Seed Geraniums Vs. Zonal Geraniums

Widely grown zonal, or common, geraniums (Pelargonium x hororum) were traditionally propagated by rooting cuttings. Plant breeders eventually developed F-1 hybrid zonal geraniums that can be grown from seeds. There are differences in size, branching and flowering habits between traditional zonal cultivars and zonal cultivars that can be grown from seed.

Both traditional zonal geraniums and seed cultivars are tender perennials; they can be grown as perennials in U.S. Department of Agriculture plant hardiness zones 9 and 10 but are grown as annuals elsewhere. Grown as perennials, they go dormant before the first autumn frost and begin growing again in spring. Grown as annuals, they die with the first autumn frost. Potted geraniums can easily be taken inside to survive the winter.

Seeds bloom from 95 to 110 days after germination, usually in late spring to early summer and continuing to the first autumn frost. Cuttings from traditional zonal geraniums develop roots in two to three weeks.

Traditional zonal geraniums grow clusters of 4- to 5-inch-wide flowers in numerous colors including but not limited to lavender, magenta, violet, pink, orange, salmon crimson, red and white. Flowers of seed cultivars are typically smaller.

Neither traditional nor seed zonal geraniums are considered poisonous, although eating any plant can cause an allergic reaction to sensitive humans or animals. Confusion on this issue may exist because handling the leaves of ivy geranium (Pelargonium peltatum, USDA zones 10 and 11) may cause skin irritation.

What we commonly call zonal geraniums, originally members of the Geranium genus, were later reclassified to the Pelargonium genus. They were traditionally propagated by cuttings, but with the passing of years, they were frequently hit by disease and their vigor declined.

In 1962, a botanist at Penn State University nicked Pelargonium seeds, a technique called seed scarification, to successfully grow Perlagonium x hororum "Nittany Lion Red" from seed. The zonal geranium that previously had to be grown from cuttings could now be grown from seeds.

In the years that followed, plant breeders introduced more zonal geraniums that could be grown from seed, called F-1 seed hybrids. In 1991, plant breeders introduced F-1 seed hybrids with stouter stems and larger flowers. F-1 seed hybrids with colored leaves were introduced after 2000.

When somebody says "geranium," she typically means zonal geraniums that have colorful leaves and are easy-to-maintain plants. They are called zonal geraniums because they have a stripe down the center of their leaves.

Some traditional zonal geranium species are dwarfs less than 10 inches tall; some are miniatures less than 6 inches tall. There are species with star-shaped leaves and flowers, and species that yield profuse amounts of flowers.

Examples of zonal geraniums that must be propagated by cuttings include:

"Bravo" (Pelargonium x hortorum "Bravo") has dark green leaves and dark pink flowers.

"Hollywood star" (Pelargonium x hortorum "Hollywood Star") has star-shaped flowers in rose and white.

"PAC Evening Glow" (Pelargonium x hortorum "PAC Evening Glow") yields dark salmon flowers and grows well in summer heat.

F-1 hybrid seed geraniums are typically smaller plants than zonal geraniums that must be propagated by cutting. They grow more branches and more flowers, making them good choices for traditional flower beds. They also grow faster than cultivars that are propagated from cuttings.

Traditional zonal geraniums yield flowers with double rows of petals. The smaller flowers of F-1 hybrid seed cultivars usually have single rows of petals. More than 150 F-1 hybrid seed varieties of zonal geraniums are now on the market, including:

Some F-1 hybrid zonal geraniums include:

"Solo," also called "Bronco" (Pelargonium x hortorum "Solo"), is a seeded version of the traditional red geranium.

"Picasso" (Pelargonium x hortorum "Picasso") yields violet flowers.

"Geronimo" (Pelargonium x hororum "Geronimo") grows deep scarlet flowers.

"Pinto" (Pelargonium x hortorum "Pinto") is a series of dwarf geraniums that grow from 10 to 14 inches tall, coming in 10 different colors.