Mexican Petunia ( Ruellia Brittoniana) Info and Care
Despite its name, the Mexican petunia is not a petunia nor its relative but a perennial in the genus Ruellia of the Acanthaceae family.
What connects this plant with petunias, the most popular seasonal and balcony flowers from the Solanaceae family is the similar shape of the flower which is why this plant with the Latin name Ruellia Brittoniana ( previously R.Simplex) is commonly named Mexican petunia.
Other common names include synonyms like Hardy petunia, Mexican bluebell, and Britton’s petunia.
What is Mexican Petunia
As its name suggests, ruellia is native to Mexico and the southern parts of the USA, but you can also see the plant as a native species in the Caribbean or South America.
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The Indigenous plant is a fast-growing perennial that forms an upright shrub reaching between 3 to 6 feet high and the same width,
However, thanks to cultivation, today you can get much smaller and even dwarf varieties that do not grow more than 12 inches.
Its leaves are oleander-like, pointed, elongated, sometimes 6 inches long, dark green, and intertwined with purple veins. They grow opposite on firm, upright purple stems with pronounced nodes. The combination of dark green and purple makes the plant attractive and striking even outside the flowering season.
Yet its main attraction is the 2-inch diameter lilac-blue, pink, or white tubular flowers composed of five paper-like, delicate petals.
Each flower, unfortunately, lasts only one day, but this multi-stemmed plant gives numerous new flowers every day, so the flower show continues from late spring to late autumn.
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How to Care for Mexican Petunia
Mexican petunia is an adaptable, undemanding, and resilient plant capable of surviving in various conditions. Once planted, the natural beauty usually does not need additional care or nutrition. Yet, here is the elementary surrounding you have to provide for its cultivation:
In climate zone 8 and above, the Mexican petunia grows as a garden plant that overwinters in the ground. Since it rejects the leaves when the temperature drops below 32 F, you could cut the stems back and put a layer of mulch to prevent root freezing.
The root can withstand temperatures up to 18 F without damage, so, as soon as it warms up, new shoots appear, and the Mexican petunia continues to grow.
In climate zone 7 and below, you can grow Mexican petunia as an annual or perennial in a large pot that spends the winter in a frost-free area.
Although often referred to as a shade-tolerant plant, the Mexican petunia grows faster, forms a more compact shrub, and blooms more abundantly if grown in full sun. Only in a hot Texas summer, the plant feels better in a shaded place.
In addition, its stems in the shade remain green, so the plant is not as attractive as the one that grows in full sun.
The Mexican petunia is not particularly picky about the soil as long as the soil is well-drained and sufficiently nutritious. It can grow in loamy or sandy, slightly acidic, or neutral ground. Therefore, you should loosen compacted garden soil before planting and add manure and sand to increase permeability and nutrients.
If you want to grow it in a pot, prepare a mixture of equal parts of ordinary garden soil, sand, and compost.
The Mexican petunia likes evenly moist but not soaked soil. The branched rhizome root reaches deeper soil layers with more moisture and deposits water supplies. Therefore the plant can withstand drought conditions but grows more vigorously if given plenty of moisture.
Therefore, when it comes to watering, except in arid areas, you can rely on natural precipitation.
Naturally, it would be best to water the potted plants more often, usually when the soil surface dries to two inches.
Invasiveness and Propagation
Mexican petunia is easily propagated by seed, root division, or semi-mature cuttings rooted in a glass of water or wet soil. Multiple possibilities of propagation might sound great but still has their drawbacks.
From pollinated flowers, the plant develops a 1inch long seed capsule, and each, when opened, spills a dozen disk-like seeds on the ground. If the soil is moist, many new plants can sprout all around, sometimes even at a distance of 10 feet from the parent plant.
In addition, the plant gives new shoots from the rhizome root, constantly expanding.
All this put the Mexican petunia on the list of invasive plants in Florida, and once you plant it, don’t be surprised if it spreads all over the yard or escapes into your neighbor’s garden!
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