It typically grows to 3-4' tall in the wild, but to 2-3' tall in gardens. Plants branch from the ground into several woody-based stems clothed with elongated, linear, willow-like, dark green leaves (to 6-12” long and ¾” wide) that are often tinged with purple.

Does Ruellia spread?

Ruellia is an aggressive grower, spreading both by seed and from its rhizomatous roots to a 3- by 3-foot mound, reports Plant Care Today. This plant is considered invasive in many areas, such as Florida, where it's a Category 1 invasive species.

How do you prune a Ruellia?

Mexican petunia, or Ruellia brittoniana, is easy to care for and takes all kinds of pruning, returning with a vengence even if pruned down to 6" above the ground. If that seems too drastic you can simply prune out the stems that have fallen over to make the plant look more attractive.