The geranium is a flowering plant that is native to South Africa. As of 2010, there are more than 100 varieties of geranium, ranging in color from white to pink to red. Red geraniums are known as "common geraniums." Red common geraniums grow well indoors and outdoors and require specific care in order to keep them healthy and blooming.
Geraniums prefer soil that is well-drained. Rich, heavy soil or soil that is clay-like is not conducive to growing geraniums. Rich and clay soils are amended with sand, peat or perlite to make the soil's drain rate more satisfactory for geraniums.
Geraniums require watering at least once a week, if there has not been any rainfall during the week. Because their foliage is susceptible to fungal infection, mulching the base of the plant is suggested, to prevent splash-back with watering.
Geraniums are heavy eaters, and fertilizer provides the extra nutrients they need to produce new growth and flowers. A 20-20-20 water-soluble fertilizer is ideal for the common geranium. Geraniums crave fertilizer during their spring and summer growing seasons. Fertilization during the fall and winter months results in burned roots and foliage.
Bright, direct sunlight is ideal for common geraniums. Geraniums grow best along the sunniest side of the house. The plants will grow in filtered light and shade, but their growth is affected. Geraniums that receive too much shade during the day produce fewer flowers than those that get at least eight hours of full sunshine each day.
Geraniums are propagated from stem cuttings. Propagation is best done during the fall months of September or October. Geranium stem cuttings root well in sand, moist soil or filtered water alone. Cuttings must remain indoors throughout the winter and early spring, until the last threat of frost has passed.