Institute of Food and Agricultural Sciences
Hendry County Horticulture News
Geraniums - A Popular Favorite
Almost every garden shop and retail outlet offers a wide range of geraniums for sale indicating their wide appeal and popularity among gardeners. One of the many nice characteristics about geraniums is that they grow so well and look so good in number of situations. The colors are spectacular and include a wide range: bright red, scarlet, scarlet-and-white, orange-salmon, coral, pink and white, soft pink, hot pink, pure white, and lavender. From dwarf to compact to tall plants; single, semi-double, and double florets; increased disease resistance; early bloom and even fragrance - the possibilities are incredible. They combine well with a number of other plants: lobelia, vinca, parsley, petunias, verbena, dusty miller, and ageratum, to name a few.
The familiar geranium that gardeners buy in abundance at garden centers is Pelargonium. Mistakenly called geraniums, it wasn't until the end of the 18th century that pelargoniums were placed in their own genus. But the common name has remained, at least in North America. In south Florida, geraniums are treated as annuals because of the difficulty of carrying the plants through the hot season.
The first plants were brought from South Africa to England by famed plantsman John Tradescant in the early 17th century. African pelargoniums quickly became popular conservatory plants, although rare enough that only the well-to-do could afford them. By the beginning of the 18th century, both amateur enthusiasts and serious scientists groups were hybridizing species and propagating the new plants from cuttings. In 1760, seed of pelargoniums were sent to John Bertram of Philadelphia, marking the arrival in America, and plants were brought back from France by Thomas Jefferson.
There are more than 200 species of geraniums, only a few of which are widely grown. Within those types, some can be propagated from seed, some only vegetatively from cuttings. Geraniums from seed are primarily available in single flowered form only. Their flowers tend to shatter. This is a drawback for growers but an advantage for you because you don't need to groom the plants, pinching off dead blooms.
Geraniums grown from vegetatively propagated cuttings can have single, semi-double or fully double florets. You can tell if the geranium you bought was cutting grown by noting the type of floret it has (semi-double or double) and by observing whether or not the flower umbel shatters. If the flower does not have a tendency to shatter it probably is a cutting geranium. Gardeners usually remove the dead umbel from the plant for cosmetic reasons but it also helps reduce the risk of fungal diseases. In addition to common or zonal and ivy types, regals (Martha Washingtons) and scented-leaf types are cutting grown geraniums.
Geraniums need full sun to grow and flower well. They won't grow and flower well in shade. This means six or more hours of direct sun daily. Geraniums do best when day temperatures range between the 70's to low 80's and night temperatures in the 60's. Higher temperatures retard growth and flowering. In our area geraniums are best planted in the fall and will perform well until temperatures soar in the late spring. Beyond that requirement, geraniums look great in a variety of gardens: Use them on their own in beds, edging a perennial border, mixed in with other annuals, in patio containers and window boxes - anywhere you want a vibrant touch of color that will last all season
Geraniums grow well in a fairly rich soil that has good drainage. When you have selected a site, dig the soil to loosen it and work in a 1- to 2 inch layer of compost. Add about 1 pound of 10-10-10 fertilizer per 100 square feet. You'll find a variety of growth habits and flower colors at garden centers. Look for healthy compact growth and dark green leaves with no discolored spots above or underneath. Avoid straggly stems that indicate the geraniums were grown in poor light; and obvious pests on stems, leaves or buds. Set geraniums in the ground at the same depth or slightly below the level they were growing in the pots. Space the plants about 8 to 12 inches apart, far enough apart to allow good air circulation but close enough so that the planting will make a good showing.
Although geraniums are relatively care-free, they do need some attention. They're heavy feeders, so you should fertilize them every two weeks or at least once a month. Use a balanced, water-soluble fertilizer (look for 10-10-10 or 20-20-20 on the label). Another alternative is to feed them once for the season when you plant them by using a time release fertilizer such as osmocote or nutricote.
Relatively pest free, geraniums can fall prey to a few diseases in the home garden. The most likely to be a problem in the home garden is botrytis. Botrytis is a fungus that tends to show up with heavy morning dews or when days are overcast and rainy. You'll notice it first on the blooms, which will look moldy; eventually they will get brown and mushy. It spreads rapidly from one petal to the next, one plant to the next. The best treatment is removal of the affected blooms and, if necessary, the whole plant. Don't compost the plants; wrap them up and dispose of them in the trash.
Chances are, you may never encounter any pests. Geraniums are one of the easiest, prettiest, and most adaptable flowering plants you can set in your garden. Whether your preference runs to bright reds or subdued pinks, lavender, white or bicolors, you'll find a geranium to match. Good luck and good gardening.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, email - firstname.lastname@example.org or phone 674-4092. You are also visit the Hendry County Extension Office at 225 Pratt Boulevard, LaBelle. Office hours are from 8:30 - 5:00.
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