Each container must have good drainage. The potting medium should be well-drained and high in organic matter. A good mixture might contain equal parts of garden loam, peat moss and coarse sand or perlite. Professionally prepared commercial soil mixes may also be satisfactory. You may have to try several before you find one that gives good results for your particular growing conditions.
Geraniums respond favorably to having the soil dry out somewhat between each watering.
Apply enough water so that some drains from the bottom of the container each time you water. Water only as needed, checking the soil for dryness to a depth of 4 to 6 inches. Fertilize semi-monthly from March through October. If plants are being grown where light intensity is low or indoors during the winter months, reduce the amount of fertilizer accordingly. Apply fertilizer according to directions on the label, and make sure that the soil is moist before applying.