I am growing these in containers, inside, on a south facing window. What type of soil mix should I purchase?
Any tropical soil mix will do. Add a quarter by volume of sand for the Aloe vera.
Put a humidity tray under the plants since the window sill may be too hot and dry. The patchouli plant should be a bit back of the window. Humidity trays consist of a pan half filled with stones. Add enough water so that the water level is under the top of the stones. Set the plants on the stones, where they will be over water but not in it. Clean it with javex water periodically to get rid of algae.
Do spray both plants with insecticidal soap regularely, since hot and dry conditions allow spider mites and the almost invisible non-net spinning false spidermites to grow at an incredible rate. Patchouli attracts them!