Geraniums can be grown as a perennial in warmer climates, but must be grown as a house plant or annual in the north. Geraniums will give constant blooms all season long, and those who want to take a little bit of extra effort can save the plants and have them grow again, even in cold areas.
Basically there are three types of geraniums: zonal, ivy and regal, also known as Lady Washington. Zonal geraniums are the most popular and the ones most commonly used in flower beds and pots. Ivy geraniums are more suited for hanging baskets and window boxes, and regal are not for planting outdoors. They are best as an indoor plant because they need cold temperatures at night.
Zonal geraniums can grow to as tall as 2 feet, and, if you pinch back the flowers, they can grow just as wide. Ivy geraniums can grow as long as 2 feet, and regal can grow 2 1/2 feet tall. The leaves will be a deep green in color with scalloped or ruffled edges, 3 to 5 inches wide, and with a fuzzy or smooth feel. The leaves of zonal geraniums will have red or yellow horseshoe-shaped markings. Some varieties will have a cream-colored marking in the shape of a heart on the leaf, and others will have variegated leaves of green and white. The ivy geranium has leaves that are similar to regular ivy plants, smooth and shiny, and the regal has leaves that are rough and pointed with jagged edges. The flowers are small florets that grow in clusters that measure 2 to 3 inches around. The colors can be red, rose, pink, salmon or white, and some can be bi-colored. Regals can also come in
orange, mauve or purple, and sometimes in a blend of two or three colors.
There are ways to get a geranium to winter over in cold climates. The first method is to dig up the geranium and put it in a pot. Cut it back by about one-third, give it a good soaking with water, and put it in a spot indoors where it is cool but well lit. If necessary, use a plant light and keep it on all of the time. You can also make a geranium go dormant for the winter. Dig the plant up in the fall and just leave a little loose dirt on the roots. Hang the plant upside down someplace where the temperature will stay in the neighborhood of 50 Fahrenheit. Once a month you will need to take the geranium down and soak the roots in water for an hour, then hang it back up again. The leaves will die, but the stem will live. In the spring, simple re-plant it.
Fall is the time to think about making new plants for next year. Take cuttings, about 3 to 4 inches long, from the green, soft part of the stem. Remove all the leaves on the bottom half of the cutting. Dip the cut end into rooting hormone, and then put that end into a pot filled with vermiculite, making sure there is good drainage. The cutting will need a lot of humidity, so put the pot in a plastic bag. It will take from six weeks to two months to take root. Then keep the cuttings in a sunny,but cool place until all danger of frost is gone and they can go back outside again.
Geraniums can fall prey to several insects, namely caterpillars, aphids, whiteflies, mites and slugs. There are sprays that can control most of them, and there are special slug traps.