Ruellia/Mexican Petunia Plant Care

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Ruellia Mexican Petunia with purple flowers

Ruellia or Wild petunias are easy to care, hardy, evergreen flowering plants that grow fast and spread fast (invasive) in the ground just like the mint plants. They self pollinate and keep on flowering. They are a great option for beginners, and a great choice for landscape ground coverage.


To grow ruellia / mexican petunia successfully, give it full sun, well draining soil and water frequently when it's young. Once established, it becomes drought tolerant. Mexican petunia's thrive in warm hot and humid climates, but are also frost resistant, super hardy and bounce back after winter passes away

Ruellia General Information


Mexico, the Caribbean, and South America


wild petunia,

mexican petunia

Ruellia simplex, a sterile cultivar,

chi chi (pink flowers),

icicles (white flowers),

baby katie

(foot long dwarf with purple flowers)

Flower shape

2 inch funnel shaped


Evergreen perennial




65°F to 90°F (18°C to 32°C), frost tolerant

USDA Zones

8b through 11

🌼Flowering season

Spring to Summer


Keep the soil moist at all times


Full Sun, Partial Shade


Well draining, and moist soil


seeds, cuttings, or root divisions


30 to 90 cm (11 to 35 inch)

How to Grow🌱

You can propagate ruellia from their seeds, cuttings, or root divisions. Germination temperature range is 70 to 75°F (21-24°C) so it’s ideal to germinate indoors. Transplant in the ground or a container, about 18 inches apart.

How fast does Ruellia grow

“Wild” Petunias spreads aggressively by self sowing or via rhizomes. You may want to keep this in mind if you are growing ruellias in the ground. Due to this self sowing, Ruellias are an ideal container plant.


Ruellias like regular watering, but are also drought tolerant once established. Water your Ruellia plant when the top 1-2 inches of the soil starts to dry.  Just touch the top soil, if it is dry and doesn’t stick your fingers, water your Ruellia plant.


If you live in a hot, dry, desert, arid or tropical climate, you will need to water Ruellia plants every day or even more than once to make sure the soil does not get too dry under full sun and keep the soil slightly moist in such climates.


During spring and winter months, you may need to water the plant just once a week. During the cooler days, the plant will very likely be dormant so you will need to reduce the frequency of watering as it does not need much water (or fertilizer) when dormant.


Ruellias have a penchant for warm temperatures and they need full sun exposure. 


If you live in a hot, dry, desert, arid or tropical climate, place the Ruellia in a location that receives shade from the afternoon sun. Keeping ruellias in shade and lack of sufficient sunlight would mean fewer blooms.

Ideal Growing Temperature🌡️

Ideal growing temperature for Ruellia is between 65°F to 82°F (18°C to 28°C) with relative humidity of 65 to 80%. They grow best in USDA Hardiness zones 8b through 11.


Although ruellias thrive in warm, hot and humid climates, they can survive frost conditions. They die back at the foliage tips if the temperatures are in the 30s (0 degrees C) and they die back all the way to the ground if the temperatures are in the 20s (-6 C). Once the temperatures get warmer, the plant bounces back well. As i said, ruella’s are “Super hardy” 💪


Ruellia needs rich, well draining and moist soil. So opt for a soil that is rich in compost or manure and does not hold water. One recommended soil mix is Soil + Sand/perlite with upto 30% of organic compost. Organic compost has a high amount of nitrogen so don’t add too much, else it will lead to more foliage and less buds.


If you live in a hot, dry, desert, arid or tropical climate, cover the soil with mulch (dead leaves, coco peat, or wood chips) to keep the soil temperature cool and avoid heating of exposed soil by the sun.


Since Ruellias are self seeding plants, pruning/trimming is essential if you want to control their rampant growth. You should also prune any frost damaged foliage.

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