Petunias are a common sight in almost any garden or landscape and with good reason: They are easy to maintain, come in a wide variety of colors and sizes, and can be bought just about anywhere. Their popularity, however, should not encourage you to take them for granted.
Petunia cultivars tend to fall under two main types, the larger-flowered grandifloras and the smaller multifloras. The largest flowers can be up to 7 inches; the smallest, around 2 inches. Single-flower varieties generally produce bell-shaped flowers. The double-flowered varieties resemble carnations, with densely clustered petals forming fluffy balls. Colors include a range of pastels, plus deep red, blue, white, and several shades of yellow, and they can be solid, striped, or splotched with white. The petal edges may be wavy, ruffled, or fringed. Petunias provide constant color between the different blooming periods of perennials. They can also be used effectively in window boxes, patio containers, or hanging baskets, and there are several cascading varieties that work well in these locations. Though usually considered annuals, petunias are actually delicate perennials and may survive year-round in mild locations.
All petunias thrive in full sunlight. Shade tends to discourage flowering and will also cause the plants to become leggy as they reach for more light. Even in full sun petunias can become spindly. The best way to control this is to pinch back the tips when the plants are still young to encourage bushier growth. Additional pinching and removal of spent flowers should be done throughout the growing season.
The single-flowered varieties are more tolerant of poor soil — their main requirement is good drainage. All varieties are drought-resistant despite their delicate appearance. Of course, they will appreciate watering during a dry period—just be sure to spray manually underneath the flowers, lest they become water spotted. After a summer storm petunia flowers will look fairly ragged, but removing the most damaged flowers encourages a hasty rejuvenation. Fertilize petunias about once a month.
In the evening your petunias will bring additional life to your landscape, for they attract beautiful moths, and the brilliant white-flowered varieties appear to glow in the moonlight.