What Is a Zonal Geranium?

The zonal geranium, scientifically known as Pelargonium hortorum, is a type of flowering plant. It is known for its red or pink flowers, which may form in a cluster and bloom throughout the warmer months. The leaves of the plant are also visually striking. Although the zonal geranium is a perennial, it is usually grown as an annual in areas that receive freezing temperatures in winter, though some gardeners bring it indoors during the colder months. To survive, the plant needs plenty of sun.

Although the red-flowered zonal geranium is common, pink, white, or salmon-colored flowers are also available. The geranium will flower continuously as long as the weather stays above freezing. A gardener can encourage blooming by removing dead flowers before they go to seed.

The leaves of the zonal geranium come in a range of colors. Some leaves are banded with a bronze stripe or are white or silver striped. The green color of the leaves may be very dark or light. Typically, the leaves have three to five lobes on each stem. If bruised, the leaves may produce a faint scent.

The method of propagating the plant determines the type of flowers it produces. A plant grown from seed may have small flowers, while a plant rooted from a cutting will most likely produce the large clusters of flowers commonly associated with geranium. Seeds may be difficult to germinate at home and need to be started inside at least a few months before the last frost.

A gardener can root cuttings of zonal geranium by trimming a 4-inch (about 10-cm) long section of the plant from a branch. She should remove the leaves near the end of the cutting and place them in a pot with moist sand. After a short period of time, the cutting should form roots on the end, provided it received enough water to keep it from drying out. After the roots form, the cutting can be planted in the soil.

Zonal geraniums grow well in the ground or in containers. The plants require full sun to bloom. Adding too much fertilizer to the soil will inhibit flowering. At the most, fertilizer should be added when the geraniums are planted. The plants prefer soil that drains well and does not have too much clay. If planted in a container, the pot should have a hole in the bottom to allow for drainage.

Geraniums can also be grown indoors, in a spot that receives a lot of sun. A gardener can bring the plant in once the frost hits to keep it alive. Some people grow it as a houseplant while others dig the geranium up, shake the soil off of the roots, and store in a humid but cool location during the winter.