Actual size and flowering may vary slightly based on season.
Purple Ruellia
Purple Ruellia, also called Mexican petunia, fills beds with violet-purple, petunia-like flowers from spring until frost. It grows fast into an upright clump about 2 to 4 feet tall, with long, narrow dark green leaves. It does well in full sun or part shade and looks lush near pools and water features. Bees, butterflies and hummingbirds come to the flowers.
Best for: lush beds near pools and water features, bordered flower beds, containers, and fast color in sun or part shade.
It suits beds near pools, ponds and water features, where its long leaves and steady flowers give a lush look. Plant it 18 to 24 inches apart, and it fills in fast.
It fills a bed fast and flowers from spring until frost in sun or part shade. More sun means more flowers and a bushier plant.
A large pot keeps its fast growth in check and puts violet flowers on the patio all summer. Water the pot regularly in summer to keep it blooming.
It spreads by seed and underground runners and can take over wet or flood-irrigated yards, so keep it in a bordered bed. Frost blackens the tops, and it looks rough until you cut it back.
- Bed or border18-24 in apart, center to center
- Mass planting18 in apart, center to center
Water every few days at first, then stretch the time between soaks over the first two months. Water deeply and let the top of the soil dry before the next soak.
It flowers best with regular water in summer and less in winter. Use drip rather than flood watering, which makes it spread fast.
Frost blackens the tops, often in the mid 20s, but the roots survive. Cut it back hard in late winter, and it regrows in spring.
It spreads by seed and underground runners, most where soil stays wet. A bordered bed or a pot keeps it in check.
Drainage test first. Dig the hole and fill it with water. If water is still sitting in the hole a day later, you likely hit caliche, clay or hard soil, so fix the drainage before planting. If it drains very fast, the soil is sandy. Standing water around roots is a common reason new plants fail.
Weed cloth. Cut it away from the planting hole and where the roots will spread. Remove any plastic sheeting completely, since it keeps water and air out of the soil.
Rock or decomposed granite with no soil underneath. Bring in soil close in texture to your native soil, mix it with the soil below, and build up enough depth for roots before planting.
If you can break through. Use a breaker bar, pick, or jackhammer. Dig through the caliche and break out the solid chunks. Backfill with the soil you dug out, with no compost or manure in the hole. Confirm drainage before planting.
If you cannot break through. Dig narrow holes through the hard layer beside the root ball, not under it, and refill them with the same soil, not gravel. If it still will not drain, plant on a low mound of the same soil.
Root ball. Check the outside edges for any roots circling around. Loosen or cut those so they grow outward. Do not break up the center of the root ball.
Depth. The top of the root ball should sit at or just slightly above the surrounding soil level. Planting too deep can lead to rot and kill the plant.
Drip emitters. At planting, put the emitters on the root ball, on different sides of the plant. After about 2 months, move them to the outer edge of the root ball. Over the first year, add emitters farther out toward the edge of the branches as roots grow. Once a plant is rooted, never water only at the trunk.
How big does purple ruellia get?
It usually grows about 2 to 4 feet tall in upright clumps about 2 to 3 feet wide. It grows fast, and the clumps widen over time.
How far apart should I plant it?
Plant it about 18 to 24 inches apart, center to center. Use 18 inches for a mass planting that fills in quickly.
When does it bloom?
It blooms from spring until frost, and in a warm winter it can keep flowering. Each flower lasts about a day, but new ones keep coming as long as you water regularly in summer.
How often should I water purple ruellia?
It takes some drought once rooted, but it flowers best with regular water in summer and less in winter. Use drip rather than flood watering, since wet soil makes it spread fast.
Does it need sun or shade?
It grows in full sun to part shade. More sun gives more flowers and a bushier plant, while too much shade means fewer flowers and floppy growth.
What happens when it freezes?
Frost turns the tops black, often in the mid 20s. The roots survive, and it regrows in spring.
When should I cut it back?
Cut it back in late winter, after frost damage. Cut it down to a few inches, and new growth comes up quickly.
Is purple ruellia invasive?
It spreads by seed and underground runners and can take over a yard that stays wet or is flood irrigated. It is listed as invasive in Florida and has spread into wild areas in other warm, wet states.
How do I keep it from spreading?
Plant it in a bordered bed or a large pot, and avoid keeping the soil soggy. The seed pods pop and throw seed, so pull seedlings that come up where you do not want them.
How is purple ruellia different from Katie dwarf ruellia and desert ruellia?
Katie is a dwarf form about a foot tall that spreads far less. Desert ruellia is a different, woody shrub with small leaves that does not spread. Purple ruellia is the tall, fast, spreading one, so choose Katie or desert ruellia if you do not want a spreader.
Does it attract hummingbirds and bees?
Yes. Bees, butterflies and hummingbirds visit the flowers. Plant it in full sun for the most flowers.
Purple Ruellia for sale in Arizona, delivered to you
Purple Ruellia (Ruellia simplex, long sold as Ruellia brittoniana) is the tall Mexican petunia, with violet-purple flowers and long, narrow leaves. It grows fast to about 2 to 4 feet. Below you will find its size, spacing, bloom, water, sun, frost and cutback, how it spreads, and how it compares with Katie dwarf ruellia and desert ruellia.
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What is Purple Ruellia (Mexican petunia)?
Purple Ruellia is the tall Mexican petunia, with violet-purple flowers and long, narrow dark green leaves. It grows fast to about 2 to 4 feet and blooms from spring until frost. It is also sold as Ruellia brittoniana.
How far apart do you plant purple ruellia?
Plant it about 18 to 24 inches apart, center to center. It grows fast and fills in quickly.
How often do you water purple ruellia in Phoenix?
It handles some drought once rooted, but regular summer water keeps it flowering. Avoid keeping the soil soggy, since wet soil helps it spread.
Does purple ruellia come back after a freeze?
Yes. Frost blackens the tops, but the roots survive. Cut it back to a few inches in late winter and it regrows in spring.
Is Mexican petunia invasive?
It spreads by seed and underground runners and is listed as invasive in Florida. In yards it can take over wet or flood-irrigated ground. A bordered bed or pot keeps it in check.
What is the difference between purple ruellia and Katie dwarf ruellia?
Katie is a dwarf form of the same plant, about a foot tall, and it spreads far less. Purple ruellia is the tall form at 2 to 4 feet.
Does purple ruellia grow in sun or part shade?
It grows in full sun to part shade. More sun means more flowers and a bushier plant, while deep shade makes it floppy.
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