Scented pelargoniums grow best in slightly acidic soil with a pH of 6 to 6.5. Clay pots look aesthetically pleasing, but the soil will dry out faster than if they were in plastic pots. Water the plants when the topsoil feels dry, and the water runs out of the drainage hole.  

During the growing season, February through October, apply a water-soluble fertilizer 10-10-10, half the amount the manufacturers recommend every other watering.

November through January, use the same fertilizer once every eight waterings. Scented Pelargoniums grow best at temperatures of 50 to 60 F at night and 65 to 75 during the day.

During the summer I have my potted plants on the south side of the house sitting on a potting bench backed up against a fence. The plants are shaded for more than half the day because temperatures can reach over 100 degrees. When extremely hot they need to be watered daily.

Bring your scented pelargoniums inside before the temperature reaches 45 degrees. The ideal place for them indoors would be a south-facing window with at least 4 hours of direct sunlight. In frost-free areas, they can be left outside during the winter. 

For more information about these aromatic-leafed plants the book Scented Geraniums, by Jim Becker, is a informative read.