white petunia

Petunia axillaris
Large white petunia is the wild South American species behind the garden petunia: a loose, spreading annual or tender perennial in the nightshade family (Solanaceae), native to the grasslands and rocky outcrops of Uruguay, southern Brazil, Paraguay, Bolivia and Argentina. Its pure white, funnel-shaped trumpets, 1 to 3 inches long, are the only white flowers in the genus, and they release a strong scent at night that draws hawkmoths. The garden petunia (Petunia x atkinsiana) is a hybrid of this species and Petunia integrifolia, but grown as itself it is a taller, looser, fragrant plant for the evening garden rather than a compact bedding mound. It is frost-tender: the RHS rates it H3, half-hardy to a winter minimum of 23°F to 34°F, which the RHS equates to USDA zones 9b/10a, so it lives through the winter outdoors only in mild gardens and is grown from seed as a warm-season annual below zone 9b.
Climate fit: narrow (4/100)
Border
Container
Filler
Light
Full sun
Water
Moderate water
Mature size
1.6-3.3 ft tall · 11.8" apart
Life cycle
True annual (one season)
Native in Illinois
No
An ornamental in the nightshade family (Solanaceae) grown for its scented flowers.

Cold hardiness

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.
Now
Zone 6b
Plotwright
USDA Zone 6b
-5°F to 0°F
Won't grow here
Zone 7a
Plotwright
0°F to 5°F
Won't grow here
In plain terms: This location has cold winters. Its winters are projected to keep warming through 2050.
✕
Out of range today and still out of range in 2050.

Heat tolerance

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.
Loading AHS heat-zone data for this location...

Where this plant fits

Suitable across 2 ecoregions - 2 climate-resilient through 2070. Best matches first.

Plant this, not that

Better fit for this place
For Chicago, IL, these are replacement suggestions: similar plants with a stronger hardiness fit now and/or in 2050.

Similar plants

Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.
Common zinnia (Zinnia elegans) shown head-on as a fully double orange flower, the central disc florets curled into a tight yellow spiral.
Zinnia elegans
Common zinnia
An old garden-favorite annual native to Mexico, grown for showy daisy-like flowers in nearly every color but true blue - red, yellow, orange, pink, rose, lavender, green, and white. Bushy, leafy plants rise on upright, hairy, branching stems and bloom continuously from early summer to frost. A magnet for butterflies and hummingbirds, and one of the most reliable cut-and-come-again cutting-garden flowers.
Annual
Full sun
Moderate water
Zones 2a-11b
Climate: moderate
Border
Filler
Pollinator
Container
Jasmine tobacco (Nicotiana alata) - three white, five-pointed star-shaped flowers on slender tubes against a blurred green background.
Nicotiana alata
Jasmine tobacco
Jasmine tobacco, also sold as flowering tobacco, sweet tobacco, or winged tobacco, is a tender perennial in the nightshade family (Solanaceae) native to southern and southeastern Brazil, Paraguay, Uruguay, and northeastern Argentina. The true species grows 3 to 5 feet tall from a low rosette of large, hairy basal leaves with winged stalks, and from early summer to frost it carries long-tubed, star-faced flowers, white to greenish-yellow, that open in the evening and pour out a sweet scent through the night for moths. It is perennial only in USDA zones 10a-11b, so most gardeners grow it as a summer annual. Many plants sold as 'flowering tobacco' are compact hybrids (Nicotiana × sanderae and similar strains) up to 24 inches tall whose flowers open by day and are mostly unscented; for the night fragrance, grow the species from seed. Be aware that it is poisonous: every part of the plant contains nicotine, it is harmful if eaten, and the RHS advises gloves when handling it.
Annual
Full sun / Part shade
Consistent moisture
Zones 10a-11b
Climate: narrow
Border
Filler
Container
Pollinator
Annual vinca (Catharanthus roseus) as a dense, low mounding bedding mass smothered in flat five-lobed pink flowers above glossy dark-green leaves.
Catharanthus roseus
Annual vinca
A tender perennial from Madagascar grown across temperate North America as a heat-loving summer annual - a mounding 6-18 inch plant in the dogbane family covered in flat five-lobed phlox-like flowers from June to frost. The species blooms rosy-pink to red with a darker mauve throat, and it shrugs off the hot, humid weather that wilts most bedding plants. Every part of the plant is poisonous: it is the natural source of the vinca alkaloids used in chemotherapy.
Annual
Full sun / Part shade
Moderate water
Zones 10a-11b
Climate: narrow
Border
Filler
Container
Flossflower (Ageratum houstonianum) - fuzzy thread-like flower clusters, soft blue-lavender coloring, low mounding clumping habit, toothed heart-shaped leaves.
Ageratum houstonianum
Flossflower
A compact, frost-tender warm-season annual from Mexico and Central America grown for its dense, fuzzy, thread-like ("flossy") flower clusters - most famously in soft true blue and lavender-blue, the trait that sets it apart from almost every other bedding annual, plus pink and white forms. It mounds into a clumping cushion 6 to 12 inches tall and about as wide, blooming from early summer until frost over soft, heart-shaped, slightly hairy leaves. It is easy and rewarding bedding, edging, and container color in full sun to part shade with steady moisture, but it is strictly look-don't-eat: the foliage and stems contain hepatotoxic pyrrolizidine alkaloids and are toxic if ingested.
Annual
Full sun / Part shade
Consistent moisture
Zones 2a-11b
Climate: moderate
Border
Container
Filler
French marigold (Tagetes patula) in bloom showing upright bushy habit with mahogany-and-gold bicolor flowerheads, buds, and finely divided pinnate toothed foliage.
Tagetes patula
French marigold
A compact, fast warm-season annual from Mexico and Guatemala (despite the "French" name) grown as bedding, edging, and container color. It typically reaches 6 to 12 inches tall with single to fully double, 1-2 inch fragrant flowerheads in yellow, orange, red, and bicolor over aromatic, deeply pinnate toothed foliage. Blooms June to frost in full sun, is low-maintenance, and is one of the few annuals deer tend to leave alone. On the name: Kew and GBIF now both fold the French marigold into Tagetes erecta, the African marigold, and treat Tagetes patula as a synonym of it. The two are still sold and bred as distinct garden plants, so this page keeps the familiar name.
Annual
Full sun
Moderate water
Zones 2a-11b
Climate: moderate
Border
Container
Filler
Globe amaranth (Gomphrena globosa): many round, clover-like magenta flower heads on upright stems among oval green leaves.
Gomphrena globosa
Globe amaranth
Globe amaranth is a warm-season annual in the amaranth family (Amaranthaceae), grown for its round, clover-like flower heads of papery, long-lasting bracts: bright magenta in the species (Missouri Botanical Garden PlantFinder), with cultivars in purple, pink, red, lilac, violet, and white. The true flowers are tiny white to yellow trumpets tucked among the bracts. Kew's WCVP gives its native range as Mexico, Central America (Guatemala, Honduras, Nicaragua, and Panama), and tropical South America (Colombia, Ecuador, Guyana, Bolivia, and Brazil). NC State Extension and Missouri Botanical Garden describe a compact, upright plant 6 to 24 inches tall and 6 to 12 inches wide that flowers from June until frost, takes heat and drought once established, and makes a classic everlasting: the heads keep their color when cut and dried. It is frost-tender. NC State Extension rates it winter hardy only in USDA zones 9 to 11, where it can be grown as a perennial; everywhere else it is sown or planted after the last frost and grown for a single summer, which is why both sources list it as an annual for zones 2 to 11. It is a Gomphrena, not an Amaranthus: the amaranth in its name is the family it shares with love-lies-bleeding and the grain amaranths. It also shares the name bachelor's button with the cornflower (Centaurea cyanus), a different plant.
Annual
Full sun
Moderate water
Zones 2a-11b
Climate: moderate
Border
Filler
Container
Pollinator

