A zonal pelargonium is a group of geranium hybrids commonly called zonal geraniums or common geraniums. These plants are a hybrid cross between pelargonium and hortorum. The zonal geranium gets its name from the leaves that are divided into "zones" with dark bands of color. The zonal pelargonium is a frost-tender perennial that is commonly grown as an annual. The large flowers come in a variety of vibrant colors and mixed colors.
The plants are commonly grown in the landscape as bedding plants or in patio planters. They also grow well in hanging baskets and indoor pots. They grow 1 to 3 feet (about 30 to 90 cm) tall with an upright growth pattern. The flowers are complex with tightly curled petals that create a large puffy looking flower. Zonal pelargoniums come in salmon, red, white, pink, orange and violet. Within each color there are numerous shades.
In mild climates, zonal pelargoniums can be grown year round. As long as temperatures rarely drop below 30°F (about -1°C), the plants will survive. In most areas where temperatures regularly drop below freezing in winter, zonal geraniums can be grown as annuals and replanted each spring from starts.
Zonal pelargoniums can be planted in pots sunk into the ground. In fall, the pots are dug up and put indoors or in a protected greenhouse for the winter. This provides the beauty of garden planted flowers that are also easy to bring in for the winter. An alternative is to dig up and transplant the plants into pots for the winter.
These plants grow best in a spot in full sun or part shade. They require loamy soil with good drainage. At planting time, zonal pelargoniums must be positioned so that the bases of the stems are level with the surrounding soil line. If planted too deep, the roots and stems can rot and kill the plant. After planting, zonal pelargoniums should be fertilized once a month using a balanced flower food fertilizer.
In planters and patio pots, zonal pelargonium plants create vibrant color in indoor and outdoor living spaces. They require a well-draining potting soil and a planter with holes in the bottom for drainage. The pots should be kept slightly damp but not saturated. Yellowing and dead leaves around the base of the plant are an indicator that the zonal pelargonium is under watered. When the soil is wet and muddy, the plant is too wet and is likely to rot.
Potted zonal pelargonium plants can be kept outdoors between spring after the last frost date and fall. The pots must be brought in before the first frosts. Indoors, zonal pelargoniums grow best in a sunny window or a heated porch or greenhouse.