A double geranium is a geranium that grows at least ten petals, resulting in a larger, showier flower head. The flower clusters can measure up to 5 inches (12.7 cm) in diameter and the double geranium comes in many colors and types. The flower is a type of Pelargium called zonal geraniums whose flowers may be single, semi-double, or double. Newer varieties of ivy geraniums can also feature semi-double or double blooms.
The geranium family is made up of different genera of plants, all of which are commonly referred to as geraniums. Only one genus is actually Geranium and plants which belong to this genus are usually called "hardy geraniums." The type of flower most often thought of as geraniums actually belong to the genus Pelargonium which originated primarily from the Southern African region. This type of geranium usually features scented foliage and leaves. Their flowers are naturally five-petaled but many variations, of which the double geranium is one, have been produced over time.
The first double geranium was the result of work done by Victory Lemoine, a gardener and avid breeder of plants, born in France in 1823. The Gloire de Nancy was the name he gave to the first double geranium he produced in 1860 and is the plant from which all common geraniums grown today descend. By 1869, he listed 70 double flowered zonal geraniums. Double geraniums come in a wide range of colors such as reds, pinks, white and purple.
Classical garden geraniums, belonging to the Pelargonium genus, are plants with large clusters of flowers carried on long stalks. Some subcategories of zonal geraniums are those which resemble carnations, cactus flowered and fancy or variegated leaf geraniums. Scented geraniums also belong to the Pelargonium genus and the scent carried by the leaves include lemon, mint, strawberry and peach.
Caring for geraniums is quite a simple task and is one of the reasons they are so popular. They can be grown outdoors all year long in mild, frost-free climates and thrive in a variety of soils. The biggest threat to growing geraniums is frost and should tops become weather-damaged, then they should be trimmed back. As for propagating Pelargonium, cuttings may be taken in late summer or winter and then laid out to dry for a day or two. This will prevent them from rotting once they are inserted in moist soil.
Double geraniums are generally drought tolerant and pest resistant. They grow to a height of 24 to 36 inches (60 to 90 cm). They can flower for up to six months a year which makes them a colorful addition to any garden. They generally require regular dead-heading, where the dead flowers are pinched off, in order to encourage new flowers.