How often should I fertilize cacti and succulents?

Most cacti and succulents don't actually need much fertilizer, because they come from dry regions and can get by with few nutrients. During the growth phase (spring and summer), you can water them every two to four weeks with diluted fertilizer, and in the cold season you don't need to fertilize at all. A specialized cactus fertilizer with low nitrogen concentration is better than regular all-purpose fertilizer, otherwise the plants grow too quickly and too soft and become more prone to rot.