How to Grow and Care for Mexican Petunia

Mexican petunia, also known as Mexican bluebell, is not actually a petunia but is rather a highly adaptable, fast-growing perennial known for its petunia-like purple flowers. These versatile plants prefer full or partial sunlight, and they can handle many extreme conditions, including intense heat, high humidity, flooding, and drought.

Note that Mexican petunias are aggressive spreaders. Their underground rhizomes can 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.

Mexican Petunia Care

Here are the main care requirements for growing low-maintenance Mexican petunias.

• Plant in full sun for best blooms but partial shade may be fine for this flower.
• Use rich, well-draining soil to plant Mexican petunia.
• Keep the soil moist, but this is not a plant that needs monitoring for moisture.
• Fertilize lightly each spring if growing in a perennial zone.

Warning

Mexican petunias can quickly get out of hand due to spreading rhizomes and reseeding, and they will overtake native flora. According to the University of Florida, they are considered invasive in Florida.

Light

Mexican petunias are sun-loving flowers that prefer full sun conditions and will have purple stems when grown in full sun. These flowers also grow in part-shade, but will produce fewer flowers as a result, and will have green stems.

Soil

Mexican petunias are hardy, so they can typically survive in any type of soil. However, if you want these plants to thrive, grow them in a well-draining, rich soil.

Water

Mexican petunias do well in both dry and damp conditions, but they ideally should be kept evenly moist during the growing season and left to completely dry out before watering in winter.

Temperature and Humidity

These tough plants are heat and drought-tolerant. They thrive in areas with high humidity and high heat. 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.

Fertilizer

Fertilizer is unnecessary in most situations, however, you can fertilize these plants lightly with an all-purpose fertilizer if growing in a perennial zone.

Types of Mexican Petunia

• R. simplex ‘Chi Chi’ produces pretty, soft pink blooms and is highly tolerant of extreme heat, growing to two feet tall.
• R. simplex 'Mayan White' is sterile, produces white flowers, and grows up to 36 inches tall.
• R. simplex ’Katie’ is the most common Mexican petunia cultivar with purple blooms; a dwarf growing less than 1 foot tall.
• R. simplex 'Purple Showers’ is a winter-hardy sterile cultivar with all shades of purple blooms will not produce seeds but still spreads via rhizomes.

Propagating Mexican Petunia

Mexican petunias can be propagated through both stem cuttings and rhizome division; whichever method you choose should be done in summer.

Propagate by Cuttings

To propagate by cuttings, you will need sharp, clean garden snips, a small pot, well-draining and rich potting soil:

1. Take a pair of sharp garden shears and cut a 6-inch long stem right below a node.
2. If necessary, remove any leaves from the bottom half of the stem you have cut.
3. For best results, dip the cut end of the stem into rooting hormone, making sure to shake off any excess powder.
4. Plant the cutting in a small pot with rich, well-draining soil. The stem should be planted a few inches into the soil.
5. Place the pot in a warm area with bright light and keep it well watered so the soil remains moist.
6. Once the stem has formed a root system, transplant it into the garden.
   

Propagate by Division

To propagate through rhizome division:

1. Using a shovel, gently dig around the plant and loosen up the soil.
2. Slice through the rhizomes. This will create separate plants.
3. Take the plants you want to propagate out of the ground, and put them in their new location.

How to Grow Mexican Petunias From Seed

You can also grow Mexican petunias from seed:

1. Plant your petunia seeds in starter pots filled with moist, rich potting soil, being sure to cover the seed gently with the soil.
2. Put the pots in a warm area that receives bright, indirect light.
3. Check your seeds daily and keep the soil moist.
4. You should start to see the seedlings breaking through the soil in about 10 days.
5. Let the seedlings grow to a few inches tall, then begin hardening them off outdoors.
6. When the seedlings have been acclimated to the full sun, move them outdoors.

Potting and Repotting Mexican Petunias

Mexican petunias grow well in pots, which is especially useful if you live in a cold climate and want to overwinter them indoors. Mexican petunias do need to be repotted often, however, because they grow so quickly.

To repot your Mexican petunias, start by selecting a pot at least two inches larger than the current one. Dislodge the plant from its pot and set it into the new pot, then fill it with a well-draining, fertile soil. Be sure to bury the root system, then water thoroughly.

Overwintering

Mexican petunias don't need to be overwintered and do not need extra winter care when grown in warm climates with mild winters. You will just need to reduce watering, and only water when the soil is completely dry.

If you live in a cold climate, or are experiencing an unusual cold snap, move Mexican petunias indoors.

Common Pests

Mexican petunia plants are not afflicted with any serious pests or diseases. Tiny eriophyid mites, also called gall mites, can appear on plants and create dense and fuzzy white splotches on the leaves that look like furry paint splatters.

Simply pluck off the splotchy leaves on small infestations. Use horticultural oils to eliminate the mites.

However, to eradicate large infestations of this mite, cut the flowers down to a couple of inches above the ground. The mites can escape and damage other plants so be sure to discard the affected Mexican petunia plants by immediately putting them into a sealable plastic bag before disposing.

How to Get Mexican Petunias to Bloom

Healthy Mexican petunia plants should bloom readily, offering their signature purple flowers.

Bloom Months

Mexican petunias continue to prolifically produce their vibrant blooms for quite some time, usually from May to September. In warmer areas without frost, they can bloom all year.

What Does a Mexican Petunia Flower Look and Smell Like?

Mexican petunias are known for their petunia-like, purple, trumpet-shaped flowers that last about a day but produce new blooms daily. They do not have a strong aroma.

How to Encourage More Blooms

Place the Mexican petunia in an area that receives plenty of sunshine, as this will encourage abundant flowering.To encourage flower production, prune the plant after blooming.

Deadheading Mexican Petunias

Deadhead the spent Mexican petunia flowers to make room for future blooms.

Common Problems With Mexican Petunias

Mexican petunias can withstand droughts, floods, and high temperatures. Though hardy, there are some common issues you may experience, and one of the most common is brown leaves.

Aggressive Spreading

Mexican petunias' rhizomes spread vigorously, and their virile seeds also contribute to the plant's aggressive spread. Their seeds lack any sort of dormancy, with no requirement for scarification or cold stratification. This means that the seeds can germinate right away.

Plus, when the seeds get wet, they produce a gel coating that causes them to stick to things. They will stick to the ground, germinating soon after, and they'll also stick to animal passersby, who further distribute the seeds.

If you're concerned about this spread, consider planting sterile cultivars, such as 'Mayan White' or 'Mayan Purple.'

Brown Leaves

If your Mexican petunia has brown leaves, the most likely cause is damage from cold weather. 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.

From: thespruce