Mexican Petunias: Self-Seeder Plant But Beware


Mexican Petunia

Each growing season, the Mexican petunia, or ruellia, becomes more popular. Commercial landscape plants usually enthrall homeowners.

This spring, as you pace the aisles of your garden center, wondering what to buy for color and which partner to choose, think about the iridescent blue of Mexican petunias.

Besides enduring high heat and humidity, it also performs well in drought conditions Despite its name, ruellia is not related to petunias.

Petunia belongs to the Solanaceae family, which includes tomatoes, peppers, and eggplants.

Mexican Petunia Genus

The Ruellia is a member of the Acanthaceae family, including shrimp plants and black-eyed Susan vines.

Ruellia plants have bluish-purple flowers that radiate color. Even though Purple Showers are mostly sold generically, they are becoming more popular.

Chi-Chi Pink, which reaches 36 to 48 inches in height and spreads 18 inches, is another pink-flowered variety.

Katie, for example, is a shorter variety. Their height is only 8 to 12 inches, and their spread is 12 to 24 inches.

It is best to grow Ruellia in full sun, but I have seen some remarkable plants in partial shade.

Moisture-rich, well-drained, organic-rich soils are ideal for the Mexican petunia but can also thrive on poor soils.

Combinations work well with the deep green foliage with hints of burgundy.

Large leaves can be almost a foot long, narrow, and pointed, depending on the variety. Clusters of flowers are borne on forked branches.

A tubular or funnel-shaped flower can reach a length of 2 inches. The long bloom period is usually early summer and lasts through fall.

Care for Mexican Petunias

This hardy plant can be grown almost anywhere if the temperatures are warm enough.

These plants can grow in dry and bog areas, which are heat, humidity, flood, and drought tolerant.

As long as you water and deadhead them occasionally, these plants don’t require much attention once they’ve been established.

In addition to being disease resistant, Ruellias sometimes suffer from spider mite problems.

The Best Way to Grow Mexican Petunias From Seed

It is also possible to propagate Mexican petunias from seed.

How to do it:

  1. Seeds should be planted in starter pots with moist, rich potting soil. Cover the seed gently with the soil. 
  2. Ensure that the pots are placed in a warm area that receives bright, indirect light. 
  3. Ensure that the soil is moist by checking it every day. 
  4. Within ten days, germination should occur. 
  5. Harden off the seedlings when they are several inches tall to acclimate them to the outdoors. 
  6. Move them outside as soon as the seedlings are acclimated to the full sun. 

Mexican Petunias: Potting and Repotting

Potted Mexican petunias are an ideal option for those living in areas with cold winters since they can be moved around. 

Mexican petunias, however, need to be repotted frequently due to their rapid growth rate. 

Ensure the new pot is at least 2 inches larger than the current one. Set the plant into the new pot after gently removing it from its pot. 

Put well-draining, fertile soil in the pot and bury the root system to the same depth. Be sure to water thoroughly. 


Mexican petunias do not require special winter care when grown in warmer climates with mild winters.

Whenever the soil feels dry, reduce watering. 

Mexican petunias cannot handle cold temperatures, so if they threaten your area, move them indoors. 

Mexican Petunias: How to Make Them Bloom

These Mexican petunias are known for their petunia-like, purple, trumpet-shaped flowers. 

The blooms die off quickly, but Mexican petunias continue to produce their vibrant blooms for quite some time, usually from late summer to the end of the season. Aromatically, they are not very strong. 

Pruning the plant after blooming encourages flower production. To encourage new growth, cut down the flowering stems. 

Make room for new blooms by deadheading the spent blooms. Make sure the Mexican petunia receives plenty of sunlight to ensure abundant blooms. 

The most frequent Mexican petunia problems

It is hard to kill Mexican petunias, and they can withstand droughts, floods, and high temperatures. 

Many gardeners have encountered problems with these plants, despite their hardiness. Brown leaves are a common problem.

Brown Leaves

Brown leaves indicate your plant has been damaged by cold weather.

Moving the plant to a warmer location is recommended, and the damaged leaves should be removed. 

Warmer temperatures will allow the plant to regrow full and lush.  

Word Of Advice

The Mexican petunia is a fast grower and spreader. In just a few years, they can quickly overtake native flora due to their ability to reseed themselves. 

In Florida, they are considered invasive by the University of Florida.