Last but not least is the type of soil mix to use and the fertilizer. Many commercially manufactured soil mixes are balanced in texture and nutrients and are satisfactory for most household plants. We manufacture our our soil mix here on the farm for spring planting in the greenhouse with a combination of peat moss, perlite, various essential nutrients and some other ingredients (a secret family recipe my father-in-law made and has tweaked over time). It's also great for use in the flower beds and we make it available for sale here at the farm. There are some specific mixtures for African Violets and the like and also for cacti. A good potting soil is a mixture of textures, or particle sizes and provides good drainage, holding the necessary amount of water in the soil well and also providing anchorage for the plants' roots. Soil pH for most indoor plants should be close to neutral, about 6.7 - 7.5, although there are some plant species that prefer more acidic soil types. You can check the pH of the soil with litmus test paper from a pharmacy or you can purchase a fancy pH meter with probes specifically for soil testing. Typically, many manufactured potting mixes are of a balanced pH and will tell you on the bag what types of plants they are suitable for. You can get special types of mixes based on the type of plants you are working with as well. Check your local garden center for a good selection and knowlegeable sales people. As for fertilizers, it all depends on the types of plants you have. There are many fertilizers suitable for a broad range of everyday plants. There are also specific fertilizers for vegetable plants, certain houseplants, roses, hydrangeas, etc. Check the label carefully and be sure what you are purchasing is the proper fertilizer for your plants. There are organic fertilizers also and they encompass many different needs as well. There again, we mix our own fertilizers based upon the crop schedule and growth needs of plants from start to finish. Typically, you will see N-P-K, the three main elements in a fertilizer. They stand for Nitrogen, Phosphorous and Potassium, respectively. Nitrogen affects the rate of vegetative growth of the plant, Phosphorous increases the amount of flowering and root growth, and Potassium is needed for fruit quality and the resistance to disease. If you'd like more in-depth information, there is a great article from the agriculture department of the state of North Carolina; just click on this post's title.