How to Grow Silver Torch Cactus

Prepare a special potting soil for your cactus. Mix equal parts of coarse builders sand and commercial indoor potting soil.

Repot silver torch cactus only when it outgrows its current pot. Transplant when the root system reaches within 1/4 inch of the edge of the pot. Select a new pot that is just 1 inch larger than the current container.

Place silver torch cactus in full sun in a south- or west-facing window. During the winter, especially in northern latitudes, leave the curtains or blinds open all day so the cactus sits unobstructed in front of the glass. Ideally, provide 12 to 18 hours of bright light a day, using fluorescent grow lights if needed. Position the lights within 12 to 18 inches of the top of the cactus for best results.

Water using warm or room temperatures water, only when the soil feels dry at least 2 inches below the surface and the pot feels noticeably lighter. Overwatering cactus is almost always fatal. During the slow-growing period in winter, it may only be necessary to water your cactus every two to three weeks.

Keep your silver torch cactus in temperatures between 65 and 90 degrees Fahrenheit during the growing season, from spring to fall. Move them outdoors after all danger of frost has passed. They grow well in full sun outdoors, but must first be put in the shade until they adjust to the brighter light outdoors. During winter, keep your silver torch cactus at temperatures between 45 and 55 F, if possible. While not absolutely necessary, maintaining this cactus at a lower temperature during its dormant season encourages it to develop flower buds, according to the University of Nebraska Extension website.

Fertilize every two to three months during the growing season. Use a low nitrogen granulated fertilizer, such as 5-10-10. Sprinkle it on the surface of the soil, following the manufacturer's recommendations. Do not fertilize during the plant's winter dormancy period.

Inspect the silver torch cactus occasionally for aphids, red spider mites, gnats, scale and mealy bugs. These pests are easily controlled on cactus through the use of a commercial insecticide or horticultural oil, following the manufacturer's label directions as to application rates and methods.