Note that Mexican petunias are aggressive spreaders.
Theirunderground rhizomescan become difficult to manage in ideal growing conditions, and these plants also spread via seeds.
Confirm that there are no state or local ordinances prohibiting Mexican petunias in your region before planting.
The Spruce / Adrienne Legault
Mexican Petunia Care
Here are the main care requirements for growing low-maintenance Mexican petunias.
According to the University of Florida, they are considered invasive in Florida.
Soil
Mexican petunias are hardy, so they can typically survive in any key in of soil.
The Spruce / Adrienne Legault
However, if you want these plants to thrive, grow them in a well-draining, rich soil.
Temperature and Humidity
These tough plants are heat and drought-tolerant.
They thrive in areas with high humidity and high heat.
The Spruce / Adrienne Legault
Mexican petunias do not handle the cold well and are not frost-hardy.
Be sure to protect these plants if any cold weather comes your way.
Mexican petunias do need to be repotted often, however, because they grow so quickly.
The Spruce / Adrienne Legault
Be sure to bury the root system, then water thoroughly.
You will just need to reduce watering, and only water when the soil is completely dry.
Common Pests
Mexican petunia plants are not afflicted with any serious pests or diseases.
Simply pluck off the splotchy leaves on small infestations.
Use horticultural oils to eliminate the mites.
In warmer areas without frost, they can bloom all year.
What Does a Mexican Petunia Flower Look and Smell Like?
They do not have a strong aroma.
To encourage flower production, prune the plant after blooming.
Deadheading Mexican Petunias
Deadheadthe spent Mexican petunia flowers to make room for future blooms.
Their seeds lack any sort of dormancy, with no requirement for scarification or cold stratification.
This means that the seeds can germinate right away.
In this case, move the plant to a warmer area or indoors and remove the damaged leaves.
Your plant should bounce back once it’s receiving the warm temperatures it needs.
Mexican petunias are perennials so they will generally come back every year.
In areas with warm winters, this plant is evergreen.
For areas with cold winters, it is sometimes used as an annual.
There’s no place better or worse place to plant a Mexican petunia.
This hardy plant can be grown almost anywhere, as long as temperatures are warm enough.
Mexican petunias can be grown in both sun and partial shade, but prefer full sun.
More sunlight will encourage more flowering.
Mexican petunias spread and grow fast thanks to rhizomes and a prolific ability to reseed themselves.
Ruellia Simplex.University of Florida Center for Aquatic and Invasive Plants.
Ruellia simplex ‘Purple Showers’.
University of Florida Extension.
Ruellia simplex.North Carolina State University Extension.
