Mexican petunias can bring beauty to your garden if you take care to select cultivars that are not invasive and that you can keep up with and manage.
blue-purple petunias? Mexican petunias may initially be mistaken for regular garden flowers.
Ruelliasimplex, a fast-growing perennial with green to purple stems and green leaves, are what Mexican petunias are in reality. This plant’s invasive, wild version is so aggressive that some states have prohibited it, while others have put it on a watch list of invasive plants. Mexican petunias are categorized as “extremely invasive” by the state of Florida.
Ruellia simplex, also known as R. tweediana, R. brittoniana, R. coerulea, and R. malacosperma, is a plant native to Mexico and western South America that can withstand freezing temperatures in USDA hardiness zones 8 to 11. Even though the plants were given their correct name by a German botanist in 1879, most horticulturists today call them R. tweediana. Mexican bluebell, hardy petunia, wild petunia, Britton’s wild petunia, and perennial petunia are examples of common names.
Mexican petunias may thrive in a variety of environments but prefer moist or marshy soils, such as those found at the edges of ponds and lakes or in moist woods. In dry soils, they can endure drought and even full sun.
The plants’ colorful, spectacular blossoms are fleeting, yet they bloom for a long time, starting in early spring and lasting until frost. The shrubs have an approximate width of one foot and a height of one to four feet.
Most of these lovely, hardy plants have the unfortunate drawback of spreading out of control and displacing good plants.
Invasive Mexican petunias develop thick, horizontal roots that extend above and below the surface of the earth, making them challenging to uproot. Even small portions that are missed can reseed. When ripe, seed capsules on the plants open and release seeds all over the place. Years after the plants have been eliminated, the seeds may still be present in the soil and begin to grow.
Even worse, when the seeds are moist, a mucous-like goo forms. They adhere like glue to dry soil once they are dropped there.
Mexican petunia varieties that gardeners can enjoy and cultivate responsibly have been developed by breeders. Because they are sterile cultivars, “Mayan Purple” and “Mayan White” do not produce seeds that self-sow.
‘Mayan White’
Mexican petunias are invasive, however “Mayan White” and its relative “Mayan Purple” are sterile substitutes.
Home Depot locations in Florida presently carry “Mayan Purple” and “Mayan White.” By 2014, the breeder, Rosanna Freyre, hopes to have the cultivars more widely accessible. This may involve cooperating with a North Carolina mail order business and a Georgia company with statewide distribution.
Another possibility is “Katie.” Due to its lovely blossoms and simplicity of maintenance, Texas A&M University has named this less aggressive, dwarf Ruellia a Texas Superstar.
‘Katie’ has blooms that are purple, pink, or white and grows to a height of about 6 inches. However, because it is fertile and spreads through seed, researchers from the University of Florida and the Institute of Food and Agricultural Services do not advise using it.
How quickly does the Mexican petunia grow?
Mexican petunia, also known as desert petunia, quickly takes root when you start with a seedling or young plant that has been produced in a nursery. Typically, clusters of 3 foot tall, sturdy, semi-woody stalks bearing lovely leaves and blooming within a month or two are produced. The plant’s first season typically features purple flowers that bloom from mid-spring until late-fall. Placing the plant in full light will encourage quick, healthy growth and an abundance of blossoms. This will also encourage the development of flower buds and keep the leaves a deep, rich green.
Are Mexican petunias contagious?
Mexican petunia, often known as ruellia, may add color and height to your summer borders. This low-maintenance plant grows to a height of 3 feet (although there are dwarf types that stay shorter) and produces waves of petunia-like blue, white, or pink flowers throughout the summer. The colorful insects swarm to the fragrant petals of Mexican petunia, making it a perfect choice for butterfly gardens. Additionally, Mexican petunia is a necessary plant for butterfly gardens because various species of butterflies need it as a host plant for their larvae to feed on. Mexican petunia will frequently self-sow after it is established and spread widely in the garden, so plant it in areas where you can monitor it or in sizable container gardens. Deer can’t eat Mexican petunia. Hardy in zones 9 through 11.
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Mexican Petunia Growing Instructions
It thrives and blooms best in broad sun or light shade for Mexican petunia. Although it can grow in the shade, it won’t blossom as much and will appear lanky and leggy. Mulch the plants to maintain regular soil conditions, especially in hot, dry weather, as this sun-loving perennial prefers rich, somewhat damp soil. Mexican petunias can be grown as annual flowers in the northern hemisphere. Mexican petunia may spread quickly, so plant it in an area where you can limit it.
Restrictions may apply to some of these plant’s varieties since they are thought to be invasive. Before planting, check the local laws. At Costa Farms, only non-invasive hybrids are grown.
Include these types with your Mexican petunias:
Mexican petunia height limit
Characteristics of the Species Mexican-petunia is a perennial that grows up to 3 feet tall in zones 8 to 11. Dark green, oppositely arranged, lance-shaped, stems that are green or purple, with leaves that are from 6 to 12 inches long and 1/2 to 3/4 inches wide.
Are Mexican petunias sun or shade lovers?
