Mexican Petunia: Learn Ruellia Brittoniana Growing and Care

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Ruellia brittoniana, more commonly known as Mexican Petunia belongs to the Acanthaceae family and Ruellia genus.

As the name suggests, this plant is native to Mexico.

Purple flower of Ruellia Brittoniana Pin

However, it is also found abundantly in the Caribbean and South America.

Over the years, the plant has been known by multiple names, including Ruellia angustifolia (Nees) Lindau, and Cryphiacanthus angustifolius Nees, among others.

Several common names include:

  • Purple ruellia
  • Mexican bluebell
  • Hardy petunias
  • Purple showers

Today, the most widely accepted names for this species include Ruellia brittoniana and Ruellia simplex.

However, most people prefer to call it Mexican petunia. But it is not a petunia.

Two other varieties with variegation are Ruellia Makoyana and Ruellia portellae.

It’s an evergreen perennial known for its flowers and being deer resistant.

These plants typically form colonies of stalks with lance-shaped leaves.

While the foliage is attractive, it’s the Petunia flower that steals the show for this plant.

Other plants from the family Acanthaceae:

Ruellia Brittoniana Quick Care Tips

  • Botanical Name: Ruellia Brittoniana
  • Common Name(s): Mexican Petunia, Britton’s Wild Petunia, Purple ruellia, Mexican bluebell, Hardy petunias, Purple showers
  • Synonyms: Ruellia Tweediana, Ruellia Malacosperma
  • Pronunciation: Ru-EL-lee-a brit-toe-nee-A-na
  • Family & Origin: Acanthaceae family, native to Mexico
  • Growability: Easy to grow
  • Grow Zone: 8-11
  • Size: Grows up to 3′ -6′ feet tall and wide
  • Flowering: Blooms petunia-like flower from early summer to fall
  • Light: Full sun to partial shade
  • Humidity: Thrives in humidity
  • Temperature: Between 72° and 76° degrees Fahrenheit
  • Soil: Well-draining soil
  • Water: Water regularly, but do not overwater
  • Fertilizer: Fertilize with a tablespoon of 10-10-10 fertilizer
  • Pests & Diseases: Susceptible to spider mites and whiteflies and can be affected by root rot if overwatered
  • Propagation: Propagate through seeds, stem cuttings, or rhizome division
  • Plant Uses: Used as a border plant, in containers, or as a ground cover. Attracts butterflies and hummingbirds.

Mexican Petunia Care

Size and Growth

This low shrub has a dark purple cast and dark green leaves.

Mexican petunia plants have a fast growth rate, quickly reaching 3′ -6′ feet tall and the same in diameter.

Keep in mind that while purple baby showers may not be full, the plant becomes lush with age and from clumping colonies.

Owing to its fast-growing nature, it is considered to be invasive.

NOTE: Although it is listed as an invasive species, we’ve grown them for years in the state of Florida landscape and never experienced the plants getting out of hand.

The leaves of this plant can elongate up to 12” inches. However, when grown in dry conditions, the leaves usually remain short.

Flowering and Fragrance

The petunia ruellia is a flowering plant with lovely petunia flowers, usually lavender in color.

Each petunia-like flower lasts about one day, but the flowering season is considerably long, lasting from early summer to fall.

Moreover, the trumpet-shaped flowers grow in abundance.

Neither the blooms nor the plant itself has a distinctive fragrance. Nonetheless, it does manage to attract bees, butterflies, and even hummingbirds to the garden.

Light and Temperature

Purple showers love full sun but grow well in partial shade. The more sunlight they receive, the more flower they produce. 

They also grow well in places where they receive bright, indirect light and prefer high heat.

It thrives in temperatures between 72° and 76° degrees Fahrenheit.

These plants enjoy summer warmth and even survive a drought in warm climates.

However, they don’t do well in the cold. As temperatures start to drop, it is best to move Mexican petunias out of the way of the cold and chilly winter breeze.

Ruellia is recommended for USDA hardiness zones 8-11.

Watering and Feeding

Mexican petunia plant is very hardy and able to survive drought and flooding. Once established, this plant becomes drought-tolerant.

The best approach is to water just enough to keep the soil consistently moist.

While these plants are sturdy and can go without water for a long time, young petunia ruellia simplex needs regular watering.

During the colder months of the year, refrain from overwatering and only wet when the soil is visibly dry.

Purple ruellia plants also thrive in humidity, making them tolerant of frequent rains and boggy soil conditions.

These plants grow well without an additional boost of fertilizers. If you still want to feed your plants, a tablespoon of 10-10-10 fertilizer is enough.

Scatter the fertilizer around the plant during the flowering season.

Soil and Transplanting

Once established, these plants thrive and flourish in almost any type of soil.

For optimal growing conditions, use well-draining, fertile soil. Also, consider the pH level of the soil.

These plants tolerate alkalinity but usually do great in neutral or slightly acidic soil.

Transplant during early spring when the temperature is warm enough to allow the plant to settle and grow.

Grooming and Maintenance

Under the right conditions, these plants are pretty self-sufficient and do not require much additional care.

Since they are invasive, it is best to keep an eye on the growth.

NOTE: Mexican Petunia spread freely by rhizomes. Maintain control by choosing non-invasive cultivars.

If you feel that these purple flowers are taking over your garden, pull out some of the stems.

This plant is often unruly.

Make sure to prune regularly to keep plants in shape and maintain an appealing appearance. Also, don’t forget to clip the burned or damaged leaves.

Dwarf Ruellia ‘Katie’ has beautiful blooms along with easy care, and that is why Texas A&M University named it a Texas Superstar.

purple showers RuelliaPin

How to Propagate Petunia

This plant can self-seed aggressively.

During the rainy season or when hosed with water, the seeds can be ejected up to 10′ feet away.

It propagates well on its own through seeds started in pots. These plants also propagate through cuttings.

If you can’t have enough of the lovely violet flowers, cut the stem halfway down just below a node once the flowering season ends. Then dip the cut end into the rooting hormone.

The plant will replace the lost stem by growing multiple stems and flowers!

Mexican petunia can also be propagated via rhizome division. All you need to do is gently dig around the plant, loosening the soil. Then, slice through the rhizomes using a shovel to create multiple separate plants.

Mexican Petunia Pest or Diseases

Mexican petunia usually does not encounter any serious problems. However, cold weather can damage the plant, turning the leaves brown.

The only way to avoid this from happening is to protect the plant from cold. If the temperature is low enough to cause frosting, move the plant indoors (if possible) to a warmer spot.

Although it is not common for this plant to get infected, the Mexican petunia flower is susceptible to spider mites and whiteflies.

Spray a good-quality insecticide or a soap solution on the foliage to get rid of spider mites. Keep the problem under control by pruning the infected leaves, flowers, and stems.

Suggested Mexican Petunia Uses

The Mexican petunia is a beautiful plant bearing lovely flowers growing in full sun or partial shade. However, this spreading perennial is invasive and banned in some states.

In fact, R. brittoniana spreads by rhizomes and is self-seeding. It has become naturalized in South Carolina, Texas, and Hawaii. [source]

If you are worried about Mexican petunia taking over your yard, it is a good idea to get an infertile plant, which is unable to self-seed, from a nursery.

This is a plant that attracts butterflies, makes good border plants or ground cover, and adds winter interest when growing in South Florida.

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