A dwarf form of Mexican petunia that stays low, with narrow dark green leaves and purple-blue trumpet flowers from spring through fall. It is far better behaved than the tall species and works as edging or a small-space filler in sun or part shade.
Living with it in the Phoenix Valley
Watering
Follow the shrub schedule in our Landscape Care guide. It tolerates short dry spells once established, but looks fullest with steady moisture in amended, well-drained soil. Avoid soggy ground, which can lead to root rot.
Pruning
Cut it back in late winter, after the danger of frost, to clear damaged leaves and push fresh growth. Shear lightly during the season if it gets rangy.
Spread
Unlike the tall Mexican petunia, Katie stays compact and is not considered invasive. It can still self-seed a little into nearby beds; pull stray seedlings when you see them.
How our designers use it
Edging
Its low, even height makes a neat border along walks and in front of taller shrubs.
Part-shade beds
It handles part shade beneath small trees and on the east side of the house, where many desert bloomers thin out.
Good to know
Around the pool
No thorns, and it stays low and tidy beside pool decks and walks.
Invasive relatives
The tall, purple-flowered Mexican petunia (Ruellia brittoniana, also sold as R. simplex) can spread aggressively and is invasive in some warm, wet regions. Katie is a compact selection that is far less aggressive, so make sure that is what gets planted.