Light. Mexican petunias enjoy the sun and do well in direct sunlight. They also do pretty well in regions that are somewhat shaded, however blossom production is decreased by the shadow. While plants cultivated in the shade will have green stems, those planted in full light will have purple stems.
Do Mexican petunias appeal to hummingbirds?
Our friend gave us some unidentified seeds about three years ago. They came from a “dark green plant with blue blossoms that resembled crepe paper. They were positioned by our garage in a garden nook. We quickly developed a dark green shrub with serrated leaves that eventually produced beautiful blue tubular blooms. It refroze during the winter and then reemerged in the spring. AND it spread, but we discovered that the tiny self-seeded plants were simple to remove.
Without success, I tried to identify this plant. I thoroughly read the Sunset Western Garden Book, consulted other gardeners who visited our garden, and, in the end, gave up the search. Then, last week, when on a trip with the Vaca Valley Garden Club at High Hand Nursery in Loomis, I came across our plant. It is a Mexican petunia, or Ruellia brittoncana. The mysterious plant was finally identified and given a name.
Research revealed that this plant is native to Mexico and is simple to grow in either dry or moist soil. They are evergreen shrubs that reach heights of 3 feet and a width of 4 feet. There are a few dwarf kinds available, like “Katie,” which reaches a height of 10 inches. These plants produce flowers in a variety of blue, purple, or white hues with little care. The two plants are not related, despite the fact that they resemble the petunia bloom we are all familiar with. Because the plants’ vibrant blossoms draw butterflies and hummingbirds, many home gardeners grow them.
Due to its invasiveness, Ruellia is either adored or despised by gardeners. There is a sterile variety with deep purple flowers named “Purple Showers” that will not self-seed. Even though it won’t reseed, if cultivated in wet soil, it can spread by its roots. They are also known as desert petunias and grow more flowers the more sun they get. Mexican petunias can be propagated through division, seeds, or cuttings.
Once established, plants planted in the early spring will bloom all through the summer and into the fall. Although young plants require routine watering, the plant is sturdy enough to endure prolonged periods of dryness. They adapt quickly and thrive in containers as long as they get sunlight. The best news is that Ruellia brittoncana is very resilient to the majority of illnesses and pests.
How are Mexican petunias kept in check?
A yard or garden bed can be swiftly overrun by Mexican petunias. Several measures can be taken to prevent Mexican petunias from encroaching in other places.
To slow down and restrict the spread of the plant, bury wood planks approximately six inches thick around it.
A larger Mexican petunia should be planted in a pot and placed in an established garden. Before the plant needs to be repotted, the roots will expand within the pot and let it to blossom wonderfully for years.
The plant will be forced to develop as a ground cover without encroaching on other parts of the garden if it is placed in a walled area far from other plants.
Mexican petunia seeds can disperse, so if you find a sprout in a spot where you don’t want the plant to grow, pull it out as soon as you can to prevent it from setting roots and creating a problem.
Do you need to reduce your Mexican petunias?
Typically, a Mexican petunia only needs one annual pruning in late winter or early spring to remove any damaged, weak, or unwelcome stems back to the plant’s root system. During the flowering season, trimming spent flower stalks helps keep the garden looking tidy. Every few years, in the spring, trim Mexican petunia clumps back to a few inches above the ground to revitalize them.
The spread of this plant can be controlled with specific pruning methods. Cut off any spent Mexican petunia blooms before they set seed and pluck away any stems that have fallen to the ground and become rooted in the soil.
Poor lighting
The first thing to do when you see petunias are lacking blossoms is to determine how much light they are receiving. If there are petunia plants without flowers, check to see if they are receiving direct sunlight at different times of the day. Petunias require full sun for the best possible bloom display. Although a petunia may not bloom if it receives less than six hours of direct sunlight each day, it may do so when it receives mild shade for a portion of the day.
Petunia plants in containers that aren’t blooming should be moved to a sunny spot. By pruning or cutting nearby plants that may be shading them, non-blooming petunias that are planted in the ground might receive more sunlight. You might need to replant the petunia plant with no flowers if you planted it in a shaded area that can’t be improved.
Wrong fertilizer
Petunias could not be receiving enough water or fertilizer if the lighting is ideal and they aren’t blooming. Although petunias may tolerate some drought, moist soil will result in a more luxuriant show. Petunias that were planted in the ground should have any excess water shaken off since moist buds can decay before blossoming.
Try this solution if you haven’t been feeding your petunia plant if it hasn’t been producing flowers. Liquid fertilizer is frequently applied to a lot of nursery-grown plants, but it only stays in the soil for a short time before being washed out by watering. The reason the petunias have lush foliage but no blooms may be that they were treated with a high nitrogen plant food.
Switch to phosphorus-rich fertilizers, like ones marked “bloom buster.” Another excellent source of phosphorus is bone meal. The middle value in the three-digit fertilizer ratio mentioned on the box is phosphorus. Pick a product with the label 10/30/10. If you want your petunias to put on one last show before the summer is out, a balanced fertilizer might work.