Mexican petunia (Ruellia simplex)

Also known as: Texas Petunia, Mexican blue bells, Britton's wild petunia

Ruellia simplex, commonly known as Mexican petunia, is an evergreen perennial herb notable for its wrinkled, trumpet-like purple blooms. Originally grown as an ornamental plant, it has a robust spreading nature that has led to its naturalization beyond its native Mexico. This aggressive growth has caused it to be labeled as an invasive species in numerous countries.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting

Attributes of Mexican petunia

Lifespan

Perennial

Plant Type

Herb

Plant Height

91 cm

Spread

30 cm to 60 cm

Leaf Color

Green Purple

Flower Size

8 cm

Flower Color

Purple Lavender

Images of Mexican petunia

Quickly Identify Mexican petunia

Distinctive violet petunia-like flowers lasting one day, 2 inches (5 cm) in diameter.

Long, cylinder-like fruit capsules, 1 inch (2.54 cm) in length, with explosive seed dispersal.

Linear leaves, 6 to 12 inches (15 to 30 cm) long, dark green with purplish veins.

Stems up to 39 inches (100 cm) tall, branching from base with smooth texture.

Herbaceous perennial reaching 3-4 feet (90-120 cm) height, with glossy lance-shaped leaves.

Scientific Classification of Mexican petunia

Phylum

Vascular plants

Class

Dicotyledons

Order

Mints plantains olives and allies

Family

Acanthus

Genus

Wild petunias

Species

Mexican petunia

Planting and Growing of Mexican petunia

Care Difficulty

Easy

Watering Schedule

Every 8 days

Sunlight Requirements

Full sun

Sunshine Duration

4-6 hours

Ideal Temperature

70-85℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6.5-7.5

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Plastic, Ceramic

How to Water Mexican petunia?

When watering Ruellia simplex, aim to drench the soil thoroughly. Ensure water trickles out of the drainage holes, indicating the roots are accessible to the moisture they crave. This process usually requires around 200ml of water each session, considering typical pot sizes. Avoid allowing the pot to sit in excess water to prevent root rot.

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More About Watering Techniques→

What Are the Sunlight Requirements for Mexican petunia?

Sunlight Requirements: Full sun, Partial sun

Duration of light: 4-6 hours of sunlight

Ruellia simplex benefits from partial to full sun, meaning it can adapt to full-day exposure as well as moderated sunlight. The ideal light range supports its dynamic blooming cycle and ensures vibrant, healthy foliage.

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What Is the Ideal Temperature Range for Mexican petunia?

Ideal Temperature: 70 ~ 85℉

For Ruellia simplex, maintaining an ideal temperature range of 70°F to 85°F is crucial. This range supports optimal growth and ensures the plant remains healthy. Within this temperature range, Ruellia simplex can effectively photosynthesize and grow, leading to lush foliage and vibrant blooms.

What Soil is Best for Mexican petunia?

Soil type: Loam, Sandy loam

Soil PH: 6.5 ~ 7.5

Ruellia simplex thrives in well-draining soil as it prevents root rot and ensures healthy growth. This type of soil avoids waterlogging, which could otherwise lead to root diseases. Incorporating nutrient-rich compost is essential for vibrant growth. Compost not only provides necessary nutrients but also improves soil structure and moisture retention. Moderately fertile soil is beneficial as it supports the plant’s growth without risking nutrient overload. It strikes a balance, supplying nutrients essential for healthy foliage and blooms. More About Soil→

How to Fertilize Mexican petunia?

Fertilizer type: Balanced

For Ruellia simplex, a balanced all-purpose fertilizer with an N-P-K ratio of 10-10-10 should be used. Mix the liquid fertilizer at half the recommended strength to prevent over-fertilization. For slow-release fertilizers, use 1 to 1.5 lbs per 100 square feet. More About Fertilizing Techniques→

How to Prune Mexican petunia?

Pruning Time: Spring, Summer, Autumn

Start by locating any dead or woody stems. These can be pruned back to the base to encourage new growth and rejuvenate the plant. When trimming healthy growth, always cut above a leaf node. This encourages new branches to form below the cut, promoting fuller and bushier foliage. Ruellia simplex grows rapidly and can become unruly. Prune to shape the plant, ensuring a pleasing form and preventing it from overtaking neighboring plants. More About Pruning Techniques→

How to Propagate Mexican petunia plant?

Propagate Time: Spring, Early summer

Begin by soaking the seeds in water overnight to improve germination rates. This helps to break down any seed dormancy and allows water to penetrate the seed coat more effectively, enhancing the chances of successful sprouting.

Cut a 4-6 inch long piece from a non-flowering stem. Make a clean cut just below a leaf node, as this is where roots are most likely to develop. Remove the leaves from the bottom half of the cutting to reduce moisture loss.

For seeds, plant them in a well-draining soil mix and cover lightly with soil. For cuttings, dip the cut end in rooting hormone and insert it into a pot filled with a sterile rooting medium. Water the medium lightly and ensure it remains moist.

More About Propagating Techniques→

How to Repot Mexican petunia plant?

Repotting frequency: Every 1-2 years

Ruellia simplex requires repotting when its roots start growing out from the drainage holes or become root-bound. Additionally, if you notice a significant decrease in growth rate or water retention, it's time to consider a larger pot. The best season for repotting is during its active growth phase in Spring or Summer when the plant can quickly adapt to a new environment.

Select a pot that is just slightly larger than the current one; about 1-2 inches in diameter is ideal. Ensure the pot has ample drainage holes to prevent waterlogging, which can lead to root rot. A well-sized container helps maintain optimal moisture levels and gives roots adequate room to grow, promoting healthier and more vibrant foliage.

Opt for a well-draining potting mix that can retain moisture without becoming waterlogged. This typically includes components like perlite or sand mixed with standard potting soil. Such soil ensures that the roots receive adequate aeration and reduces the risk of fungal diseases, promoting a robust root system and overall plant health.