If you are lucky enough to have a cactus plant, you have one of the easiest plants to take care of. Cactus plants raised in pots need only three things: sun, food and water. Of the three, sun is the most important. Cactus plants, because they are desert plants, need only small amounts of water and the food they need can come from the soil or from a fertilizer applied occasionally throughout the year.
Transplant your cactus plant immediately upon bringing it home. The small container the plant was sold in may be devoid of soil nutrients needed to keep the plant healthy.
Water the cactus until the soil is moist throughout after repotting. Insert a pencil into the soil and if it is damp after removing it from the soil, the cactus has enough water.
Place the cactus in a sunny location. This can be a sunny window of your home. If placing the cactus on a patio, start it out in a partially shaded area until it gets used to bright sunlight. Cactus can burn from over-exposure to full sun.
Fertilize the cactus three times during the year. Cactus plants do the majority of their growing during the spring, summer and fall, so fertilize during these seasons.
Water the plant only when the soil becomes dry. For a house cactus, this may be only once a month. For outdoor cactus plants, you may need to water twice weekly. Use the pencil method to determine when water is needed. If the pencil comes out of the soil dry, it is time to water.