Educator packet

Plant packet
Large white petunia educator packet
Large white petunia is the wild South American species behind the garden petunia: a loose, spreading annual or tender perennial in the nightshade family (Solanaceae), native to the grasslands and rocky outcrops of Uruguay, southern Brazil, Paraguay, Bolivia and Argentina. Its pure white, funnel-shaped trumpets, 1 to 3 inches long, are the only white flowers in the genus, and they release a strong scent at night that draws hawkmoths. The garden petunia (Petunia x atkinsiana) is a hybrid of this species and Petunia integrifolia, but grown as itself it is a taller, looser, fragrant plant for the evening garden rather than a compact bedding mound. It is frost-tender: the RHS rates it H3, half-hardy to a winter minimum of 23°F to 34°F, which the RHS equates to USDA zones 9b/10a, so it lives through the winter outdoors only in mild gardens and is grown from seed as a warm-season annual below zone 9b.
Scientific name
Petunia axillaris
Plant type
annual
Hardiness
9b-10a
Light
full-sun
Moisture
moderate
Spacing
11.8"
Classroom prompts
- Which plant traits are observations, and which are care recommendations?
- How would this plant fit change if the garden location moved warmer, colder, wetter, or drier?
- Which source-backed facts would you cite in a lesson handout?
Use the Sources & citations section below for page citation styles and the field-level source list.

Sources & citations

Cite this page
For lesson plans, articles, or research that uses this page. Use the source cards below to explore the references that informed this record.
Plotwright. (2026, May 17). Large white petunia (Petunia axillaris). Retrieved 2026, October 9, from https://plotwright.com/plants/petunia-axillaris
Sources used for this record
This record is compiled from the sources below.
RHS Find a Plant
Botanical research database
Plants of the World Online (POWO)
Botanical research database
Flora e Funga do Brasil
Botanical research database
GBIF
Botanical research database
Wikipedia (ecoregion articles)
Botanical research database
USDA PLANTS Database
Government data source
Wikimedia Commons
Photo · CC BY-SA 4.0
Scientific Reports
Botanical research database
RHS Find a Plant
Botanical research database