How to Care for a Saguaro Cactus

Keep your saguaro in hot to moderate temperatures year-round. Don't let the winter temperatures get below 45 degrees Fahrenheit. If you live in a temperate climate, keep your saguaro indoors for the winter. If you live in an arid climate, like that of Arizona or California, your plant will be fine outdoors for the winter. These cactus plants need full sun.

Water saguaro once a month during its growing season, in the spring and summer. When these plants go dormant for winter, they don't need any water at all. You can tell your cactus needs water by pressing on its flesh with your finger. If it is firm to the touch, it does not need water.

Fertilize indoor saguaro with a 5-10-10 fertilizer every two to three months during the spring and summer. Apply the recommended amount based on the size of your plant. Saguaros outside may not need fertilizer; the Arizona Cooperative Extension cautions against applying it since the plants have adapted to local soils.

Look out for holes along the trunk. These can indicate bacterial infections and rot, which can eventually kill the cactus. If you see holes, cut them out using a sharp knife. Apply sulfur over the area to treat underlying problems of necrosis or bacteria. If left untreated, the cactus will die.