Glowing, green foliage and bright flower clusters over a long season make zonal geraniums (Pelargonium x hortorum) some of the most popular home garden annuals. Equally comfortable in garden beds, window boxes or porch and patio containers, these are easy-care, sun-loving plants. After months of outdoor bloom, some of them adapt to overwintering indoors. Zonal geraniums include plants grown from seed and cuttings.
Zonal cutting geraniums have a murky ancestry, said Auburn University Extension specialist and associate professor Dr. J. Raymond Kessler, Jr. They may be descendants of South African pelargoniums species collected for cultivation in the late 18th century. The commercial success of cutting zonal geraniums continued to rise into the 1980s.
Seed Geranium History
During the early 1970s, Pennsylvania State University introduced hybrid geraniums that would grow true--with new plants duplicating the characteristics of their parents--from seed. Seed zonal geraniums now command their own market popularity, said Dr. Kessler.
Zonal geraniums are mounding plants standing between 1 and 3 feet high. Seed plants are the smaller, more heavily branched variety. The flowers of both types occur in clusters on stems rising above their dense, rounded leaves. Foliage is solid green, or green marked with bands of differently colored pigment.
Seed geranium clusters have large numbers of single flowers. Zonal geraniums’ clusters have fewer, semi-double or double flowers. Flower colors for both varieties range from white to shades of pink, red, orange and purple. Some cultivars have bi-colored blooms.
Compact stature and regular habit make seed geraniums most appealing as mass garden bed plantings. More heat-tolerant than cutting zonal varieties, they're provide lots of reliable, late summer color, according to University of Vermont Extension professor Leonard P. Perry. Cutting zonal geraniums are early season performers and standout container plants.
Seed Geranium Propagation
Small, hard zonal geranium seeds germinate in 7 to 14 days if scratched before planting so water can enter them. Commercial growers plant them in flats or pots of sandy growing medium three months before the final spring frost date. They need consistently moist--not wet--soil. Seedlings perform best at 72 degrees F during the day and 65 degrees at night.
Cutting Zonal Geranium Propagation
Some zonal geranium cultivars require propagation from cuttings if the new plants are going to keep the characteristics of their parents. Three-to 4-inch cuttings taken from growing branch tips will root in well-watered, sandy medium and indirect light. Most zonal geraniums--seed or cutting--take between 95 and 110 days to flower, according to North Carolina State Cooperative Extension specialist Alice Russell.