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.
Better fit now and in 2050
Now: well-suited
2050: well-suited
Better fit now and in 2050
Now: well-suited
2050: well-suited
Better fit now and in 2050
Now: well-suited
2050: well-suited
Better fit now and in 2050
Now: well-suited
2050: well-suited
Similar plants
Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.
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.






