How to Care for a Barrel Cactus

Wash a heavy clay container with soapy water and rinse it in one part bleach mixed with nine parts water. Clay plant pots are best for plants that need arid conditions like cacti and succulents. The porous sides of the container allow moisture to wick away from the root ball after watering.

Drill four drainage holes with an electric drill in the bottom of the container if they are absent. Cover the bottom of the plant pot with a wire mesh and fill with a soil mixture of equal parts of peat moss, potting soil and sand. Plant the cactus at the same level that it was growing. Do not water for three to five days.

Place the barrel cactus in an area with bright sunlight, which is usually a south- or west-facing window. This cactus requires several hours of sunshine per day. Supplement the light with fluorescent bulbs hung 6 inches above the top of the plant if there isn't enough natural sunlight.

Water the cactus regularly from March until the end of September. Let the soil dry a little bit between waterings. During the dormant period in the winter, give the plant 1 cup of water every two weeks. This variety of cactus dies if allowed to stand in water, so remove the excess water from the drip tray at the bottom of the container.

Feed the barrel cactus with water-soluble 5-10-5 fertilizer once a month from June until September. Do not fertilize this plant during the winter when it is not growing.