Mexican petunia (Britton’s wild petunia) Ruellia simplex
Mexican petunia (Britton’s wild petunia) (Ruellia simplex) is an evergreen perennial flowering plant in the Acanthaceae family, native to Mexico to Argentina and the Caribbean. It grows 30 cm–1 m (12 in–3.3 ft) tall and 40–90 cm (16–35 in) wide, wants full sun and moderate water, and is hardy to about -4 °C (25 °F). Space plants about 40 cm (16 in) apart.
Plan Mexican petunia (Britton’s wild petunia) in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Mexican petunia (Britton’s wild petunia) at a glance
| Type | Perennial flowering plant, evergreen |
|---|---|
| Family | Acanthaceae |
| Mature height | 30 cm–1 m (12 in–3.3 ft) |
| Mature spread | 40–90 cm (16–35 in) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance high |
| Soil pH | 5–8 |
| Cold hardiness | About -4 °C (25 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 40 °C (104 °F) |
| Flowering | from about April for 21–43 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Mexico to Argentina and the Caribbean |
| Common in gardens of | 🇹🇭 Thailand, 🇸🇬 Singapore, 🇲🇾 Malaysia, 🇺🇸 United States, 🇲🇽 Mexico, 🇧🇷 Brazil, 🇦🇺 Australia |
| Invasive in | US (Florida: Category I invasive; also Texas and Gulf states), Australia (Queensland, environmental weed): check local rules before planting |
Is Mexican petunia (Britton’s wild petunia) toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Not reported as poisonous.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Mexican petunia (Britton’s wild petunia)
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Mexican petunia (Britton’s wild petunia)
- How far apart should I plant Mexican petunia (Britton’s wild petunia)?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 40–90 cm (16–35 in).
- Does Mexican petunia (Britton’s wild petunia) need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Mexican petunia (Britton’s wild petunia) need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance high.
- How cold-hardy is Mexican petunia (Britton’s wild petunia)?
- It tolerates about -4 °C (25 °F) once established, roughly USDA zone 9.
- When does Mexican petunia (Britton’s wild petunia) flower?
- From about April for 21–43 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Mexican petunia (Britton’s wild petunia) poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Not reported as poisonous.
- What grows well with Mexican petunia (Britton’s wild petunia)?
- There is no well-documented companion pairing for Mexican petunia (Britton’s wild petunia). Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade A (A: strong evidence).
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
- UF/IFAS Extension tropical and subtropical fruit and landscape publications, University of Florida
- Florida Invasive Species Council plant list (Category I and II), Florida Invasive Species Council (formerly FLEPPC)
Notes and assumptions
- Narrow dark leaves on purple stems; each purple trumpet lasts a day. Thrives in wet ditches and pond edges as well as dry beds, which is why it escapes: grow sterile, non-seeding cultivars or a dwarf form, or a native alternative where it is invasive.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Black-eyed Susan vine Thunbergia alata
- White api-api Avicennia alba
- Firecracker flower (crossandra) Crossandra infundibuliformis
- Bear’s breeches Acanthus mollis
- Bengal clock vine (blue trumpet vine) Thunbergia grandiflora
- Nerve plant (fittonia) Fittonia albivenis
- Sunflower Helianthus annuus
- French marigold Tagetes patula