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2012- The Year of Geranium
by Sarah Browning, UNL Extension Educator
Each year the National Garden Bureau, http://www.ngb.org, selects a flower, perennial and vegetable to showcase, with plants being chosen for their popularity, variety, ease of growth, wide adaptability and versatility. This year the flower being featured is the much-loved, and very versatile geranium, botanically known as Pelargonium spp. In this instance, we're talking about beautiful, showy annual bedding plants, not the hardy perennial geraniums, although both Pelargonium and Geranium are in the same family.
Since their discovery in South Africa and introduction to England in the 17th century, gardeners' enthusiasm for geraniums has never waned and breeding efforts have been ongoing since that time. At least 249 species of Pelargonium are known, all native to South Africa.
There are four types of geraniums with which most gardeners are familiar. The most common is the zonal geranium, known as Pelargonium x hortorum, followed by ivy geranium, P. peltatum, regal geranium, P. x domesticum, which is also sometimes known as the Martha Washington geranium, and the scented geraniums that comprise about six different species. Regal and scented geraniums are best used indoors as gift plants, while P. x hortorum and ivy geraniums do great outside in landscape plantings or containers. Zonal geraniums get their common name from a semi-circular area of darker leaf coloration, running across the middle of the leaf, although it is more evident in some cultivars than in others.
Geraniums can easily be propagated through stem cuttings, but since geraniums are susceptible to viruses and bacterial diseases that can be spread through cuttings, there was a need for cultivars that could be successfully seed propagated. Today plants may originate either from cuttings or seeds, however, with geraniums propagation method does have an effect on flower development. Specifically, seed propagated plants usually have a single layer of petals on each individual flower, while vegetatively propagated plants often have semi-double flowers. But since a geranium flowerhead is made up of many individual flowers, gardeners may not have noticed this difference.
Geranium species can now be easily crossed and the crossing of ivy and zonal geraniums created a new geranium class, the interspecific hybrids, resulting in some great cultivars for landscape use.
Two interspecific geranium hybrids with good attributes for the landscape are the Calliope and Caliente series, each encompassing several colors. Plants in both series have strong branching, good heat tolerance and excellent disease resistance. Plants in the Calliope series most closely resemble zonal geraniums in leaf structure and form, while those in the Caliente series look and grow more like ivy geraniums. Look for plants sold under the Proven Winners brand in many local nurseries and garden centers.
However, so many great geranium cultivars are available in the nursery industry now that it's hard to go wrong, if you find a flower color you love!
Zonal and ivy geraniums grow best in full sun or, at a minimum, 4-6 hours of direct sun each day. Choose a location with well-drained soil, and incorporate 3-4 inches of organic matter into heavy or sandy soil before planting for best growth. Provide plants with good moisture throughout the summer and remove spent flower heads weekly to keep plants looking neat and blooming continuously. Geraniums are heavy feeders, so incorporate a granular fertilizer into the soil before planting, and apply a balanced, water soluble fertilizer (10-10-10) monthly throughout the summer.
For more information on this year's featured plants, visit the National Garden Bureau at http://www.ngb.org.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
Contact Information University of Nebraska-Lincoln in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528 | 402-441-7180