Mexican petunia (Ruellia brittoniana)

Mexican petunia can be invasive in wetland locations.

Mexican petunia (Ruellia brittoniana) is a perennial native to Mexico and cold hardy in the USDA planting zones 8 through 10. This plant grows to about 3 feet tall in full sun to part shade in moist locations. Because of its invasive nature in moist situation, plant Mexican petunia in areas where growth is restricted, such as in patio containers or plastic containers placed in garden ponds. Dwarf Mexican petunia may be a better, less invasive choice.

The trumpet-shaped blooms of Mexican petunia, which are about 2 inches across, appear in early summer. Blooms may be blue, white or pink.


Plant Mexican petunia indoors anytime of the year. Plant outdoors in the spring. Propagate by dividing the root ball. Another propagation option is to cut the stem into about 4-inch pieces. Dip the cut end into growth hormone. Make a hole about 1 inch deep in the soil and then insert the stem. Water around the stem to settle the soil. Keep moist.

If planting from a container, dig the hole the same size as the container. The soil at the top of the container-grown plant should match the surrounding soil level. Set multiple plants 1 to 2 feet apart.


After blooms fade, cut the stems back about halfway. The plant may bloom again the same season. Mulch, such as pine chips or leaf mold, spread to about 2 inches thick around the plant will help to block weed growth and retain moisture.

Image courtesy of Forest & Kim Starr

Perennials for water gardens: