Dwarf Mexican Petunias in the Winter

Identification

• Native to Mexico, as the name suggests, dwarf Mexican petunias are also referred to as Mexican blue bell, dwarf blue bell or dwarf water blue bell. This plant has long, lance-shaped green leaves on 3-foot stems, upon which the flowers sit. They bloom freely in June through September, and while not a part of the petunia family, dwarf Mexican petunias display blue to bluish-purple flowers that are shaped like petunia flowers and measure about 1 1/2 to 2 inches across. Varieties are also available with pink, white and lavender blooms.

Growing Outdoors in Winter

• While dwarf Mexican petunias tolerate high heat and humidity, they are less tolerant of winter conditions. They are hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10. They may withstand winters in zone 7 with protection, including mulch, but do better in warmer climates. When growing outdoors in winter, reduce their watering to a light soaking when the ground is truly dry.

Indoor Growth

• Although their natural hardiness range is pretty small, you can also grow dwarf Mexican petunias indoors. The species makes an excellent houseplant, generally free of pests and diseases. If you want to bring it indoors to overwinter and then plant it again in the spring, you can simply dig it up and pot it, then place in bright, indirect light. Again, moisten with water only when dry. It will grow well in containers year-round in houses and greenhouses.

Culture

• Dwarf Mexican petunia grows and flowers best when provided with lots of light. Although it can withstand a shady site, without ample sunlight, it produces far fewer blooms. The same holds true of cloudy or overcast weather, which will also reduce their flowering. Because the dwarf Mexican petunia is native to boggy areas -- it is technically considered a water plant -- moist conditions favor dwarf Mexican petunia’s best growth, but also foster invasive habits. Their aggressive nature makes it a bad idea to plant them too near wilderness zones, where they might escape and naturalize.